/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.commons.proxy.factory.javassist;
import javassist.CannotCompileException;
import javassist.CtClass;
import javassist.CtConstructor;
import javassist.CtMethod;
import org.apache.commons.proxy.Interceptor;
import org.apache.commons.proxy.Invoker;
import org.apache.commons.proxy.ObjectProvider;
import org.apache.commons.proxy.exception.ProxyFactoryException;
import org.apache.commons.proxy.factory.util.AbstractProxyClassGenerator;
import org.apache.commons.proxy.factory.util.AbstractSubclassingProxyFactory;
import org.apache.commons.proxy.factory.util.ProxyClassCache;
import java.lang.reflect.Method;
/**
* A <a href="http://www.jboss.org/products/javassist">Javassist</a>-based {@link org.apache.commons.proxy.ProxyFactory}
* implementation.
* <p/>
* <b>Dependencies</b>: <ul> <li>Javassist version 3.0 or greater</li> </ul> </p>
*
* @author James Carman
* @since 1.0
*/
public class JavassistProxyFactory extends AbstractSubclassingProxyFactory
{
//----------------------------------------------------------------------------------------------------------------------
// Fields
//----------------------------------------------------------------------------------------------------------------------
private static final ProxyClassCache delegatingProxyClassCache = new ProxyClassCache(
new DelegatingProxyClassGenerator() );
private static final ProxyClassCache interceptorProxyClassCache = new ProxyClassCache(
new InterceptorProxyClassGenerator() );
private static final ProxyClassCache invocationHandlerProxyClassCache = new ProxyClassCache(
new InvokerProxyClassGenerator() );
//----------------------------------------------------------------------------------------------------------------------
// ProxyFactory Implementation
//----------------------------------------------------------------------------------------------------------------------
public Object createDelegatorProxy( ClassLoader classLoader, ObjectProvider targetProvider,
Class[] proxyClasses )
{
try
{
final Class clazz = delegatingProxyClassCache.getProxyClass( classLoader, proxyClasses );
return clazz.getConstructor( new Class[]{ ObjectProvider.class } )
.newInstance( new Object[]{ targetProvider } );
}
catch( Exception e )
{
throw new ProxyFactoryException( "Unable to instantiate proxy from generated proxy class.", e );
}
}
public Object createInterceptorProxy( ClassLoader classLoader, Object target, Interceptor interceptor,
Class[] proxyClasses )
{
try
{
final Class clazz = interceptorProxyClassCache.getProxyClass( classLoader, proxyClasses );
final Method[] methods = AbstractProxyClassGenerator.getImplementationMethods( proxyClasses );
return clazz.getConstructor( new Class[]{ Method[].class, Object.class, Interceptor.class } )
.newInstance( new Object[]{ methods, target, interceptor } );
}
catch( Exception e )
{
throw new ProxyFactoryException( "Unable to instantiate proxy class instance.", e );
}
}
public Object createInvokerProxy( ClassLoader classLoader, Invoker invoker,
Class[] proxyClasses )
{
try
{
final Class clazz = invocationHandlerProxyClassCache.getProxyClass( classLoader, proxyClasses );
final Method[] methods = AbstractProxyClassGenerator.getImplementationMethods( proxyClasses );
return clazz.getConstructor( new Class[]{ Method[].class, Invoker.class } )
.newInstance( new Object[]{ methods, invoker } );
}
catch( Exception e )
{
throw new ProxyFactoryException( "Unable to instantiate proxy from generated proxy class.", e );
}
}
//----------------------------------------------------------------------------------------------------------------------
// Inner Classes
//----------------------------------------------------------------------------------------------------------------------
private static class InvokerProxyClassGenerator extends AbstractProxyClassGenerator
{
public Class generateProxyClass( ClassLoader classLoader, Class[] proxyClasses )
{
try
{
final CtClass proxyClass = JavassistUtils.createClass( getSuperclass( proxyClasses ) );
final Method[] methods = getImplementationMethods( proxyClasses );
JavassistUtils.addInterfaces( proxyClass, toInterfaces( proxyClasses ) );
JavassistUtils.addField( Method[].class, "methods", proxyClass );
JavassistUtils.addField( Invoker.class, "invoker", proxyClass );
final CtConstructor proxyConstructor = new CtConstructor(
JavassistUtils.resolve(
new Class[]{ Method[].class, Invoker.class } ),
proxyClass );
proxyConstructor
.setBody( "{\n\tthis.methods = $1;\n\tthis.invoker = $2; }" );
proxyClass.addConstructor( proxyConstructor );
for( int i = 0; i < methods.length; ++i )
{
final CtMethod method = new CtMethod( JavassistUtils.resolve( methods[i].getReturnType() ),
methods[i].getName(),
JavassistUtils.resolve( methods[i].getParameterTypes() ),
proxyClass );
final String body = "{\n\t return ( $r ) invoker.invoke( this, methods[" + i +
"], $args );\n }";
method.setBody( body );
proxyClass.addMethod( method );
}
return proxyClass.toClass( classLoader );
}
catch( CannotCompileException e )
{
throw new ProxyFactoryException( "Could not compile class.", e );
}
}
}
private static class InterceptorProxyClassGenerator extends AbstractProxyClassGenerator
{
public Class generateProxyClass( ClassLoader classLoader, Class[] proxyClasses )
{
try
{
final CtClass proxyClass = JavassistUtils.createClass( getSuperclass( proxyClasses ) );
final Method[] methods = getImplementationMethods( proxyClasses );
JavassistUtils.addInterfaces( proxyClass, toInterfaces( proxyClasses ) );
JavassistUtils.addField( Method[].class, "methods", proxyClass );
JavassistUtils.addField( Object.class, "target", proxyClass );
JavassistUtils.addField( Interceptor.class, "interceptor", proxyClass );
final CtConstructor proxyConstructor = new CtConstructor(
JavassistUtils.resolve(
new Class[]{ Method[].class, Object.class, Interceptor.class } ),
proxyClass );
proxyConstructor
.setBody(
"{\n\tthis.methods = $1;\n\tthis.target = $2;\n\tthis.interceptor = $3; }" );
proxyClass.addConstructor( proxyConstructor );
for( int i = 0; i < methods.length; ++i )
{
final CtMethod method = new CtMethod( JavassistUtils.resolve( methods[i].getReturnType() ),
methods[i].getName(),
JavassistUtils.resolve( methods[i].getParameterTypes() ),
proxyClass );
final Class invocationClass = JavassistInvocation
.getMethodInvocationClass( classLoader, methods[i] );
final String body = "{\n\t return ( $r ) interceptor.intercept( new " + invocationClass.getName() +
"( methods[" + i + "], target, $args ) );\n }";
method.setBody( body );
proxyClass.addMethod( method );
}
return proxyClass.toClass( classLoader );
}
catch( CannotCompileException e )
{
throw new ProxyFactoryException( "Could not compile class.", e );
}
}
}
private static class DelegatingProxyClassGenerator extends AbstractProxyClassGenerator
{
public Class generateProxyClass( ClassLoader classLoader, Class[] proxyClasses )
{
try
{
final CtClass proxyClass = JavassistUtils.createClass( getSuperclass( proxyClasses ) );
JavassistUtils.addField( ObjectProvider.class, "provider", proxyClass );
final CtConstructor proxyConstructor = new CtConstructor(
JavassistUtils.resolve( new Class[]{ ObjectProvider.class } ),
proxyClass );
proxyConstructor.setBody( "{ this.provider = $1; }" );
proxyClass.addConstructor( proxyConstructor );
JavassistUtils.addInterfaces( proxyClass, toInterfaces( proxyClasses ) );
final Method[] methods = getImplementationMethods( proxyClasses );
for( int i = 0; i < methods.length; ++i )
{
final Method method = methods[i];
final CtMethod ctMethod = new CtMethod( JavassistUtils.resolve( method.getReturnType() ),
method.getName(),
JavassistUtils.resolve( method.getParameterTypes() ),
proxyClass );
final String body = "{ return ( $r ) ( ( " + method.getDeclaringClass().getName() +
" )provider.getObject() )." +
method.getName() + "($$); }";
ctMethod.setBody( body );
proxyClass.addMethod( ctMethod );
}
return proxyClass.toClass( classLoader );
}
catch( CannotCompileException e )
{
throw new ProxyFactoryException( "Could not compile class.", e );
}
}
}
}