Java tutorial
/* * Copyright (c) 2003, 2019, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package javax.sql.rowset; import java.sql.*; import javax.sql.*; import javax.naming.*; import java.io.*; import java.math.*; import java.util.*; import javax.sql.rowset.spi.*; /** * The interface that all standard implementations of * <code>CachedRowSet</code> must implement. * <P> * The reference implementation of the <code>CachedRowSet</code> interface provided * by Oracle Corporation is a standard implementation. Developers may use this implementation * just as it is, they may extend it, or they may choose to write their own implementations * of this interface. * <P> * A <code>CachedRowSet</code> object is a container for rows of data * that caches its rows in memory, which makes it possible to operate without always being * connected to its data source. Further, it is a * JavaBeans™ component and is scrollable, * updatable, and serializable. A <code>CachedRowSet</code> object typically * contains rows from a result set, but it can also contain rows from any file * with a tabular format, such as a spread sheet. The reference implementation * supports getting data only from a <code>ResultSet</code> object, but * developers can extend the <code>SyncProvider</code> implementations to provide * access to other tabular data sources. * <P> * An application can modify the data in a <code>CachedRowSet</code> object, and * those modifications can then be propagated back to the source of the data. * <P> * A <code>CachedRowSet</code> object is a <i>disconnected</i> rowset, which means * that it makes use of a connection to its data source only briefly. It connects to its * data source while it is reading data to populate itself with rows and again * while it is propagating changes back to its underlying data source. The rest * of the time, a <code>CachedRowSet</code> object is disconnected, including * while its data is being modified. Being disconnected makes a <code>RowSet</code> * object much leaner and therefore much easier to pass to another component. For * example, a disconnected <code>RowSet</code> object can be serialized and passed * over the wire to a thin client such as a personal digital assistant (PDA). * * * <h2>1.0 Creating a <code>CachedRowSet</code> Object</h2> * The following line of code uses the default constructor for * <code>CachedRowSet</code> * supplied in the reference implementation (RI) to create a default * <code>CachedRowSet</code> object. * <PRE> * CachedRowSetImpl crs = new CachedRowSetImpl(); * </PRE> * This new <code>CachedRowSet</code> object will have its properties set to the * default properties of a <code>BaseRowSet</code> object, and, in addition, it will * have an <code>RIOptimisticProvider</code> object as its synchronization provider. * <code>RIOptimisticProvider</code>, one of two <code>SyncProvider</code> * implementations included in the RI, is the default provider that the * <code>SyncFactory</code> singleton will supply when no synchronization * provider is specified. * <P> * A <code>SyncProvider</code> object provides a <code>CachedRowSet</code> object * with a reader (a <code>RowSetReader</code> object) for reading data from a * data source to populate itself with data. A reader can be implemented to read * data from a <code>ResultSet</code> object or from a file with a tabular format. * A <code>SyncProvider</code> object also provides * a writer (a <code>RowSetWriter</code> object) for synchronizing any * modifications to the <code>CachedRowSet</code> object's data made while it was * disconnected with the data in the underlying data source. * <P> * A writer can be implemented to exercise various degrees of care in checking * for conflicts and in avoiding them. * (A conflict occurs when a value in the data source has been changed after * the rowset populated itself with that value.) * The <code>RIOptimisticProvider</code> implementation assumes there will be * few or no conflicts and therefore sets no locks. It updates the data source * with values from the <code>CachedRowSet</code> object only if there are no * conflicts. * Other writers can be implemented so that they always write modified data to * the data source, which can be accomplished either by not checking for conflicts * or, on the other end of the spectrum, by setting locks sufficient to prevent data * in the data source from being changed. Still other writer implementations can be * somewhere in between. * <P> * A <code>CachedRowSet</code> object may use any * <code>SyncProvider</code> implementation that has been registered * with the <code>SyncFactory</code> singleton. An application * can find out which <code>SyncProvider</code> implementations have been * registered by calling the following line of code. * <PRE> * java.util.Enumeration providers = SyncFactory.getRegisteredProviders(); * </PRE> * <P> * There are two ways for a <code>CachedRowSet</code> object to specify which * <code>SyncProvider</code> object it will use. * <UL> * <LI>Supplying the name of the implementation to the constructor<BR> * The following line of code creates the <code>CachedRowSet</code> * object <i>crs2</i> that is initialized with default values except that its * <code>SyncProvider</code> object is the one specified. * <PRE> * CachedRowSetImpl crs2 = new CachedRowSetImpl( * "com.fred.providers.HighAvailabilityProvider"); * </PRE> * <LI>Setting the <code>SyncProvider</code> using the <code>CachedRowSet</code> * method <code>setSyncProvider</code><BR> * The following line of code resets the <code>SyncProvider</code> object * for <i>crs</i>, the <code>CachedRowSet</code> object created with the * default constructor. * <PRE> * crs.setSyncProvider("com.fred.providers.HighAvailabilityProvider"); * </PRE> * </UL> * See the comments for <code>SyncFactory</code> and <code>SyncProvider</code> for * more details. * * * <h2>2.0 Retrieving Data from a <code>CachedRowSet</code> Object</h2> * Data is retrieved from a <code>CachedRowSet</code> object by using the * getter methods inherited from the <code>ResultSet</code> * interface. The following examples, in which <code>crs</code> is a * <code>CachedRowSet</code> * object, demonstrate how to iterate through the rows, retrieving the column * values in each row. The first example uses the version of the * getter methods that take a column number; the second example * uses the version that takes a column name. Column numbers are generally * used when the <code>RowSet</code> object's command * is of the form <code>SELECT * FROM TABLENAME</code>; column names are most * commonly used when the command specifies columns by name. * <PRE> * while (crs.next()) { * String name = crs.getString(1); * int id = crs.getInt(2); * Clob comment = crs.getClob(3); * short dept = crs.getShort(4); * System.out.println(name + " " + id + " " + comment + " " + dept); * } * </PRE> * * <PRE> * while (crs.next()) { * String name = crs.getString("NAME"); * int id = crs.getInt("ID"); * Clob comment = crs.getClob("COM"); * short dept = crs.getShort("DEPT"); * System.out.println(name + " " + id + " " + comment + " " + dept); * } * </PRE> * <h3>2.1 Retrieving <code>RowSetMetaData</code></h3> * An application can get information about the columns in a <code>CachedRowSet</code> * object by calling <code>ResultSetMetaData</code> and <code>RowSetMetaData</code> * methods on a <code>RowSetMetaData</code> object. The following code fragment, * in which <i>crs</i> is a <code>CachedRowSet</code> object, illustrates the process. * The first line creates a <code>RowSetMetaData</code> object with information * about the columns in <i>crs</i>. The method <code>getMetaData</code>, * inherited from the <code>ResultSet</code> interface, returns a * <code>ResultSetMetaData</code> object, which is cast to a * <code>RowSetMetaData</code> object before being assigned to the variable * <i>rsmd</i>. The second line finds out how many columns <i>jrs</i> has, and * the third line gets the JDBC type of values stored in the second column of * <code>jrs</code>. * <PRE> * RowSetMetaData rsmd = (RowSetMetaData)crs.getMetaData(); * int count = rsmd.getColumnCount(); * int type = rsmd.getColumnType(2); * </PRE> * The <code>RowSetMetaData</code> interface differs from the * <code>ResultSetMetaData</code> interface in two ways. * <UL> * <LI><i>It includes <code>setter</code> methods:</i> A <code>RowSet</code> * object uses these methods internally when it is populated with data from a * different <code>ResultSet</code> object. * * <LI><i>It contains fewer <code>getter</code> methods:</i> Some * <code>ResultSetMetaData</code> methods to not apply to a <code>RowSet</code> * object. For example, methods retrieving whether a column value is writable * or read only do not apply because all of a <code>RowSet</code> object's * columns will be writable or read only, depending on whether the rowset is * updatable or not. * </UL> * NOTE: In order to return a <code>RowSetMetaData</code> object, implementations must * override the <code>getMetaData()</code> method defined in * <code>java.sql.ResultSet</code> and return a <code>RowSetMetaData</code> object. * * <h2>3.0 Updating a <code>CachedRowSet</code> Object</h2> * Updating a <code>CachedRowSet</code> object is similar to updating a * <code>ResultSet</code> object, but because the rowset is not connected to * its data source while it is being updated, it must take an additional step * to effect changes in its underlying data source. After calling the method * <code>updateRow</code> or <code>insertRow</code>, a * <code>CachedRowSet</code> * object must also call the method <code>acceptChanges</code> to have updates * written to the data source. The following example, in which the cursor is * on a row in the <code>CachedRowSet</code> object <i>crs</i>, shows * the code required to update two column values in the current row and also * update the <code>RowSet</code> object's underlying data source. * <PRE> * crs.updateShort(3, 58); * crs.updateInt(4, 150000); * crs.updateRow(); * crs.acceptChanges(); * </PRE> * <P> * The next example demonstrates moving to the insert row, building a new * row on the insert row, inserting it into the rowset, and then calling the * method <code>acceptChanges</code> to add the new row to the underlying data * source. Note that as with the getter methods, the updater methods may take * either a column index or a column name to designate the column being acted upon. * <PRE> * crs.moveToInsertRow(); * crs.updateString("Name", "Shakespeare"); * crs.updateInt("ID", 10098347); * crs.updateShort("Age", 58); * crs.updateInt("Sal", 150000); * crs.insertRow(); * crs.moveToCurrentRow(); * crs.acceptChanges(); * </PRE> * <P> * NOTE: Where the <code>insertRow()</code> method inserts the contents of a * <code>CachedRowSet</code> object's insert row is implementation-defined. * The reference implementation for the <code>CachedRowSet</code> interface * inserts a new row immediately following the current row, but it could be * implemented to insert new rows in any number of other places. * <P> * Another thing to note about these examples is how they use the method * <code>acceptChanges</code>. It is this method that propagates changes in * a <code>CachedRowSet</code> object back to the underlying data source, * calling on the <code>RowSet</code> object's writer internally to write * changes to the data source. To do this, the writer has to incur the expense * of establishing a connection with that data source. The * preceding two code fragments call the method <code>acceptChanges</code> * immediately after calling <code>updateRow</code> or <code>insertRow</code>. * However, when there are multiple rows being changed, it is more efficient to call * <code>acceptChanges</code> after all calls to <code>updateRow</code> * and <code>insertRow</code> have been made. If <code>acceptChanges</code> * is called only once, only one connection needs to be established. * * <h2>4.0 Updating the Underlying Data Source</h2> * When the method <code>acceptChanges</code> is executed, the * <code>CachedRowSet</code> object's writer, a <code>RowSetWriterImpl</code> * object, is called behind the scenes to write the changes made to the * rowset to the underlying data source. The writer is implemented to make a * connection to the data source and write updates to it. * <P> * A writer is made available through an implementation of the * <code>SyncProvider</code> interface, as discussed in section 1, * "Creating a <code>CachedRowSet</code> Object." * The default reference implementation provider, <code>RIOptimisticProvider</code>, * has its writer implemented to use an optimistic concurrency control * mechanism. That is, it maintains no locks in the underlying database while * the rowset is disconnected from the database and simply checks to see if there * are any conflicts before writing data to the data source. If there are any * conflicts, it does not write anything to the data source. * <P> * The reader/writer facility * provided by the <code>SyncProvider</code> class is pluggable, allowing for the * customization of data retrieval and updating. If a different concurrency * control mechanism is desired, a different implementation of * <code>SyncProvider</code> can be plugged in using the method * <code>setSyncProvider</code>. * <P> * In order to use the optimistic concurrency control routine, the * <code>RIOptimisticProvider</code> maintains both its current * value and its original value (the value it had immediately preceding the * current value). Note that if no changes have been made to the data in a * <code>RowSet</code> object, its current values and its original values are the same, * both being the values with which the <code>RowSet</code> object was initially * populated. However, once any values in the <code>RowSet</code> object have been * changed, the current values and the original values will be different, though at * this stage, the original values are still the initial values. With any subsequent * changes to data in a <code>RowSet</code> object, its original values and current * values will still differ, but its original values will be the values that * were previously the current values. * <P> * Keeping track of original values allows the writer to compare the <code>RowSet</code> * object's original value with the value in the database. If the values in * the database differ from the <code>RowSet</code> object's original values, which means that * the values in the database have been changed, there is a conflict. * Whether a writer checks for conflicts, what degree of checking it does, and how * it handles conflicts all depend on how it is implemented. * * <h2>5.0 Registering and Notifying Listeners</h2> * Being JavaBeans components, all rowsets participate in the JavaBeans event * model, inheriting methods for registering listeners and notifying them of * changes from the <code>BaseRowSet</code> class. A listener for a * <code>CachedRowSet</code> object is a component that wants to be notified * whenever there is a change in the rowset. For example, if a * <code>CachedRowSet</code> object contains the results of a query and * those * results are being displayed in, say, a table and a bar graph, the table and * bar graph could be registered as listeners with the rowset so that they can * update themselves to reflect changes. To become listeners, the table and * bar graph classes must implement the <code>RowSetListener</code> interface. * Then they can be added to the <Code>CachedRowSet</code> object's list of * listeners, as is illustrated in the following lines of code. * <PRE> * crs.addRowSetListener(table); * crs.addRowSetListener(barGraph); * </PRE> * Each <code>CachedRowSet</code> method that moves the cursor or changes * data also notifies registered listeners of the changes, so * <code>table</code> and <code>barGraph</code> will be notified when there is * a change in <code>crs</code>. * * <h2>6.0 Passing Data to Thin Clients</h2> * One of the main reasons to use a <code>CachedRowSet</code> object is to * pass data between different components of an application. Because it is * serializable, a <code>CachedRowSet</code> object can be used, for example, * to send the result of a query executed by an enterprise JavaBeans component * running in a server environment over a network to a client running in a * web browser. * <P> * While a <code>CachedRowSet</code> object is disconnected, it can be much * leaner than a <code>ResultSet</code> object with the same data. * As a result, it can be especially suitable for sending data to a thin client * such as a PDA, where it would be inappropriate to use a JDBC driver * due to resource limitations or security considerations. * Thus, a <code>CachedRowSet</code> object provides a means to "get rows in" * without the need to implement the full JDBC API. * * <h2>7.0 Scrolling and Updating</h2> * A second major use for <code>CachedRowSet</code> objects is to provide * scrolling and updating for <code>ResultSet</code> objects that * do not provide these capabilities themselves. In other words, a * <code>CachedRowSet</code> object can be used to augment the * capabilities of a JDBC technology-enabled driver (hereafter called a * "JDBC driver") when the DBMS does not provide full support for scrolling and * updating. To achieve the effect of making a non-scrollable and read-only * <code>ResultSet</code> object scrollable and updatable, a programmer * simply needs to create a <code>CachedRowSet</code> object populated * with that <code>ResultSet</code> object's data. This is demonstrated * in the following code fragment, where <code>stmt</code> is a * <code>Statement</code> object. * <PRE> * ResultSet rs = stmt.executeQuery("SELECT * FROM EMPLOYEES"); * CachedRowSetImpl crs = new CachedRowSetImpl(); * crs.populate(rs); * </PRE> * <P> * The object <code>crs</code> now contains the data from the table * <code>EMPLOYEES</code>, just as the object <code>rs</code> does. * The difference is that the cursor for <code>crs</code> can be moved * forward, backward, or to a particular row even if the cursor for * <code>rs</code> can move only forward. In addition, <code>crs</code> is * updatable even if <code>rs</code> is not because by default, a * <code>CachedRowSet</code> object is both scrollable and updatable. * <P> * In summary, a <code>CachedRowSet</code> object can be thought of as simply * a disconnected set of rows that are being cached outside of a data source. * Being thin and serializable, it can easily be sent across a wire, * and it is well suited to sending data to a thin client. However, a * <code>CachedRowSet</code> object does have a limitation: It is limited in * size by the amount of data it can store in memory at one time. * * <h2>8.0 Getting Universal Data Access</h2> * Another advantage of the <code>CachedRowSet</code> class is that it makes it * possible to retrieve and store data from sources other than a relational * database. The reader for a rowset can be implemented to read and populate * its rowset with data from any tabular data source, including a spreadsheet * or flat file. * Because both a <code>CachedRowSet</code> object and its metadata can be * created from scratch, a component that acts as a factory for rowsets * can use this capability to create a rowset containing data from * non-SQL data sources. Nevertheless, it is expected that most of the time, * <code>CachedRowSet</code> objects will contain data that was fetched * from an SQL database using the JDBC API. * * <h2>9.0 Setting Properties</h2> * All rowsets maintain a set of properties, which will usually be set using * a tool. The number and kinds of properties a rowset has will vary, * depending on what the rowset does and how it gets its data. For example, * rowsets that get their data from a <code>ResultSet</code> object need to * set the properties that are required for making a database connection. * If a rowset uses the <code>DriverManager</code> facility to make a * connection, it needs to set a property for the JDBC URL that identifies * the appropriate driver, and it needs to set the properties that give the * user name and password. * If, on the other hand, the rowset uses a <code>DataSource</code> object * to make the connection, which is the preferred method, it does not need to * set the property for the JDBC URL. Instead, it needs to set * properties for the logical name of the data source, for the user name, * and for the password. * <P> * NOTE: In order to use a <code>DataSource</code> object for making a * connection, the <code>DataSource</code> object must have been registered * with a naming service that uses the Java Naming and Directory * Interface™ (JNDI) API. This registration * is usually done by a person acting in the capacity of a system * administrator. * <P> * In order to be able to populate itself with data from a database, a rowset * needs to set a command property. This property is a query that is a * <code>PreparedStatement</code> object, which allows the query to have * parameter placeholders that are set at run time, as opposed to design time. * To set these placeholder parameters with values, a rowset provides * setter methods for setting values of each data type, * similar to the setter methods provided by the <code>PreparedStatement</code> * interface. * <P> * The following code fragment illustrates how the <code>CachedRowSet</code> * object <code>crs</code> might have its command property set. Note that if a * tool is used to set properties, this is the code that the tool would use. * <PRE>{@code * crs.setCommand("SELECT FIRST_NAME, LAST_NAME, ADDRESS FROM CUSTOMERS " + * "WHERE CREDIT_LIMIT > ? AND REGION = ?"); * } </PRE> * <P> * The values that will be used to set the command's placeholder parameters are * contained in the <code>RowSet</code> object's <code>params</code> field, which is a * <code>Vector</code> object. * The <code>CachedRowSet</code> class provides a set of setter * methods for setting the elements in its <code>params</code> field. The * following code fragment demonstrates setting the two parameters in the * query from the previous example. * <PRE> * crs.setInt(1, 5000); * crs.setString(2, "West"); * </PRE> * <P> * The <code>params</code> field now contains two elements, each of which is * an array two elements long. The first element is the parameter number; * the second is the value to be set. * In this case, the first element of <code>params</code> is * <code>1</code>, <code>5000</code>, and the second element is <code>2</code>, * <code>"West"</code>. When an application calls the method * <code>execute</code>, it will in turn call on this <code>RowSet</code> object's reader, * which will in turn invoke its <code>readData</code> method. As part of * its implementation, <code>readData</code> will get the values in * <code>params</code> and use them to set the command's placeholder * parameters. * The following code fragment gives an idea of how the reader * does this, after obtaining the <code>Connection</code> object * <code>con</code>. * <PRE>{@code * PreparedStatement pstmt = con.prepareStatement(crs.getCommand()); * reader.decodeParams(); * // decodeParams figures out which setter methods to use and does something * // like the following: * // for (i = 0; i < params.length; i++) { * // pstmt.setObject(i + 1, params[i]); * // } * }</PRE> * <P> * At this point, the command for <code>crs</code> is the query {@code "SELECT * FIRST_NAME, LAST_NAME, ADDRESS FROM CUSTOMERS WHERE CREDIT_LIMIT > 5000 * AND REGION = "West"}. After the <code>readData</code> method executes * this command with the following line of code, it will have the data from * <code>rs</code> with which to populate <code>crs</code>. * <PRE>{@code * ResultSet rs = pstmt.executeQuery(); * }</PRE> * <P> * The preceding code fragments give an idea of what goes on behind the * scenes; they would not appear in an application, which would not invoke * methods like <code>readData</code> and <code>decodeParams</code>. * In contrast, the following code fragment shows what an application might do. * It sets the rowset's command, sets the command's parameters, and executes * the command. Simply by calling the <code>execute</code> method, * <code>crs</code> populates itself with the requested data from the * table <code>CUSTOMERS</code>. * <PRE>{@code * crs.setCommand("SELECT FIRST_NAME, LAST_NAME, ADDRESS FROM CUSTOMERS" + * "WHERE CREDIT_LIMIT > ? AND REGION = ?"); * crs.setInt(1, 5000); * crs.setString(2, "West"); * crs.execute(); * }</PRE> * * <h2>10.0 Paging Data</h2> * Because a <code>CachedRowSet</code> object stores data in memory, * the amount of data that it can contain at any one * time is determined by the amount of memory available. To get around this limitation, * a <code>CachedRowSet</code> object can retrieve data from a <code>ResultSet</code> * object in chunks of data, called <i>pages</i>. To take advantage of this mechanism, * an application sets the number of rows to be included in a page using the method * <code>setPageSize</code>. In other words, if the page size is set to five, a chunk * of five rows of * data will be fetched from the data source at one time. An application can also * optionally set the maximum number of rows that may be fetched at one time. If the * maximum number of rows is set to zero, or no maximum number of rows is set, there is * no limit to the number of rows that may be fetched at a time. * <P> * After properties have been set, * the <code>CachedRowSet</code> object must be populated with data * using either the method <code>populate</code> or the method <code>execute</code>. * The following lines of code demonstrate using the method <code>populate</code>. * Note that this version of the method takes two parameters, a <code>ResultSet</code> * handle and the row in the <code>ResultSet</code> object from which to start * retrieving rows. * <PRE> * CachedRowSet crs = new CachedRowSetImpl(); * crs.setMaxRows(20); * crs.setPageSize(4); * crs.populate(rsHandle, 10); * </PRE> * When this code runs, <i>crs</i> will be populated with four rows from * <i>rsHandle</i> starting with the tenth row. * <P> * The next code fragment shows populating a <code>CachedRowSet</code> object using the * method <code>execute</code>, which may or may not take a <code>Connection</code> * object as a parameter. This code passes <code>execute</code> the <code>Connection</code> * object <i>conHandle</i>. * <P> * Note that there are two differences between the following code * fragment and the previous one. First, the method <code>setMaxRows</code> is not * called, so there is no limit set for the number of rows that <i>crs</i> may contain. * (Remember that <i>crs</i> always has the overriding limit of how much data it can * store in memory.) The second difference is that the you cannot pass the method * <code>execute</code> the number of the row in the <code>ResultSet</code> object * from which to start retrieving rows. This method always starts with the first row. * <PRE> * CachedRowSet crs = new CachedRowSetImpl(); * crs.setPageSize(5); * crs.execute(conHandle); * </PRE> * After this code has run, <i>crs</i> will contain five rows of data from the * <code>ResultSet</code> object produced by the command for <i>crs</i>. The writer * for <i>crs</i> will use <i>conHandle</i> to connect to the data source and * execute the command for <i>crs</i>. An application is then able to operate on the * data in <i>crs</i> in the same way that it would operate on data in any other * <code>CachedRowSet</code> object. * <P> * To access the next page (chunk of data), an application calls the method * <code>nextPage</code>. This method creates a new <code>CachedRowSet</code> object * and fills it with the next page of data. For example, assume that the * <code>CachedRowSet</code> object's command returns a <code>ResultSet</code> object * <i>rs</i> with 1000 rows of data. If the page size has been set to 100, the first * call to the method <code>nextPage</code> will create a <code>CachedRowSet</code> object * containing the first 100 rows of <i>rs</i>. After doing what it needs to do with the * data in these first 100 rows, the application can again call the method * <code>nextPage</code> to create another <code>CachedRowSet</code> object * with the second 100 rows from <i>rs</i>. The data from the first <code>CachedRowSet</code> * object will no longer be in memory because it is replaced with the data from the * second <code>CachedRowSet</code> object. After the tenth call to the method <code>nextPage</code>, * the tenth <code>CachedRowSet</code> object will contain the last 100 rows of data from * <i>rs</i>, which are stored in memory. At any given time, the data from only one * <code>CachedRowSet</code> object is stored in memory. * <P> * The method <code>nextPage</code> returns <code>true</code> as long as the current * page is not the last page of rows and <code>false</code> when there are no more pages. * It can therefore be used in a <code>while</code> loop to retrieve all of the pages, * as is demonstrated in the following lines of code. * <PRE> * CachedRowSet crs = CachedRowSetImpl(); * crs.setPageSize(100); * crs.execute(conHandle); * * while(crs.nextPage()) { * while(crs.next()) { * . . . // operate on chunks (of 100 rows each) in crs, * // row by row * } * } * </PRE> * After this code fragment has been run, the application will have traversed all * 1000 rows, but it will have had no more than 100 rows in memory at a time. * <P> * The <code>CachedRowSet</code> interface also defines the method <code>previousPage</code>. * Just as the method <code>nextPage</code> is analogous to the <code>ResultSet</code> * method <code>next</code>, the method <code>previousPage</code> is analogous to * the <code>ResultSet</code> method <code>previous</code>. Similar to the method * <code>nextPage</code>, <code>previousPage</code> creates a <code>CachedRowSet</code> * object containing the number of rows set as the page size. So, for instance, the * method <code>previousPage</code> could be used in a <code>while</code> loop at * the end of the preceding code fragment to navigate back through the pages from the last * page to the first page. * The method <code>previousPage</code> is also similar to <code>nextPage</code> * in that it can be used in a <code>while</code> * loop, except that it returns <code>true</code> as long as there is another page * preceding it and <code>false</code> when there are no more pages ahead of it. * <P> * By positioning the cursor after the last row for each page, * as is done in the following code fragment, the method <code>previous</code> * navigates from the last row to the first row in each page. * The code could also have left the cursor before the first row on each page and then * used the method <code>next</code> in a <code>while</code> loop to navigate each page * from the first row to the last row. * <P> * The following code fragment assumes a continuation from the previous code fragment, * meaning that the cursor for the tenth <code>CachedRowSet</code> object is on the * last row. The code moves the cursor to after the last row so that the first * call to the method <code>previous</code> will put the cursor back on the last row. * After going through all of the rows in the last page (the <code>CachedRowSet</code> * object <i>crs</i>), the code then enters * the <code>while</code> loop to get to the ninth page, go through the rows backwards, * go to the eighth page, go through the rows backwards, and so on to the first row * of the first page. * * <PRE> * crs.afterLast(); * while(crs.previous()) { * . . . // navigate through the rows, last to first * { * while(crs.previousPage()) { * crs.afterLast(); * while(crs.previous()) { * . . . // go from the last row to the first row of each page * } * } * </PRE> * * @author Jonathan Bruce * @since 1.5 */ public interface CachedRowSet extends RowSet, Joinable { /** * Populates this <code>CachedRowSet</code> object with data from * the given <code>ResultSet</code> object. * <P> * This method can be used as an alternative to the <code>execute</code> method when an * application has a connection to an open <code>ResultSet</code> object. * Using the method <code>populate</code> can be more efficient than using * the version of the <code>execute</code> method that takes no parameters * because it does not open a new connection and re-execute this * <code>CachedRowSet</code> object's command. Using the <code>populate</code> * method is more a matter of convenience when compared to using the version * of <code>execute</code> that takes a <code>ResultSet</code> object. * * @param data the <code>ResultSet</code> object containing the data * to be read into this <code>CachedRowSet</code> object * @throws SQLException if a null <code>ResultSet</code> object is supplied * or this <code>CachedRowSet</code> object cannot * retrieve the associated <code>ResultSetMetaData</code> object * @see #execute * @see java.sql.ResultSet * @see java.sql.ResultSetMetaData */ public void populate(ResultSet data) throws SQLException; /** * Populates this <code>CachedRowSet</code> object with data, using the * given connection to produce the result set from which the data will be read. * This method should close any database connections that it creates to * ensure that this <code>CachedRowSet</code> object is disconnected except when * it is reading data from its data source or writing data to its data source. * <P> * The reader for this <code>CachedRowSet</code> object * will use <i>conn</i> to establish a connection to the data source * so that it can execute the rowset's command and read data from the * the resulting <code>ResultSet</code> object into this * <code>CachedRowSet</code> object. This method also closes <i>conn</i> * after it has populated this <code>CachedRowSet</code> object. * <P> * If this method is called when an implementation has already been * populated, the contents and the metadata are (re)set. Also, if this method is * called before the method <code>acceptChanges</code> has been called * to commit outstanding updates, those updates are lost. * * @param conn a standard JDBC <code>Connection</code> object with valid * properties * @throws SQLException if an invalid <code>Connection</code> object is supplied * or an error occurs in establishing the connection to the * data source * @see #populate * @see java.sql.Connection */ public void execute(Connection conn) throws SQLException; /** * Propagates row update, insert and delete changes made to this * <code>CachedRowSet</code> object to the underlying data source. * <P> * This method calls on this <code>CachedRowSet</code> object's writer * to do the work behind the scenes. * Standard <code>CachedRowSet</code> implementations should use the * <code>SyncFactory</code> singleton * to obtain a <code>SyncProvider</code> instance providing a * <code>RowSetWriter</code> object (writer). The writer will attempt * to propagate changes made in this <code>CachedRowSet</code> object * back to the data source. * <P> * When the method <code>acceptChanges</code> executes successfully, in * addition to writing changes to the data source, it * makes the values in the current row be the values in the original row. * <P> * Depending on the synchronization level of the <code>SyncProvider</code> * implementation being used, the writer will compare the original values * with those in the data source to check for conflicts. When there is a conflict, * the <code>RIOptimisticProvider</code> implementation, for example, throws a * <code>SyncProviderException</code> and does not write anything to the * data source. * <P> * An application may choose to catch the <code>SyncProviderException</code> * object and retrieve the <code>SyncResolver</code> object it contains. * The <code>SyncResolver</code> object lists the conflicts row by row and * sets a lock on the data source to avoid further conflicts while the * current conflicts are being resolved. * Further, for each conflict, it provides methods for examining the conflict * and setting the value that should be persisted in the data source. * After all conflicts have been resolved, an application must call the * <code>acceptChanges</code> method again to write resolved values to the * data source. If all of the values in the data source are already the * values to be persisted, the method <code>acceptChanges</code> does nothing. * <P> * Some provider implementations may use locks to ensure that there are no * conflicts. In such cases, it is guaranteed that the writer will succeed in * writing changes to the data source when the method <code>acceptChanges</code> * is called. This method may be called immediately after the methods * <code>updateRow</code>, <code>insertRow</code>, or <code>deleteRow</code> * have been called, but it is more efficient to call it only once after * all changes have been made so that only one connection needs to be * established. * <P> * Note: The <code>acceptChanges()</code> method will determine if the * <code>COMMIT_ON_ACCEPT_CHANGES</code> is set to true or not. If it is set * to true, all updates in the synchronization are committed to the data * source. Otherwise, the application <b>must</b> explicitly call the * <code>commit()</code> or <code>rollback()</code> methods as appropriate. * * @throws SyncProviderException if the underlying * synchronization provider's writer fails to write the updates * back to the data source * @see #acceptChanges(java.sql.Connection) * @see javax.sql.RowSetWriter * @see javax.sql.rowset.spi.SyncFactory * @see javax.sql.rowset.spi.SyncProvider * @see javax.sql.rowset.spi.SyncProviderException * @see javax.sql.rowset.spi.SyncResolver */ public void acceptChanges() throws SyncProviderException; /** * Propagates all row update, insert and delete changes to the * data source backing this <code>CachedRowSet</code> object * using the specified <code>Connection</code> object to establish a * connection to the data source. * <P> * The other version of the <code>acceptChanges</code> method is not passed * a connection because it uses * the <code>Connection</code> object already defined within the <code>RowSet</code> * object, which is the connection used for populating it initially. * <P> * This form of the method <code>acceptChanges</code> is similar to the * form that takes no arguments; however, unlike the other form, this form * can be used only when the underlying data source is a JDBC data source. * The updated <code>Connection</code> properties must be used by the * <code>SyncProvider</code> to reset the <code>RowSetWriter</code> * configuration to ensure that the contents of the <code>CachedRowSet</code> * object are synchronized correctly. * <P> * When the method <code>acceptChanges</code> executes successfully, in * addition to writing changes to the data source, it * makes the values in the current row be the values in the original row. * <P> * Depending on the synchronization level of the <code>SyncProvider</code> * implementation being used, the writer will compare the original values * with those in the data source to check for conflicts. When there is a conflict, * the <code>RIOptimisticProvider</code> implementation, for example, throws a * <code>SyncProviderException</code> and does not write anything to the * data source. * <P> * An application may choose to catch the <code>SyncProviderException</code> * object and retrieve the <code>SyncResolver</code> object it contains. * The <code>SyncResolver</code> object lists the conflicts row by row and * sets a lock on the data source to avoid further conflicts while the * current conflicts are being resolved. * Further, for each conflict, it provides methods for examining the conflict * and setting the value that should be persisted in the data source. * After all conflicts have been resolved, an application must call the * <code>acceptChanges</code> method again to write resolved values to the * data source. If all of the values in the data source are already the * values to be persisted, the method <code>acceptChanges</code> does nothing. * <P> * Some provider implementations may use locks to ensure that there are no * conflicts. In such cases, it is guaranteed that the writer will succeed in * writing changes to the data source when the method <code>acceptChanges</code> * is called. This method may be called immediately after the methods * <code>updateRow</code>, <code>insertRow</code>, or <code>deleteRow</code> * have been called, but it is more efficient to call it only once after * all changes have been made so that only one connection needs to be * established. * <P> * Note: The <code>acceptChanges()</code> method will determine if the * <code>COMMIT_ON_ACCEPT_CHANGES</code> is set to true or not. If it is set * to true, all updates in the synchronization are committed to the data * source. Otherwise, the application <b>must</b> explicitly call the * <code>commit</code> or <code>rollback</code> methods as appropriate. * * @param con a standard JDBC <code>Connection</code> object * @throws SyncProviderException if the underlying * synchronization provider's writer fails to write the updates * back to the data source * @see #acceptChanges() * @see javax.sql.RowSetWriter * @see javax.sql.rowset.spi.SyncFactory * @see javax.sql.rowset.spi.SyncProvider * @see javax.sql.rowset.spi.SyncProviderException * @see javax.sql.rowset.spi.SyncResolver */ public void acceptChanges(Connection con) throws SyncProviderException; /** * Restores this <code>CachedRowSet</code> object to its original * value, that is, its value before the last set of changes. If there * have been no changes to the rowset or only one set of changes, * the original value is the value with which this <code>CachedRowSet</code> object * was populated; otherwise, the original value is * the value it had immediately before its current value. * <P> * When this method is called, a <code>CachedRowSet</code> implementation * must ensure that all updates, inserts, and deletes to the current * rowset instance are replaced by the previous values. In addition, * the cursor should be * reset to the first row and a <code>rowSetChanged</code> event * should be fired to notify all registered listeners. * * @throws SQLException if an error occurs rolling back the current value of * this <code>CachedRowSet</code> object to its previous value * @see javax.sql.RowSetListener#rowSetChanged */ public void restoreOriginal() throws SQLException; /** * Releases the current contents of this <code>CachedRowSet</code> * object and sends a <code>rowSetChanged</code> event to all * registered listeners. Any outstanding updates are discarded and * the rowset contains no rows after this method is called. There * are no interactions with the underlying data source, and any rowset * content, metadata, and content updates should be non-recoverable. * <P> * This <code>CachedRowSet</code> object should lock until its contents and * associated updates are fully cleared, thus preventing 'dirty' reads by * other components that hold a reference to this <code>RowSet</code> object. * In addition, the contents cannot be released * until all components reading this <code>CachedRowSet</code> object * have completed their reads. This <code>CachedRowSet</code> object * should be returned to normal behavior after firing the * <code>rowSetChanged</code> event. * <P> * The metadata, including JDBC properties and Synchronization SPI * properties, are maintained for future use. It is important that * properties such as the <code>command</code> property be * relevant to the originating data source from which this <code>CachedRowSet</code> * object was originally established. * <P> * This method empties a rowset, as opposed to the <code>close</code> method, * which marks the entire rowset as recoverable to allow the garbage collector * the rowset's Java VM resources. * * @throws SQLException if an error occurs flushing the contents of this * <code>CachedRowSet</code> object * @see javax.sql.RowSetListener#rowSetChanged * @see java.sql.ResultSet#close */ public void release() throws SQLException; /** * Cancels the deletion of the current row and notifies listeners that * a row has changed. After this method is called, the current row is * no longer marked for deletion. This method can be called at any * time during the lifetime of the rowset. * <P> * In addition, multiple cancellations of row deletions can be made * by adjusting the position of the cursor using any of the cursor * position control methods such as: * <ul> * <li><code>CachedRowSet.absolute</code> * <li><code>CachedRowSet.first</code> * <li><code>CachedRowSet.last</code> * </ul> * * @throws SQLException if (1) the current row has not been deleted or * (2) the cursor is on the insert row, before the first row, or * after the last row * @see javax.sql.rowset.CachedRowSet#undoInsert * @see java.sql.ResultSet#cancelRowUpdates */ public void undoDelete() throws SQLException; /** * Immediately removes the current row from this <code>CachedRowSet</code> * object if the row has been inserted, and also notifies listeners that a * row has changed. This method can be called at any time during the * lifetime of a rowset and assuming the current row is within * the exception limitations (see below), it cancels the row insertion * of the current row. * <P> * In addition, multiple cancellations of row insertions can be made * by adjusting the position of the cursor using any of the cursor * position control methods such as: * <ul> * <li><code>CachedRowSet.absolute</code> * <li><code>CachedRowSet.first</code> * <li><code>CachedRowSet.last</code> * </ul> * * @throws SQLException if (1) the current row has not been inserted or (2) * the cursor is before the first row, after the last row, or on the * insert row * @see javax.sql.rowset.CachedRowSet#undoDelete * @see java.sql.ResultSet#cancelRowUpdates */ public void undoInsert() throws SQLException; /** * Immediately reverses the last update operation if the * row has been modified. This method can be * called to reverse updates on all columns until all updates in a row have * been rolled back to their state just prior to the last synchronization * (<code>acceptChanges</code>) or population. This method may also be called * while performing updates to the insert row. * <P> * <code>undoUpdate</code> may be called at any time during the lifetime of a * rowset; however, after a synchronization has occurred, this method has no * effect until further modification to the rowset data has occurred. * * @throws SQLException if the cursor is before the first row or after the last * row in this <code>CachedRowSet</code> object * @see #undoDelete * @see #undoInsert * @see java.sql.ResultSet#cancelRowUpdates */ public void undoUpdate() throws SQLException; /** * Indicates whether the designated column in the current row of this * <code>CachedRowSet</code> object has been updated. * * @param idx an <code>int</code> identifying the column to be checked for updates * @return <code>true</code> if the designated column has been visibly updated; * <code>false</code> otherwise * @throws SQLException if the cursor is on the insert row, before the first row, * or after the last row * @see java.sql.DatabaseMetaData#updatesAreDetected */ public boolean columnUpdated(int idx) throws SQLException; /** * Indicates whether the designated column in the current row of this * <code>CachedRowSet</code> object has been updated. * * @param columnName a <code>String</code> object giving the name of the * column to be checked for updates * @return <code>true</code> if the column has been visibly updated; * <code>false</code> otherwise * @throws SQLException if the cursor is on the insert row, before the first row, * or after the last row * @see java.sql.DatabaseMetaData#updatesAreDetected */ public boolean columnUpdated(String columnName) throws SQLException; /** * Converts this <code>CachedRowSet</code> object to a <code>Collection</code> * object that contains all of this <code>CachedRowSet</code> object's data. * Implementations have some latitude in * how they can represent this <code>Collection</code> object because of the * abstract nature of the <code>Collection</code> framework. * Each row must be fully represented in either a * general purpose <code>Collection</code> implementation or a specialized * <code>Collection</code> implementation, such as a <code>TreeMap</code> * object or a <code>Vector</code> object. * An SQL <code>NULL</code> column value must be represented as a <code>null</code> * in the Java programming language. * <P> * The standard reference implementation for the <code>CachedRowSet</code> * interface uses a <code>TreeMap</code> object for the rowset, with the * values in each row being contained in <code>Vector</code> objects. It is * expected that most implementations will do the same. * <P> * The <code>TreeMap</code> type of collection guarantees that the map will be in * ascending key order, sorted according to the natural order for the * key's class. * Each key references a <code>Vector</code> object that corresponds to one * row of a <code>RowSet</code> object. Therefore, the size of each * <code>Vector</code> object must be exactly equal to the number of * columns in the <code>RowSet</code> object. * The key used by the <code>TreeMap</code> collection is determined by the * implementation, which may choose to leverage a set key that is * available within the internal <code>RowSet</code> tabular structure by * virtue of a key already set either on the <code>RowSet</code> object * itself or on the underlying SQL data. * * @return a <code>Collection</code> object that contains the values in * each row in this <code>CachedRowSet</code> object * @throws SQLException if an error occurs generating the collection * @see #toCollection(int) * @see #toCollection(String) */ public Collection<?> toCollection() throws SQLException; /** * Converts the designated column in this <code>CachedRowSet</code> object * to a <code>Collection</code> object. Implementations have some latitude in * how they can represent this <code>Collection</code> object because of the * abstract nature of the <code>Collection</code> framework. * Each column value should be fully represented in either a * general purpose <code>Collection</code> implementation or a specialized * <code>Collection</code> implementation, such as a <code>Vector</code> object. * An SQL <code>NULL</code> column value must be represented as a <code>null</code> * in the Java programming language. * <P> * The standard reference implementation uses a <code>Vector</code> object * to contain the column values, and it is expected * that most implementations will do the same. If a <code>Vector</code> object * is used, it size must be exactly equal to the number of rows * in this <code>CachedRowSet</code> object. * * @param column an <code>int</code> indicating the column whose values * are to be represented in a <code>Collection</code> object * @return a <code>Collection</code> object that contains the values * stored in the specified column of this <code>CachedRowSet</code> * object * @throws SQLException if an error occurs generating the collection or * an invalid column id is provided * @see #toCollection * @see #toCollection(String) */ public Collection<?> toCollection(int column) throws SQLException; /** * Converts the designated column in this <code>CachedRowSet</code> object * to a <code>Collection</code> object. Implementations have some latitude in * how they can represent this <code>Collection</code> object because of the * abstract nature of the <code>Collection</code> framework. * Each column value should be fully represented in either a * general purpose <code>Collection</code> implementation or a specialized * <code>Collection</code> implementation, such as a <code>Vector</code> object. * An SQL <code>NULL</code> column value must be represented as a <code>null</code> * in the Java programming language. * <P> * The standard reference implementation uses a <code>Vector</code> object * to contain the column values, and it is expected * that most implementations will do the same. If a <code>Vector</code> object * is used, it size must be exactly equal to the number of rows * in this <code>CachedRowSet</code> object. * * @param column a <code>String</code> object giving the name of the * column whose values are to be represented in a collection * @return a <code>Collection</code> object that contains the values * stored in the specified column of this <code>CachedRowSet</code> * object * @throws SQLException if an error occurs generating the collection or * an invalid column id is provided * @see #toCollection * @see #toCollection(int) */ public Collection<?> toCollection(String column) throws SQLException; /** * Retrieves the <code>SyncProvider</code> implementation for this * <code>CachedRowSet</code> object. Internally, this method is used by a rowset * to trigger read or write actions between the rowset * and the data source. For example, a rowset may need to get a handle * on the rowset reader (<code>RowSetReader</code> object) from the * <code>SyncProvider</code> to allow the rowset to be populated. * <pre> * RowSetReader rowsetReader = null; * SyncProvider provider = * SyncFactory.getInstance("javax.sql.rowset.provider.RIOptimisticProvider"); * if (provider instanceof RIOptimisticProvider) { * rowsetReader = provider.getRowSetReader(); * } * </pre> * Assuming <i>rowsetReader</i> is a private, accessible field within * the rowset implementation, when an application calls the <code>execute</code> * method, it in turn calls on the reader's <code>readData</code> method * to populate the <code>RowSet</code> object. *<pre> * rowsetReader.readData((RowSetInternal)this); * </pre> * <P> * In addition, an application can use the <code>SyncProvider</code> object * returned by this method to call methods that return information about the * <code>SyncProvider</code> object, including information about the * vendor, version, provider identification, synchronization grade, and locks * it currently has set. * * @return the <code>SyncProvider</code> object that was set when the rowset * was instantiated, or if none was set, the default provider * @throws SQLException if an error occurs while returning the * <code>SyncProvider</code> object * @see #setSyncProvider */ public SyncProvider getSyncProvider() throws SQLException; /** * Sets the <code>SyncProvider</code> object for this <code>CachedRowSet</code> * object to the one specified. This method * allows the <code>SyncProvider</code> object to be reset. * <P> * A <code>CachedRowSet</code> implementation should always be instantiated * with an available <code>SyncProvider</code> mechanism, but there are * cases where resetting the <code>SyncProvider</code> object is desirable * or necessary. For example, an application might want to use the default * <code>SyncProvider</code> object for a time and then choose to use a provider * that has more recently become available and better fits its needs. * <P> * Resetting the <code>SyncProvider</code> object causes the * <code>RowSet</code> object to request a new <code>SyncProvider</code> implementation * from the <code>SyncFactory</code>. This has the effect of resetting * all previous connections and relationships with the originating * data source and can potentially drastically change the synchronization * behavior of a disconnected rowset. * * @param provider a <code>String</code> object giving the fully qualified class * name of a <code>SyncProvider</code> implementation * @throws SQLException if an error occurs while attempting to reset the * <code>SyncProvider</code> implementation * @see #getSyncProvider */ public void setSyncProvider(String provider) throws SQLException; /** * Returns the number of rows in this <code>CachedRowSet</code> * object. * * @return number of rows in the rowset */ public int size(); /** * Sets the metadata for this <code>CachedRowSet</code> object with * the given <code>RowSetMetaData</code> object. When a * <code>RowSetReader</code> object is reading the contents of a rowset, * it creates a <code>RowSetMetaData</code> object and initializes * it using the methods in the <code>RowSetMetaData</code> implementation. * The reference implementation uses the <code>RowSetMetaDataImpl</code> * class. When the reader has completed reading the rowset contents, * this method is called internally to pass the <code>RowSetMetaData</code> * object to the rowset. * * @param md a <code>RowSetMetaData</code> object containing * metadata about the columns in this <code>CachedRowSet</code> object * @throws SQLException if invalid metadata is supplied to the * rowset */ public void setMetaData(RowSetMetaData md) throws SQLException; /** * Returns a <code>ResultSet</code> object containing the original value of this * <code>CachedRowSet</code> object. * <P> * The cursor for the <code>ResultSet</code> * object should be positioned before the first row. * In addition, the returned <code>ResultSet</code> object should have the following * properties: * <UL> * <LI>ResultSet.TYPE_SCROLL_INSENSITIVE * <LI>ResultSet.CONCUR_UPDATABLE * </UL> * <P> * The original value for a <code>RowSet</code> object is the value it had before * the last synchronization with the underlying data source. If there have been * no synchronizations, the original value will be the value with which the * <code>RowSet</code> object was populated. This method is called internally * when an application calls the method <code>acceptChanges</code> and the * <code>SyncProvider</code> object has been implemented to check for conflicts. * If this is the case, the writer compares the original value with the value * currently in the data source to check for conflicts. * * @return a <code>ResultSet</code> object that contains the original value for * this <code>CachedRowSet</code> object * @throws SQLException if an error occurs producing the * <code>ResultSet</code> object */ public ResultSet getOriginal() throws SQLException; /** * Returns a <code>ResultSet</code> object containing the original value for the * current row only of this <code>CachedRowSet</code> object. * <P> * The cursor for the <code>ResultSet</code> * object should be positioned before the first row. * In addition, the returned <code>ResultSet</code> object should have the following * properties: * <UL> * <LI>ResultSet.TYPE_SCROLL_INSENSITIVE * <LI>ResultSet.CONCUR_UPDATABLE * </UL> * * @return the original result set of the row * @throws SQLException if there is no current row * @see #setOriginalRow */ public ResultSet getOriginalRow() throws SQLException; /** * Sets the current row in this <code>CachedRowSet</code> object as the original * row. * <P> * This method is called internally after the any modified values in the current * row have been synchronized with the data source. The current row must be tagged * as no longer inserted, deleted or updated. * <P> * A call to <code>setOriginalRow</code> is irreversible. * * @throws SQLException if there is no current row or an error is * encountered resetting the contents of the original row * @see #getOriginalRow */ public void setOriginalRow() throws SQLException; /** * Returns an identifier for the object (table) that was used to * create this <code>CachedRowSet</code> object. This name may be set on multiple occasions, * and the specification imposes no limits on how many times this * may occur or whether standard implementations should keep track * of previous table names. * * @return a <code>String</code> object giving the name of the table that is the * source of data for this <code>CachedRowSet</code> object or <code>null</code> * if no name has been set for the table * @throws SQLException if an error is encountered returning the table name * @see javax.sql.RowSetMetaData#getTableName */ public String getTableName() throws SQLException; /** * Sets the identifier for the table from which this <code>CachedRowSet</code> * object was derived to the given table name. The writer uses this name to * determine which table to use when comparing the values in the data source with the * <code>CachedRowSet</code> object's values during a synchronization attempt. * The table identifier also indicates where modified values from this * <code>CachedRowSet</code> object should be written. * <P> * The implementation of this <code>CachedRowSet</code> object may obtain the * the name internally from the <code>RowSetMetaDataImpl</code> object. * * @param tabName a <code>String</code> object identifying the table from which this <code>CachedRowSet</code> object was derived; cannot be <code>null</code> * but may be an empty string * @throws SQLException if an error is encountered naming the table or * <i>tabName</i> is <code>null</code> * @see javax.sql.RowSetMetaData#setTableName * @see javax.sql.RowSetWriter * @see javax.sql.rowset.spi.SyncProvider */ public void setTableName(String tabName) throws SQLException; /** * Returns an array containing one or more column numbers indicating the columns * that form a key that uniquely * identifies a row in this <code>CachedRowSet</code> object. * * @return an array containing the column number or numbers that indicate which columns * constitute a primary key * for a row in this <code>CachedRowSet</code> object. This array should be * empty if no columns are representative of a primary key. * @throws SQLException if this <code>CachedRowSet</code> object is empty * @see #setKeyColumns * @see Joinable#getMatchColumnIndexes * @see Joinable#getMatchColumnNames */ public int[] getKeyColumns() throws SQLException; /** * Sets this <code>CachedRowSet</code> object's <code>keyCols</code> * field with the given array of column numbers, which forms a key * for uniquely identifying a row in this <code>CachedRowSet</code> object. * <p> * If a <code>CachedRowSet</code> object becomes part of a <code>JoinRowSet</code> * object, the keys defined by this method and the resulting constraints are * maintained if the columns designated as key columns also become match * columns. * * @param keys an array of <code>int</code> indicating the columns that form * a primary key for this <code>CachedRowSet</code> object; every * element in the array must be greater than <code>0</code> and * less than or equal to the number of columns in this rowset * @throws SQLException if any of the numbers in the given array * are not valid for this rowset * @see #getKeyColumns * @see Joinable#setMatchColumn(String) * @see Joinable#setMatchColumn(int) */ public void setKeyColumns(int[] keys) throws SQLException; /** * Returns a new <code>RowSet</code> object backed by the same data as * that of this <code>CachedRowSet</code> object. In effect, both * <code>CachedRowSet</code> objects have a cursor over the same data. * As a result, any changes made by a duplicate are visible to the original * and to any other duplicates, just as a change made by the original is visible * to all of its duplicates. If a duplicate calls a method that changes the * underlying data, the method it calls notifies all registered listeners * just as it would when it is called by the original <code>CachedRowSet</code> * object. * <P> * In addition, any <code>RowSet</code> object * created by this method will have the same properties as this * <code>CachedRowSet</code> object. For example, if this <code>CachedRowSet</code> * object is read-only, all of its duplicates will also be read-only. If it is * changed to be updatable, the duplicates also become updatable. * <P> * NOTE: If multiple threads access <code>RowSet</code> objects created from * the <code>createShared()</code> method, the following behavior is specified * to preserve shared data integrity: reads and writes of all * shared <code>RowSet</code> objects should be made serially between each * object and the single underlying tabular structure. * * @return a new shared <code>RowSet</code> object that has the same properties * as this <code>CachedRowSet</code> object and that has a cursor over * the same data * @throws SQLException if an error occurs or cloning is not * supported in the underlying platform * @see javax.sql.RowSetEvent * @see javax.sql.RowSetListener */ public RowSet createShared() throws SQLException; /** * Creates a <code>RowSet</code> object that is a deep copy of the data in * this <code>CachedRowSet</code> object. In contrast to * the <code>RowSet</code> object generated from a <code>createShared</code> * call, updates made to the copy of the original <code>RowSet</code> object * must not be visible to the original <code>RowSet</code> object. Also, any * event listeners that are registered with the original * <code>RowSet</code> must not have scope over the new * <code>RowSet</code> copies. In addition, any constraint restrictions * established must be maintained. * * @return a new <code>RowSet</code> object that is a deep copy * of this <code>CachedRowSet</code> object and is * completely independent of this <code>CachedRowSet</code> object * @throws SQLException if an error occurs in generating the copy of * the of this <code>CachedRowSet</code> object * @see #createShared * @see #createCopySchema * @see #createCopyNoConstraints * @see javax.sql.RowSetEvent * @see javax.sql.RowSetListener */ public CachedRowSet createCopy() throws SQLException; /** * Creates a <code>CachedRowSet</code> object that is an empty copy of this * <code>CachedRowSet</code> object. The copy * must not contain any contents but only represent the table * structure of the original <code>CachedRowSet</code> object. In addition, primary * or foreign key constraints set in the originating <code>CachedRowSet</code> object must * be equally enforced in the new empty <code>CachedRowSet</code> object. * In contrast to * the <code>RowSet</code> object generated from a <code>createShared</code> method * call, updates made to a copy of this <code>CachedRowSet</code> object with the * <code>createCopySchema</code> method must not be visible to it. * <P> * Applications can form a <code>WebRowSet</code> object from the <code>CachedRowSet</code> * object returned by this method in order * to export the <code>RowSet</code> schema definition to XML for future use. * @return An empty copy of this {@code CachedRowSet} object * @throws SQLException if an error occurs in cloning the structure of this * <code>CachedRowSet</code> object * @see #createShared * @see #createCopySchema * @see #createCopyNoConstraints * @see javax.sql.RowSetEvent * @see javax.sql.RowSetListener */ public CachedRowSet createCopySchema() throws SQLException; /** * Creates a <code>CachedRowSet</code> object that is a deep copy of * this <code>CachedRowSet</code> object's data but is independent of it. * In contrast to * the <code>RowSet</code> object generated from a <code>createShared</code> * method call, updates made to a copy of this <code>CachedRowSet</code> object * must not be visible to it. Also, any * event listeners that are registered with this * <code>CachedRowSet</code> object must not have scope over the new * <code>RowSet</code> object. In addition, any constraint restrictions * established for this <code>CachedRowSet</code> object must <b>not</b> be maintained * in the copy. * * @return a new <code>CachedRowSet</code> object that is a deep copy * of this <code>CachedRowSet</code> object and is * completely independent of this <code>CachedRowSet</code> object * @throws SQLException if an error occurs in generating the copy of * the of this <code>CachedRowSet</code> object * @see #createCopy * @see #createShared * @see #createCopySchema * @see javax.sql.RowSetEvent * @see javax.sql.RowSetListener */ public CachedRowSet createCopyNoConstraints() throws SQLException; /** * Retrieves the first warning reported by calls on this <code>RowSet</code> object. * Subsequent warnings on this <code>RowSet</code> object will be chained to the * <code>RowSetWarning</code> object that this method returns. * * The warning chain is automatically cleared each time a new row is read. * This method may not be called on a RowSet object that has been closed; * doing so will cause a <code>SQLException</code> to be thrown. * * @return RowSetWarning the first <code>RowSetWarning</code> * object reported or null if there are none * @throws SQLException if this method is called on a closed RowSet * @see RowSetWarning */ public RowSetWarning getRowSetWarnings() throws SQLException; /** * Retrieves a <code>boolean</code> indicating whether rows marked * for deletion appear in the set of current rows. If <code>true</code> is * returned, deleted rows are visible with the current rows. If * <code>false</code> is returned, rows are not visible with the set of * current rows. The default value is <code>false</code>. * <P> * Standard rowset implementations may choose to restrict this behavior * due to security considerations or to better fit certain deployment * scenarios. This is left as implementation defined and does not * represent standard behavior. * <P> * Note: Allowing deleted rows to remain visible complicates the behavior * of some standard JDBC <code>RowSet</code> Implementations methods. * However, most rowset users can simply ignore this extra detail because * only very specialized applications will likely want to take advantage of * this feature. * * @return <code>true</code> if deleted rows are visible; * <code>false</code> otherwise * @throws SQLException if a rowset implementation is unable to * to determine whether rows marked for deletion are visible * @see #setShowDeleted */ public boolean getShowDeleted() throws SQLException; /** * Sets the property <code>showDeleted</code> to the given * <code>boolean</code> value, which determines whether * rows marked for deletion appear in the set of current rows. * If the value is set to <code>true</code>, deleted rows are immediately * visible with the set of current rows. If the value is set to * <code>false</code>, the deleted rows are set as invisible with the * current set of rows. * <P> * Standard rowset implementations may choose to restrict this behavior * due to security considerations or to better fit certain deployment * scenarios. This is left as implementations defined and does not * represent standard behavior. * * @param b <code>true</code> if deleted rows should be shown; * <code>false</code> otherwise * @exception SQLException if a rowset implementation is unable to * to reset whether deleted rows should be visible * @see #getShowDeleted */ public void setShowDeleted(boolean b) throws SQLException; /** * Each <code>CachedRowSet</code> object's <code>SyncProvider</code> contains * a <code>Connection</code> object from the <code>ResultSet</code> or JDBC * properties passed to it's constructors. This method wraps the * <code>Connection</code> commit method to allow flexible * auto commit or non auto commit transactional control support. * <p> * Makes all changes that are performed by the <code>acceptChanges()</code> * method since the previous commit/rollback permanent. This method should * be used only when auto-commit mode has been disabled. * * @throws SQLException if a database access error occurs or this * Connection object within this <code>CachedRowSet</code> is in auto-commit mode * @see java.sql.Connection#setAutoCommit */ public void commit() throws SQLException; /** * Each <code>CachedRowSet</code> object's <code>SyncProvider</code> contains * a <code>Connection</code> object from the original <code>ResultSet</code> * or JDBC properties passed to it. * <p> * Undoes all changes made in the current transaction. This method * should be used only when auto-commit mode has been disabled. * * @throws SQLException if a database access error occurs or this Connection * object within this <code>CachedRowSet</code> is in auto-commit mode. */ public void rollback() throws SQLException; /** * Each <code>CachedRowSet</code> object's <code>SyncProvider</code> contains * a <code>Connection</code> object from the original <code>ResultSet</code> * or JDBC properties passed to it. * <p> * Undoes all changes made in the current transaction back to the last * <code>Savepoint</code> transaction marker. This method should be used only * when auto-commit mode has been disabled. * * @param s A <code>Savepoint</code> transaction marker * @throws SQLException if a database access error occurs or this Connection * object within this <code>CachedRowSet</code> is in auto-commit mode. */ public void rollback(Savepoint s) throws SQLException; /** * Causes the <code>CachedRowSet</code> object's <code>SyncProvider</code> * to commit the changes when <code>acceptChanges()</code> is called. If * set to false, the changes will <b>not</b> be committed until one of the * <code>CachedRowSet</code> interface transaction methods is called. * * @deprecated Because this field is final (it is part of an interface), * its value cannot be changed. * @see #commit * @see #rollback */ @Deprecated public static final boolean COMMIT_ON_ACCEPT_CHANGES = true; /** * Notifies registered listeners that a RowSet object in the given RowSetEvent * object has populated a number of additional rows. The <code>numRows</code> parameter * ensures that this event will only be fired every <code>numRow</code>. * <p> * The source of the event can be retrieved with the method event.getSource. * * @param event a <code>RowSetEvent</code> object that contains the * <code>RowSet</code> object that is the source of the events * @param numRows when populating, the number of rows interval on which the * <code>CachedRowSet</code> populated should fire; the default value * is zero; cannot be less than <code>fetchSize</code> or zero * @throws SQLException {@code numRows < 0 or numRows < getFetchSize() } */ public void rowSetPopulated(RowSetEvent event, int numRows) throws SQLException; /** * Populates this <code>CachedRowSet</code> object with data from * the given <code>ResultSet</code> object. While related to the <code>populate(ResultSet)</code> * method, an additional parameter is provided to allow starting position within * the <code>ResultSet</code> from where to populate the CachedRowSet * instance. * <P> * This method can be used as an alternative to the <code>execute</code> method when an * application has a connection to an open <code>ResultSet</code> object. * Using the method <code>populate</code> can be more efficient than using * the version of the <code>execute</code> method that takes no parameters * because it does not open a new connection and re-execute this * <code>CachedRowSet</code> object's command. Using the <code>populate</code> * method is more a matter of convenience when compared to using the version * of <code>execute</code> that takes a <code>ResultSet</code> object. * * @param startRow the position in the <code>ResultSet</code> from where to start * populating the records in this <code>CachedRowSet</code> * @param rs the <code>ResultSet</code> object containing the data * to be read into this <code>CachedRowSet</code> object * @throws SQLException if a null <code>ResultSet</code> object is supplied * or this <code>CachedRowSet</code> object cannot * retrieve the associated <code>ResultSetMetaData</code> object * @see #execute * @see #populate(ResultSet) * @see java.sql.ResultSet * @see java.sql.ResultSetMetaData */ public void populate(ResultSet rs, int startRow) throws SQLException; /** * Sets the <code>CachedRowSet</code> object's page-size. A <code>CachedRowSet</code> * may be configured to populate itself in page-size sized batches of rows. When * either <code>populate()</code> or <code>execute()</code> are called, the * <code>CachedRowSet</code> fetches an additional page according to the * original SQL query used to populate the RowSet. * * @param size the page-size of the <code>CachedRowSet</code> * @throws SQLException if an error occurs setting the <code>CachedRowSet</code> * page size or if the page size is less than 0. */ public void setPageSize(int size) throws SQLException; /** * Returns the page-size for the <code>CachedRowSet</code> object * * @return an <code>int</code> page size */ public int getPageSize(); /** * Increments the current page of the <code>CachedRowSet</code>. This causes * the <code>CachedRowSet</code> implementation to fetch the next page-size * rows and populate the RowSet, if remaining rows remain within scope of the * original SQL query used to populated the RowSet. * * @return true if more pages exist; false if this is the last page * @throws SQLException if an error occurs fetching the next page, or if this * method is called prematurely before populate or execute. */ public boolean nextPage() throws SQLException; /** * Decrements the current page of the <code>CachedRowSet</code>. This causes * the <code>CachedRowSet</code> implementation to fetch the previous page-size * rows and populate the RowSet. The amount of rows returned in the previous * page must always remain within scope of the original SQL query used to * populate the RowSet. * * @return true if the previous page is successfully retrieved; false if this * is the first page. * @throws SQLException if an error occurs fetching the previous page, or if * this method is called prematurely before populate or execute. */ public boolean previousPage() throws SQLException; }