Decorates a ResultSet with checks for a SQL NULL value on each getXXX method.
import java.io.InputStream;
import java.io.Reader;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.math.BigDecimal;
import java.net.URL;
import java.sql.Blob;
import java.sql.Clob;
import java.sql.Date;
import java.sql.Ref;
import java.sql.ResultSet;
import java.sql.Time;
import java.sql.Timestamp;
import java.util.HashMap;
import java.util.Map;
/**
* Decorates a <code>ResultSet</code> with checks for a SQL NULL value on each
* <code>getXXX</code> method. If a column value obtained by a
* <code>getXXX</code> method is not SQL NULL, the column value is returned.
* If the column value is SQL null, an alternate value is returned. The
* alternate value defaults to the Java <code>null</code> value, which can be
* overridden for instances of the class.
*
* <p>
* Usage example: <blockquote>
*
* <pre>
* Connection conn = // somehow get a connection
* Statement stmt = conn.createStatement();
* ResultSet rs = stmt.executeQuery("SELECT col1, col2 FROM table1");
*
* // Wrap the result set for SQL NULL checking
* SqlNullCheckedResultSet wrapper = new SqlNullCheckedResultSet(rs);
* wrapper.setNullString("---N/A---"); // Set null string
* wrapper.setNullInt(-999); // Set null integer
* rs = ProxyFactory.instance().createResultSet(wrapper);
*
* while (rs.next()) {
* // If col1 is SQL NULL, value returned will be "---N/A---"
* String col1 = rs.getString("col1");
* // If col2 is SQL NULL, value returned will be -999
* int col2 = rs.getInt("col2");
* }
* rs.close();
* </pre>
*
* </blockquote>
* </p>
* <p>
* Unlike some other classes in DbUtils, this class is NOT thread-safe.
* </p>
*/
public class SqlNullCheckedResultSet implements InvocationHandler {
/**
* Maps normal method names (ie. "getBigDecimal") to the corresponding null
* Method object (ie. getNullBigDecimal).
*/
private static final Map nullMethods = new HashMap();
static {
Method[] methods = SqlNullCheckedResultSet.class.getMethods();
for (int i = 0; i < methods.length; i++) {
String methodName = methods[i].getName();
if (methodName.startsWith("getNull")) {
String normalName = "get" + methodName.substring(7);
nullMethods.put(normalName, methods[i]);
}
}
}
private InputStream nullAsciiStream = null;
private BigDecimal nullBigDecimal = null;
private InputStream nullBinaryStream = null;
private Blob nullBlob = null;
private boolean nullBoolean = false;
private byte nullByte = 0;
private byte[] nullBytes = null;
private Reader nullCharacterStream = null;
private Clob nullClob = null;
private Date nullDate = null;
private double nullDouble = 0.0;
private float nullFloat = 0.0f;
private int nullInt = 0;
private long nullLong = 0;
private Object nullObject = null;
private Ref nullRef = null;
private short nullShort = 0;
private String nullString = null;
private Time nullTime = null;
private Timestamp nullTimestamp = null;
private URL nullURL = null;
/**
* The wrapped result.
*/
private final ResultSet rs;
/**
* Constructs a new instance of <code>SqlNullCheckedResultSet</code> to wrap
* the specified <code>ResultSet</code>.
*
* @param rs
* ResultSet to wrap
*/
public SqlNullCheckedResultSet(ResultSet rs) {
super();
this.rs = rs;
}
/**
* Returns the value when a SQL null is encountered as the result of invoking
* a <code>getAsciiStream</code> method.
*
* @return the value
*/
public InputStream getNullAsciiStream() {
return this.nullAsciiStream;
}
/**
* Returns the value when a SQL null is encountered as the result of invoking
* a <code>getBigDecimal</code> method.
*
* @return the value
*/
public BigDecimal getNullBigDecimal() {
return this.nullBigDecimal;
}
/**
* Returns the value when a SQL null is encountered as the result of invoking
* a <code>getBinaryStream</code> method.
*
* @return the value
*/
public InputStream getNullBinaryStream() {
return this.nullBinaryStream;
}
/**
* Returns the value when a SQL null is encountered as the result of invoking
* a <code>getBlob</code> method.
*
* @return the value
*/
public Blob getNullBlob() {
return this.nullBlob;
}
/**
* Returns the value when a SQL null is encountered as the result of invoking
* a <code>getBoolean</code> method.
*
* @return the value
*/
public boolean getNullBoolean() {
return this.nullBoolean;
}
/**
* Returns the value when a SQL null is encountered as the result of invoking
* a <code>getByte</code> method.
*
* @return the value
*/
public byte getNullByte() {
return this.nullByte;
}
/**
* Returns the value when a SQL null is encountered as the result of invoking
* a <code>getBytes</code> method.
*
* @return the value
*/
public byte[] getNullBytes() {
return this.nullBytes;
}
/**
* Returns the value when a SQL null is encountered as the result of invoking
* a <code>getCharacterStream</code> method.
*
* @return the value
*/
public Reader getNullCharacterStream() {
return this.nullCharacterStream;
}
/**
* Returns the value when a SQL null is encountered as the result of invoking
* a <code>getClob</code> method.
*
* @return the value
*/
public Clob getNullClob() {
return this.nullClob;
}
/**
* Returns the value when a SQL null is encountered as the result of invoking
* a <code>getDate</code> method.
*
* @return the value
*/
public Date getNullDate() {
return this.nullDate;
}
/**
* Returns the value when a SQL null is encountered as the result of invoking
* a <code>getDouble</code> method.
*
* @return the value
*/
public double getNullDouble() {
return this.nullDouble;
}
/**
* Returns the value when a SQL null is encountered as the result of invoking
* a <code>getFloat</code> method.
*
* @return the value
*/
public float getNullFloat() {
return this.nullFloat;
}
/**
* Returns the value when a SQL null is encountered as the result of invoking
* a <code>getInt</code> method.
*
* @return the value
*/
public int getNullInt() {
return this.nullInt;
}
/**
* Returns the value when a SQL null is encountered as the result of invoking
* a <code>getLong</code> method.
*
* @return the value
*/
public long getNullLong() {
return this.nullLong;
}
/**
* Returns the value when a SQL null is encountered as the result of invoking
* a <code>getObject</code> method.
*
* @return the value
*/
public Object getNullObject() {
return this.nullObject;
}
/**
* Returns the value when a SQL null is encountered as the result of invoking
* a <code>getRef</code> method.
*
* @return the value
*/
public Ref getNullRef() {
return this.nullRef;
}
/**
* Returns the value when a SQL null is encountered as the result of invoking
* a <code>getShort</code> method.
*
* @return the value
*/
public short getNullShort() {
return this.nullShort;
}
/**
* Returns the value when a SQL null is encountered as the result of invoking
* a <code>getString</code> method.
*
* @return the value
*/
public String getNullString() {
return this.nullString;
}
/**
* Returns the value when a SQL null is encountered as the result of invoking
* a <code>getTime</code> method.
*
* @return the value
*/
public Time getNullTime() {
return this.nullTime;
}
/**
* Returns the value when a SQL null is encountered as the result of invoking
* a <code>getTimestamp</code> method.
*
* @return the value
*/
public Timestamp getNullTimestamp() {
return this.nullTimestamp;
}
/**
* Returns the value when a SQL null is encountered as the result of invoking
* a <code>getURL</code> method.
*
* @return the value
*/
public URL getNullURL() {
return this.nullURL;
}
/**
* Intercepts calls to <code>get*</code> methods and calls the appropriate
* <code>getNull*</code> method if the <code>ResultSet</code> returned
* <code>null</code>.
*
* @throws Throwable
* @see java.lang.reflect.InvocationHandler#invoke(java.lang.Object,
* java.lang.reflect.Method, java.lang.Object[])
*/
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
Object result = method.invoke(this.rs, args);
Method nullMethod = (Method) nullMethods.get(method.getName());
// Check nullMethod != null first so that we don't call wasNull()
// before a true getter method was invoked on the ResultSet.
return (nullMethod != null && this.rs.wasNull()) ? nullMethod.invoke(this, (Object[]) null)
: result;
}
/**
* Sets the value to return when a SQL null is encountered as the result of
* invoking a <code>getAsciiStream</code> method.
*
* @param nullAsciiStream
* the value
*/
public void setNullAsciiStream(InputStream nullAsciiStream) {
this.nullAsciiStream = nullAsciiStream;
}
/**
* Sets the value to return when a SQL null is encountered as the result of
* invoking a <code>getBigDecimal</code> method.
*
* @param nullBigDecimal
* the value
*/
public void setNullBigDecimal(BigDecimal nullBigDecimal) {
this.nullBigDecimal = nullBigDecimal;
}
/**
* Sets the value to return when a SQL null is encountered as the result of
* invoking a <code>getBinaryStream</code> method.
*
* @param nullBinaryStream
* the value
*/
public void setNullBinaryStream(InputStream nullBinaryStream) {
this.nullBinaryStream = nullBinaryStream;
}
/**
* Sets the value to return when a SQL null is encountered as the result of
* invoking a <code>getBlob</code> method.
*
* @param nullBlob
* the value
*/
public void setNullBlob(Blob nullBlob) {
this.nullBlob = nullBlob;
}
/**
* Sets the value to return when a SQL null is encountered as the result of
* invoking a <code>getBoolean</code> method.
*
* @param nullBoolean
* the value
*/
public void setNullBoolean(boolean nullBoolean) {
this.nullBoolean = nullBoolean;
}
/**
* Sets the value to return when a SQL null is encountered as the result of
* invoking a <code>getByte</code> method.
*
* @param nullByte
* the value
*/
public void setNullByte(byte nullByte) {
this.nullByte = nullByte;
}
/**
* Sets the value to return when a SQL null is encountered as the result of
* invoking a <code>getBytes</code> method.
*
* @param nullBytes
* the value
*/
public void setNullBytes(byte[] nullBytes) {
this.nullBytes = nullBytes;
}
/**
* Sets the value to return when a SQL null is encountered as the result of
* invoking a <code>getCharacterStream</code> method.
*
* @param nullCharacterStream
* the value
*/
public void setNullCharacterStream(Reader nullCharacterStream) {
this.nullCharacterStream = nullCharacterStream;
}
/**
* Sets the value to return when a SQL null is encountered as the result of
* invoking a <code>getClob</code> method.
*
* @param nullClob
* the value
*/
public void setNullClob(Clob nullClob) {
this.nullClob = nullClob;
}
/**
* Sets the value to return when a SQL null is encountered as the result of
* invoking a <code>getDate</code> method.
*
* @param nullDate
* the value
*/
public void setNullDate(Date nullDate) {
this.nullDate = nullDate;
}
/**
* Sets the value to return when a SQL null is encountered as the result of
* invoking a <code>getDouble</code> method.
*
* @param nullDouble
* the value
*/
public void setNullDouble(double nullDouble) {
this.nullDouble = nullDouble;
}
/**
* Sets the value to return when a SQL null is encountered as the result of
* invoking a <code>getFloat</code> method.
*
* @param nullFloat
* the value
*/
public void setNullFloat(float nullFloat) {
this.nullFloat = nullFloat;
}
/**
* Sets the value to return when a SQL null is encountered as the result of
* invoking a <code>getInt</code> method.
*
* @param nullInt
* the value
*/
public void setNullInt(int nullInt) {
this.nullInt = nullInt;
}
/**
* Sets the value to return when a SQL null is encountered as the result of
* invoking a <code>getLong</code> method.
*
* @param nullLong
* the value
*/
public void setNullLong(long nullLong) {
this.nullLong = nullLong;
}
/**
* Sets the value to return when a SQL null is encountered as the result of
* invoking a <code>getObject</code> method.
*
* @param nullObject
* the value
*/
public void setNullObject(Object nullObject) {
this.nullObject = nullObject;
}
/**
* Sets the value to return when a SQL null is encountered as the result of
* invoking a <code>getRef</code> method.
*
* @param nullRef
* the value
*/
public void setNullRef(Ref nullRef) {
this.nullRef = nullRef;
}
/**
* Sets the value to return when a SQL null is encountered as the result of
* invoking a <code>getShort</code> method.
*
* @param nullShort
* the value
*/
public void setNullShort(short nullShort) {
this.nullShort = nullShort;
}
/**
* Sets the value to return when a SQL null is encountered as the result of
* invoking a <code>getString</code> method.
*
* @param nullString
* the value
*/
public void setNullString(String nullString) {
this.nullString = nullString;
}
/**
* Sets the value to return when a SQL null is encountered as the result of
* invoking a <code>getTime</code> method.
*
* @param nullTime
* the value
*/
public void setNullTime(Time nullTime) {
this.nullTime = nullTime;
}
/**
* Sets the value to return when a SQL null is encountered as the result of
* invoking a <code>getTimestamp</code> method.
*
* @param nullTimestamp
* the value
*/
public void setNullTimestamp(Timestamp nullTimestamp) {
this.nullTimestamp = nullTimestamp;
}
/**
* Sets the value to return when a SQL null is encountered as the result of
* invoking a <code>getURL</code> method.
*
* @param nullURL
* the value
*/
public void setNullURL(URL nullURL) {
this.nullURL = nullURL;
}
}
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