| /* |
| * 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.Invocation; |
| import org.apache.commons.proxy.ProxyUtils; |
| |
| import java.lang.ref.WeakReference; |
| import java.lang.reflect.Method; |
| import java.util.HashMap; |
| import java.util.Map; |
| import java.util.WeakHashMap; |
| |
| /** |
| * A <a href="http://www.jboss.org/products/javassist">Javassist</a>-based {@link Invocation} implementation. This |
| * class actually serves as the superclass for all <a href="http://www.jboss.org/products/javassist">Javassist</a>-based |
| * method invocations. Subclasses are dynamically created to deal with specific interface methods (they're hard-wired). |
| * |
| * @author James Carman |
| * @since 1.0 |
| */ |
| public abstract class JavassistInvocation implements Invocation |
| { |
| //********************************************************************************************************************** |
| // Fields |
| //********************************************************************************************************************** |
| |
| private static WeakHashMap loaderToClassCache = new WeakHashMap(); |
| protected final Method method; |
| protected final Object target; |
| protected final Object[] arguments; |
| |
| //********************************************************************************************************************** |
| // Static Methods |
| //********************************************************************************************************************** |
| |
| private static String createCastExpression( Class type, String objectToCast ) |
| { |
| if( !type.isPrimitive() ) |
| { |
| return "( " + ProxyUtils.getJavaClassName(type) + " )" + objectToCast; |
| } |
| else |
| { |
| return "( ( " + ProxyUtils.getWrapperClass(type).getName() + " )" + objectToCast + " )." + |
| type.getName() + "Value()"; |
| } |
| } |
| |
| private static Class createInvocationClass( ClassLoader classLoader, Method interfaceMethod ) |
| throws CannotCompileException |
| { |
| Class invocationClass; |
| final CtClass ctClass = JavassistUtils.createClass( |
| getSimpleName(interfaceMethod.getDeclaringClass()) + "_" + interfaceMethod.getName() + |
| "_invocation", |
| JavassistInvocation.class); |
| final CtConstructor constructor = new CtConstructor( |
| JavassistUtils.resolve(new Class[] {Method.class, Object.class, Object[].class}), |
| ctClass); |
| constructor.setBody("{\n\tsuper($$);\n}"); |
| ctClass.addConstructor(constructor); |
| final CtMethod proceedMethod = new CtMethod(JavassistUtils.resolve(Object.class), "proceed", |
| JavassistUtils.resolve(new Class[0]), ctClass); |
| final Class[] argumentTypes = interfaceMethod.getParameterTypes(); |
| final StringBuffer proceedBody = new StringBuffer("{\n"); |
| if( !Void.TYPE.equals(interfaceMethod.getReturnType()) ) |
| { |
| proceedBody.append("\treturn "); |
| if( interfaceMethod.getReturnType().isPrimitive() ) |
| { |
| proceedBody.append("new "); |
| proceedBody.append(ProxyUtils.getWrapperClass(interfaceMethod.getReturnType()).getName()); |
| proceedBody.append("( "); |
| } |
| } |
| else |
| { |
| proceedBody.append("\t"); |
| } |
| proceedBody.append("( ("); |
| proceedBody.append(ProxyUtils.getJavaClassName(interfaceMethod.getDeclaringClass())); |
| proceedBody.append(" )target )."); |
| proceedBody.append(interfaceMethod.getName()); |
| proceedBody.append("("); |
| for( int i = 0; i < argumentTypes.length; ++i ) |
| { |
| final Class argumentType = argumentTypes[i]; |
| proceedBody.append(createCastExpression(argumentType, "arguments[" + i + "]")); |
| if( i != argumentTypes.length - 1 ) |
| { |
| proceedBody.append(", "); |
| } |
| } |
| if( !Void.TYPE.equals(interfaceMethod.getReturnType()) && interfaceMethod.getReturnType().isPrimitive() ) |
| { |
| proceedBody.append(") );\n"); |
| } |
| else |
| { |
| proceedBody.append(");\n"); |
| } |
| if( Void.TYPE.equals(interfaceMethod.getReturnType()) ) |
| { |
| proceedBody.append("\treturn null;\n"); |
| } |
| proceedBody.append("}"); |
| final String body = proceedBody.toString(); |
| proceedMethod.setBody(body); |
| ctClass.addMethod(proceedMethod); |
| invocationClass = ctClass.toClass(classLoader); |
| return invocationClass; |
| } |
| |
| private static Map getClassCache( ClassLoader classLoader ) |
| { |
| Map cache = ( Map ) loaderToClassCache.get(classLoader); |
| if( cache == null ) |
| { |
| cache = new HashMap(); |
| loaderToClassCache.put(classLoader, cache); |
| } |
| return cache; |
| } |
| |
| /** |
| * Returns a method invocation class specifically coded to invoke the supplied interface method. |
| * |
| * @param classLoader the classloader to use |
| * @param interfaceMethod the interface method |
| * @return a method invocation class specifically coded to invoke the supplied interface method |
| * @throws CannotCompileException if a compilation error occurs |
| */ |
| synchronized static Class getMethodInvocationClass( ClassLoader classLoader, |
| Method interfaceMethod ) |
| throws CannotCompileException |
| { |
| final Map classCache = getClassCache(classLoader); |
| final String key = toClassCacheKey(interfaceMethod); |
| final WeakReference invocationClassRef = ( WeakReference ) classCache.get(key); |
| Class invocationClass; |
| if( invocationClassRef == null ) |
| { |
| invocationClass = createInvocationClass(classLoader, interfaceMethod); |
| classCache.put(key, new WeakReference(invocationClass)); |
| } |
| else |
| { |
| synchronized( invocationClassRef ) |
| { |
| invocationClass = ( Class ) invocationClassRef.get(); |
| if( invocationClass == null ) |
| { |
| invocationClass = createInvocationClass(classLoader, interfaceMethod); |
| classCache.put(key, new WeakReference(invocationClass)); |
| } |
| } |
| } |
| return invocationClass; |
| } |
| |
| private static String getSimpleName( Class c ) |
| { |
| final String name = c.getName(); |
| final int ndx = name.lastIndexOf('.'); |
| return ndx == -1 ? name : name.substring(ndx + 1); |
| } |
| |
| private static String toClassCacheKey( Method method ) |
| { |
| return String.valueOf(method); |
| } |
| |
| //********************************************************************************************************************** |
| // Constructors |
| //********************************************************************************************************************** |
| |
| public JavassistInvocation( Method method, Object target, Object[] arguments ) |
| { |
| this.method = method; |
| this.target = target; |
| this.arguments = arguments; |
| } |
| |
| //********************************************************************************************************************** |
| // Invocation Implementation |
| //********************************************************************************************************************** |
| |
| public Object[] getArguments() |
| { |
| return arguments; |
| } |
| |
| public Method getMethod() |
| { |
| return method; |
| } |
| |
| public Object getProxy() |
| { |
| return target; |
| } |
| } |
| |