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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
23 import javassist.util.proxy.MethodHandler;
24 import javassist.util.proxy.Proxy;
25 import javassist.util.proxy.ProxyFactory;
26
27 import org.apache.ibatis.executor.ExecutorException;
28 import org.apache.ibatis.executor.loader.AbstractEnhancedDeserializationProxy;
29 import org.apache.ibatis.executor.loader.AbstractSerialStateHolder;
30 import org.apache.ibatis.executor.loader.ResultLoaderMap;
31 import org.apache.ibatis.executor.loader.WriteReplaceInterface;
32 import org.apache.ibatis.io.Resources;
33 import org.apache.ibatis.logging.Log;
34 import org.apache.ibatis.logging.LogFactory;
35 import org.apache.ibatis.reflection.ExceptionUtil;
36 import org.apache.ibatis.reflection.factory.ObjectFactory;
37 import org.apache.ibatis.reflection.property.PropertyCopier;
38 import org.apache.ibatis.reflection.property.PropertyNamer;
39 import org.apache.ibatis.session.Configuration;
40
41
42
43
44 public class JavassistProxyFactory implements org.apache.ibatis.executor.loader.ProxyFactory {
45
46 private static final String FINALIZE_METHOD = "finalize";
47 private static final String WRITE_REPLACE_METHOD = "writeReplace";
48
49 public JavassistProxyFactory() {
50 try {
51 Resources.classForName("javassist.util.proxy.ProxyFactory");
52 } catch (Throwable e) {
53 throw new IllegalStateException("Cannot enable lazy loading because Javassist is not available. Add Javassist to your classpath.", e);
54 }
55 }
56
57 @Override
58 public Object createProxy(Object target, ResultLoaderMap lazyLoader, Configuration configuration, ObjectFactory objectFactory, List<Class<?>> constructorArgTypes, List<Object> constructorArgs) {
59 return EnhancedResultObjectProxyImpl.createProxy(target, lazyLoader, configuration, objectFactory, constructorArgTypes, constructorArgs);
60 }
61
62 public Object createDeserializationProxy(Object target, Map<String, ResultLoaderMap.LoadPair> unloadedProperties, ObjectFactory objectFactory, List<Class<?>> constructorArgTypes, List<Object> constructorArgs) {
63 return EnhancedDeserializationProxyImpl.createProxy(target, unloadedProperties, objectFactory, constructorArgTypes, constructorArgs);
64 }
65
66 static Object crateProxy(Class<?> type, MethodHandler callback, List<Class<?>> constructorArgTypes, List<Object> constructorArgs) {
67
68 ProxyFactoryder/ProxyFactory.html#ProxyFactory">ProxyFactory enhancer = new ProxyFactory();
69 enhancer.setSuperclass(type);
70
71 try {
72 type.getDeclaredMethod(WRITE_REPLACE_METHOD);
73
74 if (LogHolder.log.isDebugEnabled()) {
75 LogHolder.log.debug(WRITE_REPLACE_METHOD + " method was found on bean " + type + ", make sure it returns this");
76 }
77 } catch (NoSuchMethodException e) {
78 enhancer.setInterfaces(new Class[]{WriteReplaceInterface.class});
79 } catch (SecurityException e) {
80
81 }
82
83 Object enhanced;
84 Class<?>[] typesArray = constructorArgTypes.toArray(new Class[constructorArgTypes.size()]);
85 Object[] valuesArray = constructorArgs.toArray(new Object[constructorArgs.size()]);
86 try {
87 enhanced = enhancer.create(typesArray, valuesArray);
88 } catch (Exception e) {
89 throw new ExecutorException("Error creating lazy proxy. Cause: " + e, e);
90 }
91 ((Proxy) enhanced).setHandler(callback);
92 return enhanced;
93 }
94
95 private static class EnhancedResultObjectProxyImpl implements MethodHandler {
96
97 private final Class<?> type;
98 private final ResultLoaderMap lazyLoader;
99 private final boolean aggressive;
100 private final Set<String> lazyLoadTriggerMethods;
101 private final ObjectFactory objectFactory;
102 private final List<Class<?>> constructorArgTypes;
103 private final List<Object> constructorArgs;
104
105 private EnhancedResultObjectProxyImpl(Class<?> type, ResultLoaderMap lazyLoader, Configuration configuration, ObjectFactory objectFactory, List<Class<?>> constructorArgTypes, List<Object> constructorArgs) {
106 this.type = type;
107 this.lazyLoader = lazyLoader;
108 this.aggressive = configuration.isAggressiveLazyLoading();
109 this.lazyLoadTriggerMethods = configuration.getLazyLoadTriggerMethods();
110 this.objectFactory = objectFactory;
111 this.constructorArgTypes = constructorArgTypes;
112 this.constructorArgs = constructorArgs;
113 }
114
115 public static Object createProxy(Object target, ResultLoaderMap lazyLoader, Configuration configuration, ObjectFactory objectFactory, List<Class<?>> constructorArgTypes, List<Object> constructorArgs) {
116 final Class<?> type = target.getClass();
117 EnhancedResultObjectProxyImpl callback = new EnhancedResultObjectProxyImpl(type, lazyLoader, configuration, objectFactory, constructorArgTypes, constructorArgs);
118 Object enhanced = crateProxy(type, callback, constructorArgTypes, constructorArgs);
119 PropertyCopier.copyBeanProperties(type, target, enhanced);
120 return enhanced;
121 }
122
123 @Override
124 public Object invoke(Object enhanced, Method method, Method methodProxy, Object[] args) throws Throwable {
125 final String methodName = method.getName();
126 try {
127 synchronized (lazyLoader) {
128 if (WRITE_REPLACE_METHOD.equals(methodName)) {
129 Object original;
130 if (constructorArgTypes.isEmpty()) {
131 original = objectFactory.create(type);
132 } else {
133 original = objectFactory.create(type, constructorArgTypes, constructorArgs);
134 }
135 PropertyCopier.copyBeanProperties(type, enhanced, original);
136 if (lazyLoader.size() > 0) {
137 return new JavassistSerialStateHolder(original, lazyLoader.getProperties(), objectFactory, constructorArgTypes, constructorArgs);
138 } else {
139 return original;
140 }
141 } else {
142 if (lazyLoader.size() > 0 && !FINALIZE_METHOD.equals(methodName)) {
143 if (aggressive || lazyLoadTriggerMethods.contains(methodName)) {
144 lazyLoader.loadAll();
145 } else if (PropertyNamer.isSetter(methodName)) {
146 final String property = PropertyNamer.methodToProperty(methodName);
147 lazyLoader.remove(property);
148 } else if (PropertyNamer.isGetter(methodName)) {
149 final String property = PropertyNamer.methodToProperty(methodName);
150 if (lazyLoader.hasLoader(property)) {
151 lazyLoader.load(property);
152 }
153 }
154 }
155 }
156 }
157 return methodProxy.invoke(enhanced, args);
158 } catch (Throwable t) {
159 throw ExceptionUtil.unwrapThrowable(t);
160 }
161 }
162 }
163
164 private static class EnhancedDeserializationProxyImpl extends AbstractEnhancedDeserializationProxy implements MethodHandler {
165
166 private EnhancedDeserializationProxyImpl(Class<?> type, Map<String, ResultLoaderMap.LoadPair> unloadedProperties, ObjectFactory objectFactory,
167 List<Class<?>> constructorArgTypes, List<Object> constructorArgs) {
168 super(type, unloadedProperties, objectFactory, constructorArgTypes, constructorArgs);
169 }
170
171 public static Object createProxy(Object target, Map<String, ResultLoaderMap.LoadPair> unloadedProperties, ObjectFactory objectFactory,
172 List<Class<?>> constructorArgTypes, List<Object> constructorArgs) {
173 final Class<?> type = target.getClass();
174 EnhancedDeserializationProxyImpl callback = new EnhancedDeserializationProxyImpl(type, unloadedProperties, objectFactory, constructorArgTypes, constructorArgs);
175 Object enhanced = crateProxy(type, callback, constructorArgTypes, constructorArgs);
176 PropertyCopier.copyBeanProperties(type, target, enhanced);
177 return enhanced;
178 }
179
180 @Override
181 public Object invoke(Object enhanced, Method method, Method methodProxy, Object[] args) throws Throwable {
182 final Object o = super.invoke(enhanced, method, args);
183 return o instanceof AbstractSerialStateHolder ? o : methodProxy.invoke(o, args);
184 }
185
186 @Override
187 protected AbstractSerialStateHolder newSerialStateHolder(Object userBean, Map<String, ResultLoaderMap.LoadPair> unloadedProperties, ObjectFactory objectFactory,
188 List<Class<?>> constructorArgTypes, List<Object> constructorArgs) {
189 return new JavassistSerialStateHolder(userBean, unloadedProperties, objectFactory, constructorArgTypes, constructorArgs);
190 }
191 }
192
193 private static class LogHolder {
194 private static final Log log = LogFactory.getLog(JavassistProxyFactory.class);
195 }
196
197 }