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/*
* Copyright 2003,2004 The Apache Software Foundation
*
* Licensed 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 com.github.drinkjava2.cglib.proxy;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import com.github.drinkjava2.cglib.core.AbstractClassGenerator;
import com.github.drinkjava2.cglib.core.CodeGenerationException;
import com.github.drinkjava2.cglib.core.GeneratorStrategy;
import com.github.drinkjava2.cglib.core.NamingPolicy;
import com.github.drinkjava2.cglib.core.Signature;
import com.github.drinkjava2.cglib.reflect.FastClass;
/**
* Classes generated by {@link Enhancer} pass this object to the
* registered {@link MethodInterceptor} objects when an intercepted method is invoked. It can
* be used to either invoke the original method, or call the same method on a different
* object of the same type.
* @version $Id: MethodProxy.java,v 1.16 2009/01/11 20:09:48 herbyderby Exp $
*/
@SuppressWarnings({"rawtypes","unchecked" })
public class MethodProxy {
private Signature sig1;
private Signature sig2;
private CreateInfo createInfo;
private final Object initLock = new Object();
private volatile FastClassInfo fastClassInfo;
/**
* For internal use by {@link Enhancer} only; see the {@link com.github.drinkjava2.cglib.reflect.FastMethod} class
* for similar functionality.
*/
public static MethodProxy create(Class c1, Class c2, String desc, String name1, String name2) {
MethodProxy proxy = new MethodProxy();
proxy.sig1 = new Signature(name1, desc);
proxy.sig2 = new Signature(name2, desc);
proxy.createInfo = new CreateInfo(c1, c2);
return proxy;
}
private void init()
{
/*
* Using a volatile invariant allows us to initialize the FastClass and
* method index pairs atomically.
*
* Double-checked locking is safe with volatile in Java 5. Before 1.5 this
* code could allow fastClassInfo to be instantiated more than once, which
* appears to be benign.
*/
if (fastClassInfo == null)
{
synchronized (initLock)
{
if (fastClassInfo == null)
{
CreateInfo ci = createInfo;
FastClassInfo fci = new FastClassInfo();
fci.f1 = helper(ci, ci.c1);
fci.f2 = helper(ci, ci.c2);
fci.i1 = fci.f1.getIndex(sig1);
fci.i2 = fci.f2.getIndex(sig2);
fastClassInfo = fci;
createInfo = null;
}
}
}
}
private static class FastClassInfo
{
FastClass f1;
FastClass f2;
int i1;
int i2;
}
private static class CreateInfo
{
Class c1;
Class c2;
NamingPolicy namingPolicy;
GeneratorStrategy strategy;
boolean attemptLoad;
public CreateInfo(Class c1, Class c2)
{
this.c1 = c1;
this.c2 = c2;
AbstractClassGenerator fromEnhancer = AbstractClassGenerator.getCurrent();
if (fromEnhancer != null) {
namingPolicy = fromEnhancer.getNamingPolicy();
strategy = fromEnhancer.getStrategy();
attemptLoad = fromEnhancer.getAttemptLoad();
}
}
}
private static FastClass helper(CreateInfo ci, Class type) {
FastClass.Generator g = new FastClass.Generator();
g.setType(type);
g.setClassLoader(ci.c2.getClassLoader());
g.setNamingPolicy(ci.namingPolicy);
g.setStrategy(ci.strategy);
g.setAttemptLoad(ci.attemptLoad);
return g.create();
}
private MethodProxy() {
}
/**
* Return the signature of the proxied method.
*/
public Signature getSignature() {
return sig1;
}
/**
* Return the name of the synthetic method created by CGLIB which is
* used by {@link #invokeSuper} to invoke the superclass
* (non-intercepted) method implementation. The parameter types are
* the same as the proxied method.
*/
public String getSuperName() {
return sig2.getName();
}
/**
* Return the {@link com.github.drinkjava2.cglib.reflect.FastClass} method index
* for the method used by {@link #invokeSuper}. This index uniquely
* identifies the method within the generated proxy, and therefore
* can be useful to reference external metadata.
* @see #getSuperName
*/
public int getSuperIndex() {
init();
return fastClassInfo.i2;
}
// For testing
FastClass getFastClass() {
init();
return fastClassInfo.f1;
}
// For testing
FastClass getSuperFastClass() {
init();
return fastClassInfo.f2;
}
/**
* Return the MethodProxy used when intercepting the method
* matching the given signature.
* @param type the class generated by Enhancer
* @param sig the signature to match
* @return the MethodProxy instance, or null if no applicable matching method is found
* @throws IllegalArgumentException if the Class was not created by Enhancer or does not use a MethodInterceptor
*/
public static MethodProxy find(Class type, Signature sig) {
try {
Method m = type.getDeclaredMethod(MethodInterceptorGenerator.FIND_PROXY_NAME,
MethodInterceptorGenerator.FIND_PROXY_TYPES);
return (MethodProxy)m.invoke(null, new Object[]{ sig });
} catch (NoSuchMethodException e) {
throw new IllegalArgumentException("Class " + type + " does not use a MethodInterceptor");
} catch (IllegalAccessException e) {
throw new CodeGenerationException(e);
} catch (InvocationTargetException e) {
throw new CodeGenerationException(e);
}
}
/**
* Invoke the original method, on a different object of the same type.
* @param obj the compatible object; recursion will result if you use the object passed as the first
* argument to the MethodInterceptor (usually not what you want)
* @param args the arguments passed to the intercepted method; you may substitute a different
* argument array as long as the types are compatible
* @see MethodInterceptor#intercept
* @throws Throwable the bare exceptions thrown by the called method are passed through
* without wrapping in an InvocationTargetException
*/
public Object invoke(Object obj, Object[] args) throws Throwable {
try {
init();
FastClassInfo fci = fastClassInfo;
return fci.f1.invoke(fci.i1, obj, args);
} catch (InvocationTargetException e) {
throw e.getTargetException();
} catch (IllegalArgumentException e) {
if (fastClassInfo.i1 < 0)
throw new IllegalArgumentException("Protected method: " + sig1);
throw e;
}
}
/**
* Invoke the original (super) method on the specified object.
* @param obj the enhanced object, must be the object passed as the first
* argument to the MethodInterceptor
* @param args the arguments passed to the intercepted method; you may substitute a different
* argument array as long as the types are compatible
* @see MethodInterceptor#intercept
* @throws Throwable the bare exceptions thrown by the called method are passed through
* without wrapping in an InvocationTargetException
*/
public Object invokeSuper(Object obj, Object[] args) throws Throwable {
try {
init();
FastClassInfo fci = fastClassInfo;
return fci.f2.invoke(fci.i2, obj, args);
} catch (InvocationTargetException e) {
throw e.getTargetException();
}
}
}