EntityManagerProxyFactory.java

package org.needle4j.db.configuration;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;

import javax.persistence.EntityManager;

final class EntityManagerProxyFactory {

    private EntityManagerProxyFactory() {
        super();
    }

    static EntityManager createProxy(final EntityManager real) {
        return (EntityManager) Proxy.newProxyInstance(PersistenceConfigurationFactory.class.getClassLoader(),
                new Class[] { EntityManager.class }, new InvocationHandler() {
                    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
                        if (method.getName().equals("close")) {
                            throw new RuntimeException("you are not allowed to explicitely close this EntityManager");
                        }

                        try {
                            return method.invoke(real, args);
                        } catch (InvocationTargetException e) {
                            throw e.getCause();
                        }
                    }
                });
    }
}