【发布时间】：2018-07-31 11:52:06
【问题描述】：
我目前正在为 Hibernate 迁移一个旧工具，以根据实体统计信息自动预取。旧工具使用 Hibernate 3.1，所以还有一些工作要做。传统上，Hibernate 使用 CGlib 代理，但是当我为最新版本的 Hibernate 进行开发时，我将代理生成更改为 ByteBuddy。
但是，自从更改为 ByteBuddy 后，我在让 MethodHandler 工作时遇到了一些问题。我工具中的方法处理程序应该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
}
代理工厂如下所示：
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();
}
}
当我运行一个包含访问代理字段之一的测试时，我得到一个无穷无尽的调用堆栈：
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，它没有调用真实的实体，而是代理本身，陷入了无限的拦截循环。我不知道如何解决这个问题，我尝试找到一种在方法处理程序中调用“目标”的方法，但是由于某种原因代理工厂生成的代理没有实现 HibernateProxy-接口。也许这是 ByteBuddy 有一些方法可以处理的问题，但是由于我对框架相当缺乏经验，所以我还没有找到方法。
此外，在我使用 Javassist-proxies 之前，它可以完美运行。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);
}
有谁知道我如何在我的方法处理程序中调用真正的实体对象？
这是我运行单元测试时堆栈跟踪的一部分，导致“无限”重复：
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
【问题讨论】：
标签： java hibernate byte-buddy