/*
* Hibernate, Relational Persistence for Idiomatic Java
*
* License: GNU Lesser General Public License (LGPL), version 2.1 or later.
* See the lgpl.txt file in the root directory or <http://www.gnu.org/licenses/lgpl-2.1.html>.
*/
package org.hibernate.engine.jdbc;
import java.io.IOException;
import java.io.InputStream;
import java.io.Reader;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.sql.Clob;
import java.sql.SQLException;
import org.hibernate.engine.jdbc.internal.CharacterStreamImpl;
import org.hibernate.type.descriptor.java.DataHelper;
/**
* Manages aspects of proxying {@link Clob Clobs} for non-contextual creation, including proxy creation and
* handling proxy invocations. We use proxies here solely to avoid JDBC version incompatibilities.
*
* @author Gavin King
* @author Steve Ebersole
* @author Gail Badner
*/
public class ClobProxy implements InvocationHandler {
private static final Class[] PROXY_INTERFACES = new Class[] { Clob.class, ClobImplementer.class };
private final CharacterStream characterStream;
private boolean needsReset;
/**
* Constructor used to build {@link Clob} from string data.
*
* @param string The byte array
* @see #generateProxy(String)
*/
protected ClobProxy(String string) {
this.characterStream = new CharacterStreamImpl( string );
}
/**
* Constructor used to build {@link Clob} from a reader.
*
* @param reader The character reader.
* @param length The length of the reader stream.
* @see #generateProxy(java.io.Reader, long)
*/
protected ClobProxy(Reader reader, long length) {
this.characterStream = new CharacterStreamImpl( reader, length );
}
protected long getLength() {
return characterStream.getLength();
}
protected InputStream getAsciiStream() throws SQLException {
return new ReaderInputStream( getCharacterStream() );
}
protected Reader getCharacterStream() throws SQLException {
return getUnderlyingStream().asReader();
}
protected CharacterStream getUnderlyingStream() throws SQLException {
resetIfNeeded();
return characterStream;
}
protected String getSubString(long start, int length) {
final String string = characterStream.asString();
// semi-naive implementation
final int endIndex = Math.min( ( (int) start ) + length, string.length() );
return string.substring( (int) start, endIndex );
}
/**
* {@inheritDoc}
*
* @throws UnsupportedOperationException if any methods other than {@link Clob#length},
* {@link Clob#getAsciiStream}, {@link Clob#getCharacterStream},
* {@link ClobImplementer#getUnderlyingStream}, {@link Clob#getSubString},
* {@link Clob#free}, or toString/equals/hashCode are invoked.
*/
@Override
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
final String methodName = method.getName();
final int argCount = method.getParameterCount();
if ( "length".equals( methodName ) && argCount == 0 ) {
return getLength();
}
if ( "getUnderlyingStream".equals( methodName ) ) {
return getUnderlyingStream(); // Reset stream if needed.
}
if ( "getAsciiStream".equals( methodName ) && argCount == 0 ) {
return getAsciiStream();
}
if ( "getCharacterStream".equals( methodName ) ) {
if ( argCount == 0 ) {
return getCharacterStream();
}
else if ( argCount == 2 ) {
final long start = (Long) args[0];
if ( start < 1 ) {
throw new SQLException( "Start position 1-based; must be 1 or more." );
}
if ( start > getLength() ) {
throw new SQLException( "Start position [" + start + "] cannot exceed overall CLOB length [" + getLength() + "]" );
}
final int length = (Integer) args[1];
if ( length < 0 ) {
// java docs specifically say for getCharacterStream(long,int) that the start+length must not exceed the
// total length, however that is at odds with the getSubString(long,int) behavior.
throw new SQLException( "Length must be great-than-or-equal to zero." );
}
return DataHelper.subStream( getCharacterStream(), start-1, length );
}
}
if ( "getSubString".equals( methodName ) && argCount == 2 ) {
final long start = (Long) args[0];
if ( start < 1 ) {
throw new SQLException( "Start position 1-based; must be 1 or more." );
}
if ( start > getLength() ) {
throw new SQLException( "Start position [" + start + "] cannot exceed overall CLOB length [" + getLength() + "]" );
}
final int length = (Integer) args[1];
if ( length < 0 ) {
throw new SQLException( "Length must be great-than-or-equal to zero." );
}
return getSubString( start-1, length );
}
if ( "free".equals( methodName ) && argCount == 0 ) {
characterStream.release();
return null;
}
if ( "toString".equals( methodName ) && argCount == 0 ) {
return this.toString();
}
if ( "equals".equals( methodName ) && argCount == 1 ) {
return proxy == args[0];
}
if ( "hashCode".equals( methodName ) && argCount == 0 ) {
return this.hashCode();
}
throw new UnsupportedOperationException( "Clob may not be manipulated from creating session" );
}
protected void resetIfNeeded() throws SQLException {
try {
if ( needsReset ) {
characterStream.asReader().reset();
}
}
catch ( IOException ioe ) {
throw new SQLException( "could not reset reader", ioe );
}
needsReset = true;
}
/**
* Generates a {@link Clob} proxy using the string data.
*
* @param string The data to be wrapped as a {@link Clob}.
*
* @return The generated proxy.
*/
public static Clob generateProxy(String string) {
return (Clob) Proxy.newProxyInstance( getProxyClassLoader(), PROXY_INTERFACES, new ClobProxy( string ) );
}
/**
* Generates a {@link Clob} proxy using a character reader of given length.
*
* @param reader The character reader
* @param length The length of the character reader
*
* @return The generated proxy.
*/
public static Clob generateProxy(Reader reader, long length) {
return (Clob) Proxy.newProxyInstance( getProxyClassLoader(), PROXY_INTERFACES, new ClobProxy( reader, length ) );
}
/**
* Determines the appropriate class loader to which the generated proxy
* should be scoped.
*
* @return The class loader appropriate for proxy construction.
*/
protected static ClassLoader getProxyClassLoader() {
return ClobImplementer.class.getClassLoader();
}
}