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18 package org.apache.commons.proxy.factory.javassist;
19
20 import javassist.CannotCompileException;
21 import javassist.CtClass;
22 import javassist.CtConstructor;
23 import javassist.CtMethod;
24 import org.apache.commons.proxy.Interceptor;
25 import org.apache.commons.proxy.Invoker;
26 import org.apache.commons.proxy.ObjectProvider;
27 import org.apache.commons.proxy.exception.ProxyFactoryException;
28 import org.apache.commons.proxy.factory.util.AbstractProxyClassGenerator;
29 import org.apache.commons.proxy.factory.util.AbstractSubclassingProxyFactory;
30 import org.apache.commons.proxy.factory.util.ProxyClassCache;
31
32 import java.lang.reflect.Method;
33
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40
41
42
43 public class JavassistProxyFactory extends AbstractSubclassingProxyFactory
44 {
45
46
47
48 private static final ProxyClassCache delegatingProxyClassCache = new ProxyClassCache(
49 new DelegatingProxyClassGenerator() );
50 private static final ProxyClassCache interceptorProxyClassCache = new ProxyClassCache(
51 new InterceptorProxyClassGenerator() );
52 private static final ProxyClassCache invocationHandlerProxyClassCache = new ProxyClassCache(
53 new InvokerProxyClassGenerator() );
54
55
56
57
58
59 public Object createDelegatorProxy( ClassLoader classLoader, ObjectProvider targetProvider,
60 Class[] proxyClasses )
61 {
62 try
63 {
64 final Class clazz = delegatingProxyClassCache.getProxyClass( classLoader, proxyClasses );
65 return clazz.getConstructor( new Class[]{ ObjectProvider.class } )
66 .newInstance( new Object[]{ targetProvider } );
67 }
68 catch( Exception e )
69 {
70 throw new ProxyFactoryException( "Unable to instantiate proxy from generated proxy class.", e );
71 }
72 }
73
74 public Object createInterceptorProxy( ClassLoader classLoader, Object target, Interceptor interceptor,
75 Class[] proxyClasses )
76 {
77 try
78 {
79 final Class clazz = interceptorProxyClassCache.getProxyClass( classLoader, proxyClasses );
80 final Method[] methods = AbstractProxyClassGenerator.getImplementationMethods( proxyClasses );
81 return clazz.getConstructor( new Class[]{ Method[].class, Object.class, Interceptor.class } )
82 .newInstance( new Object[]{ methods, target, interceptor } );
83 }
84 catch( Exception e )
85 {
86 throw new ProxyFactoryException( "Unable to instantiate proxy class instance.", e );
87 }
88 }
89
90 public Object createInvokerProxy( ClassLoader classLoader, Invoker invoker,
91 Class[] proxyClasses )
92 {
93 try
94 {
95 final Class clazz = invocationHandlerProxyClassCache.getProxyClass( classLoader, proxyClasses );
96 final Method[] methods = AbstractProxyClassGenerator.getImplementationMethods( proxyClasses );
97 return clazz.getConstructor( new Class[]{ Method[].class, Invoker.class } )
98 .newInstance( new Object[]{ methods, invoker } );
99 }
100 catch( Exception e )
101 {
102 throw new ProxyFactoryException( "Unable to instantiate proxy from generated proxy class.", e );
103 }
104 }
105
106
107
108
109
110 private static class InvokerProxyClassGenerator extends AbstractProxyClassGenerator
111 {
112 public Class generateProxyClass( ClassLoader classLoader, Class[] proxyClasses )
113 {
114 try
115 {
116 final CtClass proxyClass = JavassistUtils.createClass( getSuperclass( proxyClasses ) );
117 final Method[] methods = getImplementationMethods( proxyClasses );
118 JavassistUtils.addInterfaces( proxyClass, toInterfaces( proxyClasses ) );
119 JavassistUtils.addField( Method[].class, "methods", proxyClass );
120 JavassistUtils.addField( Invoker.class, "invoker", proxyClass );
121 final CtConstructor proxyConstructor = new CtConstructor(
122 JavassistUtils.resolve(
123 new Class[]{ Method[].class, Invoker.class } ),
124 proxyClass );
125 proxyConstructor
126 .setBody( "{\n\tthis.methods = $1;\n\tthis.invoker = $2; }" );
127 proxyClass.addConstructor( proxyConstructor );
128 for( int i = 0; i < methods.length; ++i )
129 {
130 final CtMethod method = new CtMethod( JavassistUtils.resolve( methods[i].getReturnType() ),
131 methods[i].getName(),
132 JavassistUtils.resolve( methods[i].getParameterTypes() ),
133 proxyClass );
134 final String body = "{\n\t return ( $r ) invoker.invoke( this, methods[" + i +
135 "], $args );\n }";
136 method.setBody( body );
137 proxyClass.addMethod( method );
138 }
139 return proxyClass.toClass( classLoader );
140 }
141 catch( CannotCompileException e )
142 {
143 throw new ProxyFactoryException( "Could not compile class.", e );
144 }
145 }
146 }
147
148 private static class InterceptorProxyClassGenerator extends AbstractProxyClassGenerator
149 {
150 public Class generateProxyClass( ClassLoader classLoader, Class[] proxyClasses )
151 {
152 try
153 {
154 final CtClass proxyClass = JavassistUtils.createClass( getSuperclass( proxyClasses ) );
155 final Method[] methods = getImplementationMethods( proxyClasses );
156 JavassistUtils.addInterfaces( proxyClass, toInterfaces( proxyClasses ) );
157 JavassistUtils.addField( Method[].class, "methods", proxyClass );
158 JavassistUtils.addField( Object.class, "target", proxyClass );
159 JavassistUtils.addField( Interceptor.class, "interceptor", proxyClass );
160 final CtConstructor proxyConstructor = new CtConstructor(
161 JavassistUtils.resolve(
162 new Class[]{ Method[].class, Object.class, Interceptor.class } ),
163 proxyClass );
164 proxyConstructor
165 .setBody(
166 "{\n\tthis.methods = $1;\n\tthis.target = $2;\n\tthis.interceptor = $3; }" );
167 proxyClass.addConstructor( proxyConstructor );
168 for( int i = 0; i < methods.length; ++i )
169 {
170 final CtMethod method = new CtMethod( JavassistUtils.resolve( methods[i].getReturnType() ),
171 methods[i].getName(),
172 JavassistUtils.resolve( methods[i].getParameterTypes() ),
173 proxyClass );
174 final Class invocationClass = JavassistInvocation
175 .getMethodInvocationClass( classLoader, methods[i] );
176 final String body = "{\n\t return ( $r ) interceptor.intercept( new " + invocationClass.getName() +
177 "( methods[" + i + "], target, $args ) );\n }";
178 method.setBody( body );
179 proxyClass.addMethod( method );
180
181 }
182 return proxyClass.toClass( classLoader );
183 }
184 catch( CannotCompileException e )
185 {
186 throw new ProxyFactoryException( "Could not compile class.", e );
187 }
188 }
189 }
190
191 private static class DelegatingProxyClassGenerator extends AbstractProxyClassGenerator
192 {
193 public Class generateProxyClass( ClassLoader classLoader, Class[] proxyClasses )
194 {
195 try
196 {
197 final CtClass proxyClass = JavassistUtils.createClass( getSuperclass( proxyClasses ) );
198 JavassistUtils.addField( ObjectProvider.class, "provider", proxyClass );
199 final CtConstructor proxyConstructor = new CtConstructor(
200 JavassistUtils.resolve( new Class[]{ ObjectProvider.class } ),
201 proxyClass );
202 proxyConstructor.setBody( "{ this.provider = $1; }" );
203 proxyClass.addConstructor( proxyConstructor );
204 JavassistUtils.addInterfaces( proxyClass, toInterfaces( proxyClasses ) );
205 final Method[] methods = getImplementationMethods( proxyClasses );
206 for( int i = 0; i < methods.length; ++i )
207 {
208 final Method method = methods[i];
209 final CtMethod ctMethod = new CtMethod( JavassistUtils.resolve( method.getReturnType() ),
210 method.getName(),
211 JavassistUtils.resolve( method.getParameterTypes() ),
212 proxyClass );
213 final String body = "{ return ( $r ) ( ( " + method.getDeclaringClass().getName() +
214 " )provider.getObject() )." +
215 method.getName() + "($$); }";
216 ctMethod.setBody( body );
217 proxyClass.addMethod( ctMethod );
218
219 }
220 return proxyClass.toClass( classLoader );
221 }
222 catch( CannotCompileException e )
223 {
224 throw new ProxyFactoryException( "Could not compile class.", e );
225 }
226 }
227 }
228 }
229