我目前正在为Hibernate迁移一个旧工具，以基于实体统计信息自动进行预取。旧工具使用了Hibernate 3.1，因此需要完成一些工作。传统上，Hibernate使用CGlib代理，但是当我为最新版本的Hibernate开发时，我正在将代理生成更改为ByteBuddy。
但是，自从更改为ByteBuddy以来，我在使MethodHandler正常工作时遇到了一些问题。我工具中的methodhandler应该可以处理对代理的所有调用，以收集必要的统计信息。目前，我的方法处理程序如下所示：
public class EntityProxyMethodHandler implements ProxyConfiguration.Interceptor, Serializable {
private final EntityTracker entityTracker;
private final Object proxiedObject;
private final String proxiedClassName;
EntityProxyMethodHandler(
Object proxiedObject,
String proxiedClassName,
Set<Property> persistentProperties,
ExtentManager extentManager) {
this.proxiedObject = proxiedObject;
this.proxiedClassName = proxiedClassName;
this.entityTracker = new EntityTracker(persistentProperties, extentManager );
}
@Override
@RuntimeType
public Object intercept(@This Object instance, @Origin Method method, @AllArguments Object[] arguments)
throws Exception {
final String methodName = method.getName();
if ( "toString".equals( methodName ) ) {
return proxiedClassName + "@" + System.identityHashCode( instance );
}
else if ( "equals".equals( methodName ) ) {
return proxiedObject == instance;
}
else if ( "hashCode".equals( methodName ) ) {
return System.identityHashCode( instance );
}
else if ( arguments.length == 0 ) {
switch ( methodName ) {
case "disableTracking": {
boolean oldValue = entityTracker.isTracking();
entityTracker.setTracking( false );
return oldValue;
}
case "enableTracking": {
boolean oldValue = entityTracker.isTracking();
entityTracker.setTracking( true );
return oldValue;
}
case "isAccessed":
return entityTracker.isAccessed();
default:
break;
}
}
else if ( arguments.length == 1 ) {
if ( methodName.equals( "addTracker" ) && method.getParameterTypes()[0].equals( Statistics.class ) ) {
entityTracker.addTracker( (Statistics) arguments[0] );
return null;
}
else if ( methodName.equals( "addTrackers" ) && method.getParameterTypes()[0].equals( Set.class ) ) {
@SuppressWarnings("unchecked")
Set<Statistics> newTrackers = (Set) arguments[0];
entityTracker.addTrackers( newTrackers );
return null;
}
else if ( methodName
.equals( "extendProfile" ) && method.getParameterTypes()[0].equals( Statistics.class ) ) {
entityTracker.extendProfile( (Statistics) arguments[0], instance );
return null;
}
else if ( methodName
.equals( "removeTracker" ) && method.getParameterTypes()[0].equals( Statistics.class ) ) {
entityTracker.removeTracker( (Statistics) arguments[0] );
return null;
}
}
entityTracker.trackAccess( instance );
return method.invoke( instance, arguments ); // Gets stuck here, the method interception gets intercepted endlessly
}
代理工厂如下：
public class EntityProxyFactory {
private static SessionFactoryImplementor sessionFactory = AutofetchIntegrator.getSessionFactory();
private static final ConcurrentMap<Class<?>, Constructor<?>> entityConstructorMap = new ConcurrentHashMap<>();
private static <T> Constructor<T> getDefaultConstructor(Class<T> clazz) throws NoSuchMethodException {
Constructor<T> constructor = clazz.getDeclaredConstructor();
if ( !constructor.isAccessible() ) {
constructor.setAccessible( true );
}
return constructor;
}
static Object getProxyInstance(
Class persistentClass,
Set<Property> persistentProperties,
ExtentManager extentManager)
throws NoSuchMethodException, IllegalAccessException, InstantiationException, InvocationTargetException {
if ( Modifier.isFinal( persistentClass.getModifiers() ) ) {
// Use the default constructor, because final classes cannot be inherited.
return useDefaultConstructor( persistentClass );
}
final ProxyConfiguration proxy = (ProxyConfiguration) Environment.getBytecodeProvider()
.getProxyFactoryFactory()
.buildBasicProxyFactory( persistentClass, new Class[] { TrackableEntity.class } )
.getProxy();
proxy.$$_hibernate_set_interceptor( new EntityProxyMethodHandler(proxy,persistentClass.getName(),
persistentProperties,
extentManager
) );
return proxy;
}
private static Object useDefaultConstructor(Class<?> clazz)
throws NoSuchMethodException, IllegalAccessException, InvocationTargetException, InstantiationException {
if ( !entityConstructorMap.containsKey( clazz ) ) {
entityConstructorMap.put( clazz, getDefaultConstructor( clazz ) );
}
final Constructor<?> c = entityConstructorMap.get( clazz );
return c.newInstance();
}
}
当我运行包含访问代理字段之一的测试时，会得到如下的无穷调用堆栈：
EntityProxyMethodHandler.intercept(EntityProxyMethodHandler.java:105)
Employee.$HibernateBasicProxy$Rbz7NDpP.getSupervisor(Unknown Source)
Caused by java.lang.reflect.InvocationTargetException:
EntityProxyMethodHandler.intercept(EntityProxyMethodHandler.java:105)
Employee.$HibernateBasicProxy$Rbz7NDpP.getSupervisor(Unknown Source)
由于某种原因，它不调用真实实体，而是代理本身，陷入无尽的拦截循环中。我不知道如何解决此问题，我试图找到一种在方法处理程序中调用“目标”的方法，但由于某种原因，由于某种原因，代理工厂生成的代理未实现
此外，在我改用Javassist-proxies之前，此方法也可以正常工作。然后我有类似的课程：
public class EntityProxyFactory {
private static final CoreMessageLogger LOG = CoreLogging.messageLogger(AutofetchLazyInitializer.class);
private static final MethodFilter FINALIZE_FILTER = new MethodFilter() {
@Override
public boolean isHandled(Method m) {
// skip finalize methods
return !(m.getParameterTypes().length == 0 && m.getName().equals("finalize"));
}
};
private static final ConcurrentMap<Class<?>, Class<?>> entityFactoryMap = new ConcurrentHashMap<>();
private static final ConcurrentMap<Class<?>, Constructor<?>> entityConstructorMap = new ConcurrentHashMap<>();
//if entityFactoryMap doesnt contain that specific class, add it
private static Class<?> getProxyFactory(Class<?> persistentClass, String idMethodName) {
// Not sure how enhancer work, but it seems like you tell enhancer what type of subclasses that can be created, and all the method calls will be intercepted by entitycallbackfilter
if (!entityFactoryMap.containsKey(persistentClass)) {
ProxyFactory factory = new ProxyFactory();
factory.setSuperclass(persistentClass);
factory.setInterfaces(new Class[]{TrackableEntity.class});
factory.setFilter(FINALIZE_FILTER);
entityFactoryMap.putIfAbsent(persistentClass, factory.createClass());
}
return entityFactoryMap.get(persistentClass);
}
private static <T> Constructor<T> getDefaultConstructor(Class<T> clazz) throws NoSuchMethodException {
Constructor<T> constructor = clazz.getDeclaredConstructor();
if (!constructor.isAccessible()) {
constructor.setAccessible(true);
}
return constructor;
}
public static Object getProxyInstance(Class persistentClass, String idMethodName, Set<Property> persistentProperties,
ExtentManager extentManager)
throws InstantiationException, IllegalAccessException, NoSuchMethodException, InvocationTargetException {
if (Modifier.isFinal(persistentClass.getModifiers())) {
// Use the default constructor, because final classes cannot be inherited.
return useDefaultConstructor(persistentClass);
}
Class<?> factory = getProxyFactory(persistentClass, idMethodName);
try {
final Object proxy = factory.newInstance();
((Proxy) proxy).setHandler(new EntityProxyMethodHandler(persistentProperties, extentManager));
return proxy;
} catch (IllegalAccessException | InstantiationException e) {
return useDefaultConstructor(persistentClass);
}
}
private static Object useDefaultConstructor(Class<?> clazz) throws NoSuchMethodException, InstantiationException,
InvocationTargetException, IllegalAccessException {
if (!entityConstructorMap.containsKey(clazz)) {
entityConstructorMap.put(clazz, getDefaultConstructor(clazz));
}
final Constructor<?> c = entityConstructorMap.get(clazz);
return c.newInstance((Object[]) null);
}
}
public class EntityProxyMethodHandler implements MethodHandler, Serializable {
private final EntityTracker entityTracker;
public EntityProxyMethodHandler(Set<Property> persistentProperties, ExtentManager extentManager) {
this.entityTracker = new EntityTracker(persistentProperties, extentManager);
}
@Override
public Object invoke(Object obj, Method thisMethod, Method proceed, Object[] args) throws Throwable {
if (args.length == 0) {
if (thisMethod.getName().equals("disableTracking")) {
boolean oldValue = entityTracker.isTracking();
entityTracker.setTracking(false);
return oldValue;
} else if (thisMethod.getName().equals("enableTracking")) {
boolean oldValue = entityTracker.isTracking();
entityTracker.setTracking(true);
return oldValue;
} else if (thisMethod.getName().equals("isAccessed")) {
return entityTracker.isAccessed();
}
} else if (args.length == 1) {
if (thisMethod.getName().equals("addTracker") && thisMethod.getParameterTypes()[0].equals(Statistics.class)) {
entityTracker.addTracker((Statistics) args[0]);
return null;
} else if (thisMethod.getName().equals("addTrackers") && thisMethod.getParameterTypes()[0].equals(Set.class)) {
@SuppressWarnings("unchecked")
Set<Statistics> newTrackers = (Set) args[0];
entityTracker.addTrackers(newTrackers);
return null;
} else if (thisMethod.getName().equals("extendProfile") && thisMethod.getParameterTypes()[0].equals(Statistics.class)) {
entityTracker.extendProfile((Statistics) args[0], obj);
return null;
} else if (thisMethod.getName().equals("removeTracker") && thisMethod.getParameterTypes()[0].equals(Statistics.class)) {
entityTracker.removeTracker((Statistics) args[0]);
return null;
}
}
entityTracker.trackAccess(obj);
return proceed.invoke(obj, args);
}
有人知道我如何在这里的方法处理程序中调用真实实体对象吗？
这是我运行单元测试时堆栈tracea的一部分，由引起的是“无限地”重复的：
java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.autofetch.hibernate.EntityProxyMethodHandler.intercept(EntityProxyMethodHandler.java:105)
at org.autofetch.test.Employee$HibernateBasicProxy$dbvGRz97.getSupervisor(Unknown Source)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.autofetch.hibernate.AutofetchLazyInitializer.intercept(AutofetchLazyInitializer.java:123)
at org.hibernate.proxy.ProxyConfiguration$InterceptorDispatcher.intercept(ProxyConfiguration.java:95)
at org.autofetch.test.Employee$HibernateProxy$PajATc2c.getSupervisor(Unknown Source)
at org.autofetch.test.ExtentTest.secondLevelSupervisorAccess(ExtentTest.java:533)
at org.autofetch.test.ExtentTest.testSecondLevelSupervisorAccess(ExtentTest.java:246)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
at org.hibernate.testing.junit4.ExtendedFrameworkMethod.invokeExplosively(ExtendedFrameworkMethod.java:45)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:27)
at org.junit.internal.runners.statements.FailOnTimeout$CallableStatement.call(FailOnTimeout.java:298)
at org.junit.internal.runners.statements.FailOnTimeout$CallableStatement.call(FailOnTimeout.java:292)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.autofetch.hibernate.EntityProxyMethodHandler.intercept(EntityProxyMethodHandler.java:105)
at org.autofetch.test.Employee$HibernateBasicProxy$dbvGRz97.getSupervisor(Unknown Source)
... 30 more
答案 0 :(得分：1)
如果要调用原始方法，则可以使用@SuperMethod Method m或@SuperCall Callable<?> c来获取它。
使用可调用代理是开销最小的方法，这样做，您无需掌握参数数组。