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16 package org.apache.ibatis.executor.loader.javassist;
17
18 import java.lang.reflect.Method;
19 import java.util.List;
20 import java.util.Map;
21 import java.util.Set;
22 import java.util.concurrent.locks.ReentrantLock;
23
24 import javassist.util.proxy.MethodHandler;
25 import javassist.util.proxy.Proxy;
26 import javassist.util.proxy.ProxyFactory;
27
28 import org.apache.ibatis.executor.ExecutorException;
29 import org.apache.ibatis.executor.loader.AbstractEnhancedDeserializationProxy;
30 import org.apache.ibatis.executor.loader.AbstractSerialStateHolder;
31 import org.apache.ibatis.executor.loader.ResultLoaderMap;
32 import org.apache.ibatis.executor.loader.WriteReplaceInterface;
33 import org.apache.ibatis.io.Resources;
34 import org.apache.ibatis.logging.Log;
35 import org.apache.ibatis.logging.LogFactory;
36 import org.apache.ibatis.reflection.ExceptionUtil;
37 import org.apache.ibatis.reflection.factory.ObjectFactory;
38 import org.apache.ibatis.reflection.property.PropertyCopier;
39 import org.apache.ibatis.reflection.property.PropertyNamer;
40 import org.apache.ibatis.session.Configuration;
41
42
43
44
45 public class JavassistProxyFactory implements org.apache.ibatis.executor.loader.ProxyFactory {
46
47 private static final String FINALIZE_METHOD = "finalize";
48 private static final String WRITE_REPLACE_METHOD = "writeReplace";
49
50 public JavassistProxyFactory() {
51 try {
52 Resources.classForName("javassist.util.proxy.ProxyFactory");
53 } catch (Throwable e) {
54 throw new IllegalStateException(
55 "Cannot enable lazy loading because Javassist is not available. Add Javassist to your classpath.", e);
56 }
57 }
58
59 @Override
60 public Object createProxy(Object target, ResultLoaderMap lazyLoader, Configuration configuration,
61 ObjectFactory objectFactory, List<Class<?>> constructorArgTypes, List<Object> constructorArgs) {
62 return EnhancedResultObjectProxyImpl.createProxy(target, lazyLoader, configuration, objectFactory,
63 constructorArgTypes, constructorArgs);
64 }
65
66 public Object createDeserializationProxy(Object target, Map<String, ResultLoaderMap.LoadPair> unloadedProperties,
67 ObjectFactory objectFactory, List<Class<?>> constructorArgTypes, List<Object> constructorArgs) {
68 return EnhancedDeserializationProxyImpl.createProxy(target, unloadedProperties, objectFactory, constructorArgTypes,
69 constructorArgs);
70 }
71
72 static Object createStaticProxy(Class<?> type, MethodHandler callback, List<Class<?>> constructorArgTypes,
73 List<Object> constructorArgs) {
74
75 ProxyFactory enhancer = new ProxyFactory();
76 enhancer.setSuperclass(type);
77
78 try {
79 type.getDeclaredMethod(WRITE_REPLACE_METHOD);
80
81 if (LogHolder.log.isDebugEnabled()) {
82 LogHolder.log.debug(WRITE_REPLACE_METHOD + " method was found on bean " + type + ", make sure it returns this");
83 }
84 } catch (NoSuchMethodException e) {
85 enhancer.setInterfaces(new Class[] { WriteReplaceInterface.class });
86 } catch (SecurityException e) {
87
88 }
89
90 Object enhanced;
91 Class<?>[] typesArray = constructorArgTypes.toArray(new Class[constructorArgTypes.size()]);
92 Object[] valuesArray = constructorArgs.toArray(new Object[constructorArgs.size()]);
93 try {
94 enhanced = enhancer.create(typesArray, valuesArray);
95 } catch (Exception e) {
96 throw new ExecutorException("Error creating lazy proxy. Cause: " + e, e);
97 }
98 ((Proxy) enhanced).setHandler(callback);
99 return enhanced;
100 }
101
102 private static class EnhancedResultObjectProxyImpl implements MethodHandler {
103 private final Class<?> type;
104 private final ResultLoaderMap lazyLoader;
105 private final boolean aggressive;
106 private final Set<String> lazyLoadTriggerMethods;
107 private final ObjectFactory objectFactory;
108 private final List<Class<?>> constructorArgTypes;
109 private final List<Object> constructorArgs;
110 private final ReentrantLock lock = new ReentrantLock();
111
112 private EnhancedResultObjectProxyImpl(Class<?> type, ResultLoaderMap lazyLoader, Configuration configuration,
113 ObjectFactory objectFactory, List<Class<?>> constructorArgTypes, List<Object> constructorArgs) {
114 this.type = type;
115 this.lazyLoader = lazyLoader;
116 this.aggressive = configuration.isAggressiveLazyLoading();
117 this.lazyLoadTriggerMethods = configuration.getLazyLoadTriggerMethods();
118 this.objectFactory = objectFactory;
119 this.constructorArgTypes = constructorArgTypes;
120 this.constructorArgs = constructorArgs;
121 }
122
123 public static Object createProxy(Object target, ResultLoaderMap lazyLoader, Configuration configuration,
124 ObjectFactory objectFactory, List<Class<?>> constructorArgTypes, List<Object> constructorArgs) {
125 final Class<?> type = target.getClass();
126 EnhancedResultObjectProxyImpl callback = new EnhancedResultObjectProxyImpl(type, lazyLoader, configuration,
127 objectFactory, constructorArgTypes, constructorArgs);
128 Object enhanced = createStaticProxy(type, callback, constructorArgTypes, constructorArgs);
129 PropertyCopier.copyBeanProperties(type, target, enhanced);
130 return enhanced;
131 }
132
133 @Override
134 public Object invoke(Object enhanced, Method method, Method methodProxy, Object[] args) throws Throwable {
135 final String methodName = method.getName();
136 lock.lock();
137 try {
138 if (WRITE_REPLACE_METHOD.equals(methodName)) {
139 Object original;
140 if (constructorArgTypes.isEmpty()) {
141 original = objectFactory.create(type);
142 } else {
143 original = objectFactory.create(type, constructorArgTypes, constructorArgs);
144 }
145 PropertyCopier.copyBeanProperties(type, enhanced, original);
146 if (!lazyLoader.isEmpty()) {
147 return new JavassistSerialStateHolder(original, lazyLoader.getProperties(), objectFactory,
148 constructorArgTypes, constructorArgs);
149 } else {
150 return original;
151 }
152 }
153 if (!lazyLoader.isEmpty() && !FINALIZE_METHOD.equals(methodName)) {
154 if (aggressive || lazyLoadTriggerMethods.contains(methodName)) {
155 lazyLoader.loadAll();
156 } else if (PropertyNamer.isSetter(methodName)) {
157 final String property = PropertyNamer.methodToProperty(methodName);
158 lazyLoader.remove(property);
159 } else if (PropertyNamer.isGetter(methodName)) {
160 final String property = PropertyNamer.methodToProperty(methodName);
161 if (lazyLoader.hasLoader(property)) {
162 lazyLoader.load(property);
163 }
164 }
165 }
166 return methodProxy.invoke(enhanced, args);
167 } catch (Throwable t) {
168 throw ExceptionUtil.unwrapThrowable(t);
169 } finally {
170 lock.unlock();
171 }
172 }
173 }
174
175 private static class EnhancedDeserializationProxyImpl extends AbstractEnhancedDeserializationProxy
176 implements MethodHandler {
177
178 private EnhancedDeserializationProxyImpl(Class<?> type, Map<String, ResultLoaderMap.LoadPair> unloadedProperties,
179 ObjectFactory objectFactory, List<Class<?>> constructorArgTypes, List<Object> constructorArgs) {
180 super(type, unloadedProperties, objectFactory, constructorArgTypes, constructorArgs);
181 }
182
183 public static Object createProxy(Object target, Map<String, ResultLoaderMap.LoadPair> unloadedProperties,
184 ObjectFactory objectFactory, List<Class<?>> constructorArgTypes, List<Object> constructorArgs) {
185 final Class<?> type = target.getClass();
186 EnhancedDeserializationProxyImpl callback = new EnhancedDeserializationProxyImpl(type, unloadedProperties,
187 objectFactory, constructorArgTypes, constructorArgs);
188 Object enhanced = createStaticProxy(type, callback, constructorArgTypes, constructorArgs);
189 PropertyCopier.copyBeanProperties(type, target, enhanced);
190 return enhanced;
191 }
192
193 @Override
194 public Object invoke(Object enhanced, Method method, Method methodProxy, Object[] args) throws Throwable {
195 final Object o = super.invoke(enhanced, method, args);
196 return o instanceof AbstractSerialStateHolder ? o : methodProxy.invoke(o, args);
197 }
198
199 @Override
200 protected AbstractSerialStateHolder newSerialStateHolder(Object userBean,
201 Map<String, ResultLoaderMap.LoadPair> unloadedProperties, ObjectFactory objectFactory,
202 List<Class<?>> constructorArgTypes, List<Object> constructorArgs) {
203 return new JavassistSerialStateHolder(userBean, unloadedProperties, objectFactory, constructorArgTypes,
204 constructorArgs);
205 }
206 }
207
208 private static class LogHolder {
209 private static final Log log = LogFactory.getLog(JavassistProxyFactory.class);
210 }
211
212 }