package org.hibernate.proxy.pojo.javassist;
import java.io.Serializable;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import javassist.util.proxy.MethodFilter;
import javassist.util.proxy.MethodHandler;
import javassist.util.proxy.ProxyFactory;
import javassist.util.proxy.ProxyObject;
import org.apache.commons.logging.LogFactory;
import org.hibernate.HibernateException;
import org.hibernate.engine.SessionImplementor;
import org.hibernate.proxy.pojo.BasicLazyInitializer;
import org.hibernate.proxy.HibernateProxy;
import org.hibernate.type.AbstractComponentType;
import org.hibernate.util.ReflectHelper;
/**
* A Javassist-based lazy initializer proxy.
*
* @author Muga Nishizawa
*/
public class JavassistLazyInitializer extends BasicLazyInitializer implements MethodHandler {
private static final MethodFilter FINALIZE_FILTER = new MethodFilter() {
public boolean isHandled(Method m) {
// skip finalize methods
return !( m.getParameterTypes().length == 0 && m.getName().equals( "finalize" ) );
}
};
private Class[] interfaces;
private boolean constructed = false;
private JavassistLazyInitializer(
final String entityName,
final Class persistentClass,
final Class[] interfaces,
final Serializable id,
final Method getIdentifierMethod,
final Method setIdentifierMethod,
final AbstractComponentType componentIdType,
final SessionImplementor session) {
super( entityName, persistentClass, id, getIdentifierMethod, setIdentifierMethod, componentIdType, session );
this.interfaces = interfaces;
}
public static HibernateProxy getProxy(
final String entityName,
final Class persistentClass,
final Class[] interfaces,
final Method getIdentifierMethod,
final Method setIdentifierMethod,
AbstractComponentType componentIdType,
final Serializable id,
final SessionImplementor session) throws HibernateException {
// note: interface is assumed to already contain HibernateProxy.class
try {
final JavassistLazyInitializer instance = new JavassistLazyInitializer(
entityName,
persistentClass,
interfaces,
id,
getIdentifierMethod,
setIdentifierMethod,
componentIdType,
session
);
ProxyFactory factory = new ProxyFactory();
factory.setSuperclass( interfaces.length == 1 ? persistentClass : null );
factory.setInterfaces( interfaces );
factory.setFilter( FINALIZE_FILTER );
Class cl = factory.createClass();
final HibernateProxy proxy = ( HibernateProxy ) cl.newInstance();
( ( ProxyObject ) proxy ).setHandler( instance );
instance.constructed = true;
return proxy;
}
catch ( Throwable t ) {
LogFactory.getLog( BasicLazyInitializer.class ).error(
"Javassist Enhancement failed: " + entityName, t
);
throw new HibernateException(
"Javassist Enhancement failed: "
+ entityName, t
);
}
}
public static HibernateProxy getProxy(
final Class factory,
final String entityName,
final Class persistentClass,
final Class[] interfaces,
final Method getIdentifierMethod,
final Method setIdentifierMethod,
final AbstractComponentType componentIdType,
final Serializable id,
final SessionImplementor session) throws HibernateException {
final JavassistLazyInitializer instance = new JavassistLazyInitializer(
entityName,
persistentClass,
interfaces, id,
getIdentifierMethod,
setIdentifierMethod,
componentIdType,
session
);
final HibernateProxy proxy;
try {
proxy = ( HibernateProxy ) factory.newInstance();
}
catch ( Exception e ) {
throw new HibernateException(
"Javassist Enhancement failed: "
+ persistentClass.getName(), e
);
}
( ( ProxyObject ) proxy ).setHandler( instance );
instance.constructed = true;
return proxy;
}
public static Class getProxyFactory(
Class persistentClass,
Class[] interfaces) throws HibernateException {
// note: interfaces is assumed to already contain HibernateProxy.class
try {
ProxyFactory factory = new ProxyFactory();
factory.setSuperclass( interfaces.length == 1 ? persistentClass : null );
factory.setInterfaces( interfaces );
factory.setFilter( FINALIZE_FILTER );
return factory.createClass();
}
catch ( Throwable t ) {
LogFactory.getLog( BasicLazyInitializer.class ).error(
"Javassist Enhancement failed: "
+ persistentClass.getName(), t
);
throw new HibernateException(
"Javassist Enhancement failed: "
+ persistentClass.getName(), t
);
}
}
public Object invoke(
final Object proxy,
final Method thisMethod,
final Method proceed,
final Object[] args) throws Throwable {
if ( this.constructed ) {
Object result;
try {
result = this.invoke( thisMethod, args, proxy );
}
catch ( Throwable t ) {
throw new Exception( t.getCause() );
}
if ( result == INVOKE_IMPLEMENTATION ) {
Object target = getImplementation();
final Object returnValue;
try {
if ( ReflectHelper.isPublic( persistentClass, thisMethod ) ) {
if ( ! thisMethod.getDeclaringClass().isInstance( target ) ) {
throw new ClassCastException( target.getClass().getName() );
}
returnValue = thisMethod.invoke( target, args );
}
else {
if ( !thisMethod.isAccessible() ) {
thisMethod.setAccessible( true );
}
returnValue = thisMethod.invoke( target, args );
}
return returnValue == target ? proxy : returnValue;
}
catch ( InvocationTargetException ite ) {
throw ite.getTargetException();
}
}
else {
return result;
}
}
else {
// while constructor is running
if ( thisMethod.getName().equals( "getHibernateLazyInitializer" ) ) {
return this;
}
else {
return proceed.invoke( proxy, args );
}
}
}
protected Object serializableProxy() {
return new SerializableProxy(
getEntityName(),
persistentClass,
interfaces,
getIdentifier(),
getIdentifierMethod,
setIdentifierMethod,
componentIdType
);
}
}