Java tutorial
/* * Copyright (c) 2003, 2014, 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.serial; import java.sql.*; import java.util.Arrays; import java.util.Map; import sun.reflect.misc.ReflectUtil; /** * An input stream used for custom mapping user-defined types (UDTs). * An <code>SQLInputImpl</code> object is an input stream that contains a * stream of values that are the attributes of a UDT. * <p> * This class is used by the driver behind the scenes when the method * <code>getObject</code> is called on an SQL structured or distinct type * that has a custom mapping; a programmer never invokes * <code>SQLInputImpl</code> methods directly. They are provided here as a * convenience for those who write <code>RowSet</code> implementations. * <P> * The <code>SQLInputImpl</code> class provides a set of * reader methods analogous to the <code>ResultSet</code> getter * methods. These methods make it possible to read the values in an * <code>SQLInputImpl</code> object. * <P> * The method <code>wasNull</code> is used to determine whether the * the last value read was SQL <code>NULL</code>. * <P>When the method <code>getObject</code> is called with an * object of a class implementing the interface <code>SQLData</code>, * the JDBC driver calls the method <code>SQLData.getSQLType</code> * to determine the SQL type of the UDT being custom mapped. The driver * creates an instance of <code>SQLInputImpl</code>, populating it with the * attributes of the UDT. The driver then passes the input * stream to the method <code>SQLData.readSQL</code>, which in turn * calls the <code>SQLInputImpl</code> reader methods * to read the attributes from the input stream. * @since 1.5 * @see java.sql.SQLData */ public class SQLInputImpl implements SQLInput { /** * <code>true</code> if the last value returned was <code>SQL NULL</code>; * <code>false</code> otherwise. */ private boolean lastValueWasNull; /** * The current index into the array of SQL structured type attributes * that will be read from this <code>SQLInputImpl</code> object and * mapped to the fields of a class in the Java programming language. */ private int idx; /** * The array of attributes to be read from this stream. The order * of the attributes is the same as the order in which they were * listed in the SQL definition of the UDT. */ private Object attrib[]; /** * The type map to use when the method <code>readObject</code> * is invoked. This is a <code>java.util.Map</code> object in which * there may be zero or more entries. Each entry consists of the * fully qualified name of a UDT (the value to be mapped) and the * <code>Class</code> object for a class that implements * <code>SQLData</code> (the Java class that defines how the UDT * will be mapped). */ private Map<String, Class<?>> map; /** * Creates an <code>SQLInputImpl</code> object initialized with the * given array of attributes and the given type map. If any of the * attributes is a UDT whose name is in an entry in the type map, * the attribute will be mapped according to the corresponding * <code>SQLData</code> implementation. * * @param attributes an array of <code>Object</code> instances in which * each element is an attribute of a UDT. The order of the * attributes in the array is the same order in which * the attributes were defined in the UDT definition. * @param map a <code>java.util.Map</code> object containing zero or more * entries, with each entry consisting of 1) a <code>String</code> * giving the fully * qualified name of the UDT and 2) the <code>Class</code> object * for the <code>SQLData</code> implementation that defines how * the UDT is to be mapped * @throws SQLException if the <code>attributes</code> or the <code>map</code> * is a <code>null</code> value */ public SQLInputImpl(Object[] attributes, Map<String, Class<?>> map) throws SQLException { if ((attributes == null) || (map == null)) { throw new SQLException("Cannot instantiate a SQLInputImpl " + "object with null parameters"); } // assign our local reference to the attribute stream attrib = Arrays.copyOf(attributes, attributes.length); // init the index point before the head of the stream idx = -1; // set the map this.map = map; } /** * Retrieves the next attribute in this <code>SQLInputImpl</code> object * as an <code>Object</code> in the Java programming language. * * @return the next value in the input stream * as an <code>Object</code> in the Java programming language * @throws SQLException if the read position is located at an invalid * position or if there are no further values in the stream */ private Object getNextAttribute() throws SQLException { if (++idx >= attrib.length) { throw new SQLException("SQLInputImpl exception: Invalid read " + "position"); } else { lastValueWasNull = attrib[idx] == null; return attrib[idx]; } } //================================================================ // Methods for reading attributes from the stream of SQL data. // These methods correspond to the column-accessor methods of // java.sql.ResultSet. //================================================================ /** * Retrieves the next attribute in this <code>SQLInputImpl</code> object as * a <code>String</code> in the Java programming language. * <p> * This method does not perform type-safe checking to determine if the * returned type is the expected type; this responsibility is delegated * to the UDT mapping as defined by a <code>SQLData</code> * implementation. * * @return the next attribute in this <code>SQLInputImpl</code> object; * if the value is <code>SQL NULL</code>, return <code>null</code> * @throws SQLException if the read position is located at an invalid * position or if there are no further values in the stream. */ public String readString() throws SQLException { return (String) getNextAttribute(); } /** * Retrieves the next attribute in this <code>SQLInputImpl</code> object as * a <code>boolean</code> in the Java programming language. * <p> * This method does not perform type-safe checking to determine if the * returned type is the expected type; this responsibility is delegated * to the UDT mapping as defined by a <code>SQLData</code> * implementation. * * @return the next attribute in this <code>SQLInputImpl</code> object; * if the value is <code>SQL NULL</code>, return <code>null</code> * @throws SQLException if the read position is located at an invalid * position or if there are no further values in the stream. */ public boolean readBoolean() throws SQLException { Boolean attrib = (Boolean) getNextAttribute(); return (attrib == null) ? false : attrib.booleanValue(); } /** * Retrieves the next attribute in this <code>SQLInputImpl</code> object as * a <code>byte</code> in the Java programming language. * <p> * This method does not perform type-safe checking to determine if the * returned type is the expected type; this responsibility is delegated * to the UDT mapping as defined by a <code>SQLData</code> * implementation. * * @return the next attribute in this <code>SQLInputImpl</code> object; * if the value is <code>SQL NULL</code>, return <code>null</code> * @throws SQLException if the read position is located at an invalid * position or if there are no further values in the stream */ public byte readByte() throws SQLException { Byte attrib = (Byte) getNextAttribute(); return (attrib == null) ? 0 : attrib.byteValue(); } /** * Retrieves the next attribute in this <code>SQLInputImpl</code> object * as a <code>short</code> in the Java programming language. * <P> * This method does not perform type-safe checking to determine if the * returned type is the expected type; this responsibility is delegated * to the UDT mapping as defined by a <code>SQLData</code> implementation. * * @return the next attribute in this <code>SQLInputImpl</code> object; * if the value is <code>SQL NULL</code>, return <code>null</code> * @throws SQLException if the read position is located at an invalid * position or if there are no more values in the stream */ public short readShort() throws SQLException { Short attrib = (Short) getNextAttribute(); return (attrib == null) ? 0 : attrib.shortValue(); } /** * Retrieves the next attribute in this <code>SQLInputImpl</code> object * as an <code>int</code> in the Java programming language. * <P> * This method does not perform type-safe checking to determine if the * returned type is the expected type; this responsibility is delegated * to the UDT mapping as defined by a <code>SQLData</code> implementation. * * @return the next attribute in this <code>SQLInputImpl</code> object; * if the value is <code>SQL NULL</code>, return <code>null</code> * @throws SQLException if the read position is located at an invalid * position or if there are no more values in the stream */ public int readInt() throws SQLException { Integer attrib = (Integer) getNextAttribute(); return (attrib == null) ? 0 : attrib.intValue(); } /** * Retrieves the next attribute in this <code>SQLInputImpl</code> object * as a <code>long</code> in the Java programming language. * <P> * This method does not perform type-safe checking to determine if the * returned type is the expected type; this responsibility is delegated * to the UDT mapping as defined by a <code>SQLData</code> implementation. * * @return the next attribute in this <code>SQLInputImpl</code> object; * if the value is <code>SQL NULL</code>, return <code>null</code> * @throws SQLException if the read position is located at an invalid * position or if there are no more values in the stream */ public long readLong() throws SQLException { Long attrib = (Long) getNextAttribute(); return (attrib == null) ? 0 : attrib.longValue(); } /** * Retrieves the next attribute in this <code>SQLInputImpl</code> object * as a <code>float</code> in the Java programming language. * <P> * This method does not perform type-safe checking to determine if the * returned type is the expected type; this responsibility is delegated * to the UDT mapping as defined by a <code>SQLData</code> implementation. * * @return the next attribute in this <code>SQLInputImpl</code> object; * if the value is <code>SQL NULL</code>, return <code>null</code> * @throws SQLException if the read position is located at an invalid * position or if there are no more values in the stream */ public float readFloat() throws SQLException { Float attrib = (Float) getNextAttribute(); return (attrib == null) ? 0 : attrib.floatValue(); } /** * Retrieves the next attribute in this <code>SQLInputImpl</code> object * as a <code>double</code> in the Java programming language. * <P> * This method does not perform type-safe checking to determine if the * returned type is the expected type; this responsibility is delegated * to the UDT mapping as defined by a <code>SQLData</code> implementation. * * @return the next attribute in this <code>SQLInputImpl</code> object; * if the value is <code>SQL NULL</code>, return <code>null</code> * @throws SQLException if the read position is located at an invalid * position or if there are no more values in the stream */ public double readDouble() throws SQLException { Double attrib = (Double) getNextAttribute(); return (attrib == null) ? 0 : attrib.doubleValue(); } /** * Retrieves the next attribute in this <code>SQLInputImpl</code> object * as a <code>java.math.BigDecimal</code>. * <P> * This method does not perform type-safe checking to determine if the * returned type is the expected type; this responsibility is delegated * to the UDT mapping as defined by a <code>SQLData</code> implementation. * * @return the next attribute in this <code>SQLInputImpl</code> object; * if the value is <code>SQL NULL</code>, return <code>null</code> * @throws SQLException if the read position is located at an invalid * position or if there are no more values in the stream */ public java.math.BigDecimal readBigDecimal() throws SQLException { return (java.math.BigDecimal) getNextAttribute(); } /** * Retrieves the next attribute in this <code>SQLInputImpl</code> object * as an array of bytes. * <p> * This method does not perform type-safe checking to determine if the * returned type is the expected type; this responsibility is delegated * to the UDT mapping as defined by a <code>SQLData</code> implementation. * * @return the next attribute in this <code>SQLInputImpl</code> object; * if the value is <code>SQL NULL</code>, return <code>null</code> * @throws SQLException if the read position is located at an invalid * position or if there are no more values in the stream */ public byte[] readBytes() throws SQLException { return (byte[]) getNextAttribute(); } /** * Retrieves the next attribute in this <code>SQLInputImpl</code> as * a <code>java.sql.Date</code> object. * <P> * This method does not perform type-safe checking to determine if the * returned type is the expected type; this responsibility is delegated * to the UDT mapping as defined by a <code>SQLData</code> implementation. * * @return the next attribute in this <code>SQLInputImpl</code> object; * if the value is <code>SQL NULL</code>, return <code>null</code> * @throws SQLException if the read position is located at an invalid * position or if there are no more values in the stream */ public java.sql.Date readDate() throws SQLException { return (java.sql.Date) getNextAttribute(); } /** * Retrieves the next attribute in this <code>SQLInputImpl</code> object as * a <code>java.sql.Time</code> object. * <P> * This method does not perform type-safe checking to determine if the * returned type is the expected type as this responsibility is delegated * to the UDT mapping as implemented by a <code>SQLData</code> * implementation. * * @return the attribute; if the value is <code>SQL NULL</code>, return * <code>null</code> * @throws SQLException if the read position is located at an invalid * position; or if there are no further values in the stream. */ public java.sql.Time readTime() throws SQLException { return (java.sql.Time) getNextAttribute(); } /** * Retrieves the next attribute in this <code>SQLInputImpl</code> object as * a <code>java.sql.Timestamp</code> object. * * @return the attribute; if the value is <code>SQL NULL</code>, return * <code>null</code> * @throws SQLException if the read position is located at an invalid * position; or if there are no further values in the stream. */ public java.sql.Timestamp readTimestamp() throws SQLException { return (java.sql.Timestamp) getNextAttribute(); } /** * Retrieves the next attribute in this <code>SQLInputImpl</code> object * as a stream of Unicode characters. * <P> * This method does not perform type-safe checking to determine if the * returned type is the expected type as this responsibility is delegated * to the UDT mapping as implemented by a <code>SQLData</code> * implementation. * * @return the attribute; if the value is <code>SQL NULL</code>, return <code>null</code> * @throws SQLException if the read position is located at an invalid * position; or if there are no further values in the stream. */ public java.io.Reader readCharacterStream() throws SQLException { return (java.io.Reader) getNextAttribute(); } /** * Returns the next attribute in this <code>SQLInputImpl</code> object * as a stream of ASCII characters. * <P> * This method does not perform type-safe checking to determine if the * returned type is the expected type as this responsibility is delegated * to the UDT mapping as implemented by a <code>SQLData</code> * implementation. * * @return the attribute; if the value is <code>SQL NULL</code>, * return <code>null</code> * @throws SQLException if the read position is located at an invalid * position; or if there are no further values in the stream. */ public java.io.InputStream readAsciiStream() throws SQLException { return (java.io.InputStream) getNextAttribute(); } /** * Returns the next attribute in this <code>SQLInputImpl</code> object * as a stream of uninterpreted bytes. * <P> * This method does not perform type-safe checking to determine if the * returned type is the expected type as this responsibility is delegated * to the UDT mapping as implemented by a <code>SQLData</code> * implementation. * * @return the attribute; if the value is <code>SQL NULL</code>, return * <code>null</code> * @throws SQLException if the read position is located at an invalid * position; or if there are no further values in the stream. */ public java.io.InputStream readBinaryStream() throws SQLException { return (java.io.InputStream) getNextAttribute(); } //================================================================ // Methods for reading items of SQL user-defined types from the stream. //================================================================ /** * Retrieves the value at the head of this <code>SQLInputImpl</code> * object as an <code>Object</code> in the Java programming language. The * actual type of the object returned is determined by the default * mapping of SQL types to types in the Java programming language unless * there is a custom mapping, in which case the type of the object * returned is determined by this stream's type map. * <P> * The JDBC technology-enabled driver registers a type map with the stream * before passing the stream to the application. * <P> * When the datum at the head of the stream is an SQL <code>NULL</code>, * this method returns <code>null</code>. If the datum is an SQL * structured or distinct type with a custom mapping, this method * determines the SQL type of the datum at the head of the stream, * constructs an object of the appropriate class, and calls the method * <code>SQLData.readSQL</code> on that object. The <code>readSQL</code> * method then calls the appropriate <code>SQLInputImpl.readXXX</code> * methods to retrieve the attribute values from the stream. * * @return the value at the head of the stream as an <code>Object</code> * in the Java programming language; <code>null</code> if * the value is SQL <code>NULL</code> * @throws SQLException if the read position is located at an invalid * position; or if there are no further values in the stream. */ public Object readObject() throws SQLException { Object attrib = getNextAttribute(); if (attrib instanceof Struct) { Struct s = (Struct) attrib; // look up the class in the map Class<?> c = map.get(s.getSQLTypeName()); if (c != null) { // create new instance of the class SQLData obj = null; try { ReflectUtil.checkPackageAccess(c); @SuppressWarnings("deprecation") Object tmp = c.newInstance(); obj = (SQLData) tmp; } catch (Exception ex) { throw new SQLException("Unable to Instantiate: ", ex); } // get the attributes from the struct Object attribs[] = s.getAttributes(map); // create the SQLInput "stream" SQLInputImpl sqlInput = new SQLInputImpl(attribs, map); // read the values... obj.readSQL(sqlInput, s.getSQLTypeName()); return obj; } } return attrib; } /** * Retrieves the value at the head of this <code>SQLInputImpl</code> object * as a <code>Ref</code> object in the Java programming language. * * @return a <code>Ref</code> object representing the SQL * <code>REF</code> value at the head of the stream; if the value * is <code>SQL NULL</code> return <code>null</code> * @throws SQLException if the read position is located at an invalid * position; or if there are no further values in the stream. */ public Ref readRef() throws SQLException { return (Ref) getNextAttribute(); } /** * Retrieves the <code>BLOB</code> value at the head of this * <code>SQLInputImpl</code> object as a <code>Blob</code> object * in the Java programming language. * <P> * This method does not perform type-safe checking to determine if the * returned type is the expected type as this responsibility is delegated * to the UDT mapping as implemented by a <code>SQLData</code> * implementation. * * @return a <code>Blob</code> object representing the SQL * <code>BLOB</code> value at the head of this stream; * if the value is <code>SQL NULL</code>, return * <code>null</code> * @throws SQLException if the read position is located at an invalid * position; or if there are no further values in the stream. */ public Blob readBlob() throws SQLException { return (Blob) getNextAttribute(); } /** * Retrieves the <code>CLOB</code> value at the head of this * <code>SQLInputImpl</code> object as a <code>Clob</code> object * in the Java programming language. * <P> * This method does not perform type-safe checking to determine if the * returned type is the expected type as this responsibility is delegated * to the UDT mapping as implemented by a <code>SQLData</code> * implementation. * * @return a <code>Clob</code> object representing the SQL * <code>CLOB</code> value at the head of the stream; * if the value is <code>SQL NULL</code>, return * <code>null</code> * @throws SQLException if the read position is located at an invalid * position; or if there are no further values in the stream. */ public Clob readClob() throws SQLException { return (Clob) getNextAttribute(); } /** * Reads an SQL <code>ARRAY</code> value from the stream and * returns it as an <code>Array</code> object in the Java programming * language. * <P> * This method does not perform type-safe checking to determine if the * returned type is the expected type as this responsibility is delegated * to the UDT mapping as implemented by a <code>SQLData</code> * implementation. * * @return an <code>Array</code> object representing the SQL * <code>ARRAY</code> value at the head of the stream; * * if the value is <code>SQL NULL</code>, return * <code>null</code> * @throws SQLException if the read position is located at an invalid * position; or if there are no further values in the stream. */ public Array readArray() throws SQLException { return (Array) getNextAttribute(); } /** * Ascertains whether the last value read from this * <code>SQLInputImpl</code> object was <code>null</code>. * * @return <code>true</code> if the SQL value read most recently was * <code>null</code>; otherwise, <code>false</code>; by default it * will return false * @throws SQLException if an error occurs determining the last value * read was a <code>null</code> value or not; */ public boolean wasNull() throws SQLException { return lastValueWasNull; } /** * Reads an SQL <code>DATALINK</code> value from the stream and * returns it as an <code>URL</code> object in the Java programming * language. * <P> * This method does not perform type-safe checking to determine if the * returned type is the expected type as this responsibility is delegated * to the UDT mapping as implemented by a <code>SQLData</code> * implementation. * * @return an <code>URL</code> object representing the SQL * <code>DATALINK</code> value at the head of the stream; * * if the value is <code>SQL NULL</code>, return * <code>null</code> * @throws SQLException if the read position is located at an invalid * position; or if there are no further values in the stream. */ public java.net.URL readURL() throws SQLException { return (java.net.URL) getNextAttribute(); } //---------------------------- JDBC 4.0 ------------------------- /** * Reads an SQL <code>NCLOB</code> value from the stream and returns it as a * <code>Clob</code> object in the Java programming language. * * @return a <code>NClob</code> object representing data of the SQL <code>NCLOB</code> value * at the head of the stream; <code>null</code> if the value read is * SQL <code>NULL</code> * @exception SQLException if a database access error occurs * @since 1.6 */ public NClob readNClob() throws SQLException { return (NClob) getNextAttribute(); } /** * Reads the next attribute in the stream and returns it as a <code>String</code> * in the Java programming language. It is intended for use when * accessing <code>NCHAR</code>,<code>NVARCHAR</code> * and <code>LONGNVARCHAR</code> columns. * * @return the attribute; if the value is SQL <code>NULL</code>, returns <code>null</code> * @exception SQLException if a database access error occurs * @since 1.6 */ public String readNString() throws SQLException { return (String) getNextAttribute(); } /** * Reads an SQL <code>XML</code> value from the stream and returns it as a * <code>SQLXML</code> object in the Java programming language. * * @return a <code>SQLXML</code> object representing data of the SQL <code>XML</code> value * at the head of the stream; <code>null</code> if the value read is * SQL <code>NULL</code> * @exception SQLException if a database access error occurs * @since 1.6 */ public SQLXML readSQLXML() throws SQLException { return (SQLXML) getNextAttribute(); } /** * Reads an SQL <code>ROWID</code> value from the stream and returns it as a * <code>RowId</code> object in the Java programming language. * * @return a <code>RowId</code> object representing data of the SQL <code>ROWID</code> value * at the head of the stream; <code>null</code> if the value read is * SQL <code>NULL</code> * @exception SQLException if a database access error occurs * @since 1.6 */ public RowId readRowId() throws SQLException { return (RowId) getNextAttribute(); } }