org.hibernate.engine.jdbc.BlobProxy Maven / Gradle / Ivy
/*
* Hibernate, Relational Persistence for Idiomatic Java
*
* Copyright (c) 2009 by Red Hat Inc and/or its affiliates or by
* third-party contributors as indicated by either @author tags or express
* copyright attribution statements applied by the authors. All
* third-party contributions are distributed under license by Red Hat Inc.
*
* This copyrighted material is made available to anyone wishing to use, modify,
* copy, or redistribute it subject to the terms and conditions of the GNU
* Lesser General Public License, as published by the Free Software Foundation.
*
* This program 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 Lesser General Public License
* for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this distribution; if not, write to:
* Free Software Foundation, Inc.
* 51 Franklin Street, Fifth Floor
* Boston, MA 02110-1301 USA
*/
package org.hibernate.engine.jdbc;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.sql.Blob;
import java.sql.SQLException;
import java.io.InputStream;
import java.io.ByteArrayInputStream;
import java.io.IOException;
/**
* Manages aspects of proxying {@link Blob Blobs} for non-contextual creation, including proxy creation and
* handling proxy invocations.
*
* @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 InputStream stream;
private long length;
private boolean needsReset = false;
/**
* Ctor used to build {@link Blob} from byte array.
*
* @param bytes The byte array
* @see #generateProxy(byte[])
*/
private BlobProxy(byte[] bytes) {
this.stream = new ByteArrayInputStream( bytes );
this.length = bytes.length;
}
/**
* Ctor 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.stream = stream;
this.length = length;
}
private long getLength() {
return length;
}
private InputStream getStream() throws SQLException {
try {
if (needsReset) {
stream.reset();
}
}
catch ( IOException ioe) {
throw new SQLException("could not reset reader");
}
needsReset = true;
return stream;
}
/**
* {@inheritDoc}
*
* @throws UnsupportedOperationException if any methods other than {@link Blob#length()}
* or {@link Blob#getBinaryStream} are invoked.
*/
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
if ( "length".equals( method.getName() ) ) {
return new Long( getLength() );
}
if ( "getBinaryStream".equals( method.getName() ) && method.getParameterTypes().length == 0 ) {
return getStream();
}
if ( "free".equals( method.getName() ) ) {
stream.close();
return null;
}
if ( "toString".equals( method.getName() ) ) {
return this.toString();
}
if ( "equals".equals( method.getName() ) ) {
return Boolean.valueOf( proxy == args[0] );
}
if ( "hashCode".equals( method.getName() ) ) {
return new Integer( 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() {
ClassLoader cl = Thread.currentThread().getContextClassLoader();
if ( cl == null ) {
cl = BlobImplementer.class.getClassLoader();
}
return cl;
}
}