2 * Copyright 2005-2010 the original author or authors.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
16 package org.wamblee.test.persistence;
19 import java.lang.reflect.InvocationHandler;
20 import java.lang.reflect.InvocationTargetException;
21 import java.lang.reflect.Method;
22 import java.lang.reflect.Proxy;
24 import javax.persistence.EntityManager;
26 import org.wamblee.test.persistence.JpaBuilder.JpaUnitOfWork;
27 import org.wamblee.test.transactions.ThreadSpecificProxyFactory;
30 * This utility makes sure that each invocation on a certain interface is
31 * carried out within a JPA unit of work. Note that this is equivalent
32 * to the sementics of a requiresNew transaction attribute.
34 * Use {@link #getTransactionScopedEntityManager()} to get the transaction
35 * scoped entity manager to pass to services.
40 * JpaBuilder builder = ...
41 * TransactionProxyFactory<Service> factory = new TransactionProxyFactory<Service>(
42 * builder, Service.class);
43 * Service service = new JpaService(factory.getTransactionScopedEntityManager());
44 * Service proxy = factory.getProxy(service);
45 * proxy.executeMethod(...);
47 * The above example executes the executeMethod() call on the service object within an active transaction.
48 * In the constructor of the service a transaction scoped entity manager is passed.
51 * Type of interface to proxy.
53 * @author Erik Brakkee
55 public class TransactionProxyFactory<T> {
58 * Executes the call on the service within a new transaction.
60 * @author Erik Brakkee
62 * @param <T> Type of the service interface.
64 private class UnitOfWorkInvocationHandler<T> implements InvocationHandler {
68 public UnitOfWorkInvocationHandler(T aService) {
73 public Object invoke(Object aProxy, final Method aMethod,
74 final Object[] aArgs) throws Throwable {
75 return TransactionProxyFactory.this.jpaBuilder
76 .execute(new JpaUnitOfWork<Object>() {
78 public Object execute(EntityManager aEm) throws Exception {
79 EntityManager oldEm = ENTITY_MANAGER.get();
81 ENTITY_MANAGER.set(aEm);
82 return aMethod.invoke(service, aArgs);
83 } catch (InvocationTargetException e) {
84 Throwable cause = e.getCause();
85 if (cause instanceof Exception) {
86 throw (Exception) cause;
87 } else if (cause instanceof Error) {
91 throw new RuntimeException(e);
93 ENTITY_MANAGER.set(oldEm);
101 private static final ThreadSpecificProxyFactory<EntityManager> ENTITY_MANAGER = new ThreadSpecificProxyFactory<EntityManager>(
102 EntityManager.class);
104 private JpaBuilder jpaBuilder;
105 private Class<T> clazz;
108 * Constructs the transaction proxy.
112 public TransactionProxyFactory(JpaBuilder aJpaBuilder, Class<T> aClass) {
113 jpaBuilder = aJpaBuilder;
117 public EntityManager getTransactionScopedEntityManager() {
118 return ENTITY_MANAGER.getProxy();
121 public T getProxy(T aService) {
122 InvocationHandler handler = new UnitOfWorkInvocationHandler<T>(aService);
123 Class proxyClass = Proxy.getProxyClass(clazz.getClassLoader(),
124 new Class[] { clazz });
127 proxy = (T) proxyClass.getConstructor(
128 new Class[] { InvocationHandler.class }).newInstance(
129 new Object[] { handler });
131 } catch (Exception e) {
132 throw new RuntimeException("Could not create proxy for " +