1 | /* |
2 | * Copyright 2006-2007 the original author or authors. |
3 | * |
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 |
7 | * |
8 | * http://www.apache.org/licenses/LICENSE-2.0 |
9 | * |
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. |
15 | */ |
16 | |
17 | package org.springframework.batch.support.transaction; |
18 | |
19 | import java.util.ArrayList; |
20 | import java.util.Collection; |
21 | import java.util.HashMap; |
22 | import java.util.HashSet; |
23 | import java.util.List; |
24 | import java.util.Map; |
25 | import java.util.Set; |
26 | |
27 | import org.aopalliance.intercept.MethodInterceptor; |
28 | import org.aopalliance.intercept.MethodInvocation; |
29 | import org.springframework.aop.framework.ProxyFactory; |
30 | import org.springframework.transaction.support.TransactionSynchronization; |
31 | import org.springframework.transaction.support.TransactionSynchronizationAdapter; |
32 | import org.springframework.transaction.support.TransactionSynchronizationManager; |
33 | |
34 | /** |
35 | * Factory for transaction aware objects (like lists, sets, maps). If a |
36 | * transaction is active when a method is called on an instance created by the |
37 | * factory, it makes a copy of the target object and carries out all operations |
38 | * on the copy. Only when the transaction commits is the target re-initialised |
39 | * with the copy.<br/> |
40 | * |
41 | * Works well with collections and maps for testing transactional behaviour |
42 | * without needing a database. The base implementation handles lists, sets and |
43 | * maps. Subclasses can implement {@link #begin(Object)} and |
44 | * {@link #commit(Object, Object)} to provide support for other resources. |
45 | * |
46 | * @author Dave Syer |
47 | * |
48 | */ |
49 | public class TransactionAwareProxyFactory { |
50 | |
51 | private Object target; |
52 | |
53 | public TransactionAwareProxyFactory(Object target) { |
54 | super(); |
55 | this.target = begin(target); |
56 | } |
57 | |
58 | /** |
59 | * Make a copy of the target that can be used inside a transaction to |
60 | * isolate changes from the original. Also called from the factory |
61 | * constructor to isolate the target from the original value passed in. |
62 | * |
63 | * @param target the target object (List, Set or Map) |
64 | * @return an independent copy |
65 | */ |
66 | protected final Object begin(Object target) { |
67 | if (target instanceof List) { |
68 | return new ArrayList((List) target); |
69 | } |
70 | else if (target instanceof Set) { |
71 | return new HashSet((Set) target); |
72 | } |
73 | else if (target instanceof Map) { |
74 | return new HashMap((Map) target); |
75 | } |
76 | else { |
77 | throw new UnsupportedOperationException("Cannot copy target for this type: " + target.getClass()); |
78 | } |
79 | } |
80 | |
81 | /** |
82 | * Take the working copy state and commit it back to the original target. |
83 | * The target then reflects all the changes applied to the copy during a |
84 | * transaction. |
85 | * |
86 | * @param copy the working copy. |
87 | * @param target the original target of the factory. |
88 | */ |
89 | protected void commit(Object copy, Object target) { |
90 | if (target instanceof Collection) { |
91 | ((Collection) target).clear(); |
92 | ((Collection) target).addAll((Collection) copy); |
93 | } |
94 | else { |
95 | ((Map) target).clear(); |
96 | ((Map) target).putAll((Map) copy); |
97 | } |
98 | } |
99 | |
100 | public Object createInstance() { |
101 | ProxyFactory factory = new ProxyFactory(target); |
102 | factory.addAdvice(new MethodInterceptor() { |
103 | public Object invoke(MethodInvocation invocation) throws Throwable { |
104 | |
105 | if (!TransactionSynchronizationManager.isActualTransactionActive()) { |
106 | return invocation.proceed(); |
107 | } |
108 | |
109 | Object cache; |
110 | |
111 | if (!TransactionSynchronizationManager.hasResource(this)) { |
112 | cache = begin(target); |
113 | TransactionSynchronizationManager.bindResource(this, cache); |
114 | TransactionSynchronizationManager.registerSynchronization(new TargetSynchronization(this, cache)); |
115 | } |
116 | else { |
117 | cache = TransactionSynchronizationManager.getResource(this); |
118 | } |
119 | |
120 | return invocation.getMethod().invoke(cache, invocation.getArguments()); |
121 | |
122 | } |
123 | }); |
124 | return factory.getProxy(); |
125 | } |
126 | |
127 | public static Map createTransactionalMap() { |
128 | return (Map) new TransactionAwareProxyFactory(new HashMap()).createInstance(); |
129 | } |
130 | |
131 | public static Set createTransactionalSet() { |
132 | return (Set) new TransactionAwareProxyFactory(new HashSet()).createInstance(); |
133 | } |
134 | |
135 | public static List createTransactionalList() { |
136 | return (List) new TransactionAwareProxyFactory(new ArrayList()).createInstance(); |
137 | } |
138 | |
139 | private class TargetSynchronization extends TransactionSynchronizationAdapter { |
140 | |
141 | Object cache; |
142 | |
143 | Object key; |
144 | |
145 | public TargetSynchronization(Object key, Object cache) { |
146 | super(); |
147 | this.cache = cache; |
148 | this.key = key; |
149 | } |
150 | |
151 | public void afterCompletion(int status) { |
152 | super.afterCompletion(status); |
153 | if (status == TransactionSynchronization.STATUS_COMMITTED) { |
154 | synchronized (target) { |
155 | commit(cache, target); |
156 | } |
157 | } |
158 | TransactionSynchronizationManager.unbindResource(key); |
159 | } |
160 | } |
161 | |
162 | } |