/*
* 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.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.sql.Blob;
import java.sql.SQLException;
import org.hibernate.engine.jdbc.internal.BinaryStreamImpl;
import org.hibernate.type.descriptor.java.DataHelper;
/**
* Manages aspects of proxying {@link Blob} references 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 BlobProxy implements InvocationHandler {
private static final Class[] PROXY_INTERFACES = new Class[] { Blob.class, BlobImplementer.class };
private BinaryStream binaryStream;
private boolean needsReset;
/**
* Constructor used to build {@link Blob} from byte array.
*
* @param bytes The byte array
* @see #generateProxy(byte[])
*/
private BlobProxy(byte[] bytes) {
binaryStream = new BinaryStreamImpl( bytes );
}
/**
* Constructor used to build {@link Blob} from a stream.
*
* @param stream The binary stream
* @param length The length of the stream
* @see #generateProxy(java.io.InputStream, long)
*/
private BlobProxy(InputStream stream, long length) {
this.binaryStream = new StreamBackedBinaryStream( stream, length );
}
private long getLength() {
return binaryStream.getLength();
}
private InputStream getStream() throws SQLException {
return getUnderlyingStream().getInputStream();
}
private BinaryStream getUnderlyingStream() throws SQLException {
resetIfNeeded();
return binaryStream;
}
private void resetIfNeeded() throws SQLException {
try {
if ( needsReset ) {
binaryStream.getInputStream().reset();
}
}
catch ( IOException ioe) {
throw new SQLException("could not reset reader");
}
needsReset = true;
}
/**
* {@inheritDoc}
*
* @throws UnsupportedOperationException if any methods other than
* {@link Blob#length}, {@link BlobImplementer#getUnderlyingStream},
* {@link Blob#getBinaryStream}, {@link Blob#getBytes}, {@link Blob#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 ( "getBinaryStream".equals( methodName ) ) {
if ( argCount == 0 ) {
return getStream();
}
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 getBinaryStream(long,int) that the start+length must not exceed the
// total length, however that is at odds with the getBytes(long,int) behavior.
throw new SQLException( "Length must be great-than-or-equal to zero." );
}
return DataHelper.subStream( getStream(), start-1, length );
}
}
if ( "getBytes".equals( methodName ) ) {
if ( argCount == 2 ) {
final long start = (Long) args[0];
if ( start < 1 ) {
throw new SQLException( "Start position 1-based; must be 1 or more." );
}
final int length = (Integer) args[1];
if ( length < 0 ) {
throw new SQLException( "Length must be great-than-or-equal to zero." );
}
return DataHelper.extractBytes( getStream(), start-1, length );
}
}
if ( "free".equals( methodName ) && argCount == 0 ) {
binaryStream.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( "Blob may not be manipulated from creating session" );
}
/**
* Generates a BlobImpl proxy using byte data.
*
* @param bytes The data to be created as a Blob.
*
* @return The generated proxy.
*/
public static Blob generateProxy(byte[] bytes) {
return (Blob) Proxy.newProxyInstance( getProxyClassLoader(), PROXY_INTERFACES, new BlobProxy( bytes ) );
}
/**
* Generates a BlobImpl proxy using a given number of bytes from an InputStream.
*
* @param stream The input stream of bytes to be created as a Blob.
* @param length The number of bytes from stream to be written to the Blob.
*
* @return The generated proxy.
*/
public static Blob generateProxy(InputStream stream, long length) {
return (Blob) Proxy.newProxyInstance( getProxyClassLoader(), PROXY_INTERFACES, new BlobProxy( stream, length ) );
}
/**
* Determines the appropriate class loader to which the generated proxy
* should be scoped.
*
* @return The class loader appropriate for proxy construction.
*/
private static ClassLoader getProxyClassLoader() {
return BlobImplementer.class.getClassLoader();
}
private static class StreamBackedBinaryStream implements BinaryStream {
private final InputStream stream;
private final long length;
private byte[] bytes;
private StreamBackedBinaryStream(InputStream stream, long length) {
this.stream = stream;
this.length = length;
}
@Override
public InputStream getInputStream() {
return stream;
}
@Override
public byte[] getBytes() {
if ( bytes == null ) {
bytes = DataHelper.extractBytes( stream );
}
return bytes;
}
@Override
public long getLength() {
return (int) length;
}
@Override
public void release() {
try {
stream.close();
}
catch (IOException ignore) {
}
}
}
}