UserTransactionHelper


1   
2   /* 
3    * Copyright 2004-2005 OpenSymphony 
4    * 
5    * Licensed under the Apache License, Version 2.0 (the "License"); you may not 
6    * use this file except in compliance with the License. You may obtain a copy 
7    * of the License at 
8    * 
9    *   http://www.apache.org/licenses/LICENSE-2.0 
10   *   
11   * Unless required by applicable law or agreed to in writing, software 
12   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 
13   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 
14   * License for the specific language governing permissions and limitations 
15   * under the License.
16   * 
17   */
18  
19  /*
20   * Previously Copyright (c) 2001-2004 James House
21   */
22  package org.quartz.ee.jta;
23  
24  import javax.naming.InitialContext  ;
25  import javax.transaction.HeuristicMixedException  ;
26  import javax.transaction.HeuristicRollbackException  ;
27  import javax.transaction.NotSupportedException  ;
28  import javax.transaction.RollbackException  ;
29  import javax.transaction.SystemException  ;
30  import javax.transaction.UserTransaction  ;
31  
32  import org.apache.commons.logging.Log;
33  import org.apache.commons.logging.LogFactory;
34  import org.quartz.SchedulerException;
35  
36  /**
37   * <p>
38   * A helper for obtaining a handle to a UserTransaction...
39   * </p>
40   * <p>
41   * To ensure proper cleanup of the InitalContext used to create/lookup
42   * the UserTransaction, be sure to always call returnUserTransaction() when
43   * you are done with the UserTransaction. 
44   * </p>
45   * 
46   * @author James House
47   */
48  public class UserTransactionHelper {
49      
50      /*
51       * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
52       * 
53       * Constants.
54       * 
55       * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
56       */
57  
58      public static final String   DEFAULT_USER_TX_LOCATION = "java:comp/UserTransaction";
59  
60      /*
61       * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
62       * 
63       * Data members.
64       * 
65       * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
66       */
67  
68      private static String   userTxURL = DEFAULT_USER_TX_LOCATION;
69  
70      /*
71       * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
72       * 
73       * Constructors.
74       * 
75       * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
76       */
77  
78      /**
79       * Do not allow the creation of an all static utility class.
80       */
81      private UserTransactionHelper() {
82      }
83  
84      /*
85       * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
86       * 
87       * Interface.
88       * 
89       * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
90       */
91  
92      public static String   getUserTxLocation() {
93          return userTxURL;
94      }
95  
96      /**
97       * Set the JNDI URL at which the Application Server's UserTransaction can
98       * be found. If not set, the default value is "java:comp/UserTransaction" -
99       * which works for nearly all application servers.
100      */
101     public static void setUserTxLocation(String   userTxURL) {
102         if (userTxURL != null) {
103             UserTransactionHelper.userTxURL = userTxURL;
104         }
105     }
106 
107     /**
108      * Create/Lookup a UserTransaction in the InitialContext via the
109      * name set in setUserTxLocation().
110      */
111     public static UserTransaction   lookupUserTransaction() throws SchedulerException {
112         return new UserTransactionWithContext();
113     }
114     
115     /**
116      * Return a UserTransaction that was retrieved via getUserTransaction().
117      * This will make sure that the InitalContext used to lookup/create the 
118      * UserTransaction is properly cleaned up.
119      */
120     public static void returnUserTransaction(UserTransaction   userTransaction) {
121         if ((userTransaction != null) && 
122             (userTransaction instanceof UserTransactionWithContext)) {
123             UserTransactionWithContext userTransactionWithContext = 
124                 (UserTransactionWithContext)userTransaction;
125             
126             userTransactionWithContext.closeContext();
127         }
128     }
129 
130     /**
131      * This class wraps a UserTransaction with the InitialContext that was used
132      * to look it up, so that when the UserTransaction is returned to the 
133      * UserTransactionHelper the InitialContext can be closed.
134      */
135     private static class UserTransactionWithContext implements UserTransaction   {
136         InitialContext   context;
137         UserTransaction   userTransaction;
138         
139         public UserTransactionWithContext() throws SchedulerException {
140             try {
141                 context = new InitialContext  ();
142             } catch (Throwable   t) {
143                 throw new SchedulerException(
144                     "UserTransactionHelper failed to create InitialContext to lookup/create UserTransaction.", t);
145             }
146             
147             try {
148                 userTransaction = (UserTransaction  )context.lookup(userTxURL);
149             } catch (Throwable   t) {
150                 closeContext();
151                 throw new SchedulerException(
152                     "UserTransactionHelper could not lookup/create UserTransaction.",
153                     t);
154             }
155             
156             if (userTransaction == null) {
157                 closeContext();
158                 throw new SchedulerException(
159                     "UserTransactionHelper could not lookup/create UserTransaction from the InitialContext.");
160             }
161         }
162 
163         /**
164          * Close the InitialContext that was used to lookup/create the
165          * underlying UserTransaction.
166          */
167         public void closeContext() {
168             try {
169                 if (context != null) {
170                     context.close();
171                 }
172             } catch (Throwable   t) {
173                 getLog().warn("Failed to close InitialContext used to get a UserTransaction.", t);
174             }
175             context = null;
176         }
177 
178         /**
179          * When we are being garbage collected, make sure we were properly
180          * returned to the UserTransactionHelper.
181          */
182         protected void finalize() throws Throwable   {
183             try {
184                 if (context != null) {
185                     getLog().warn("UserTransaction was never returned to the UserTransactionHelper.");
186                     closeContext();
187                 }
188             } finally {
189                 super.finalize();
190             }
191         }
192 
193         private static Log getLog() {
194             return LogFactory.getLog(UserTransactionWithContext.class);
195         }
196         
197         // Wrapper methods that just delegate to the underlying UserTransaction
198         
199         public void begin() throws NotSupportedException  , SystemException   {
200             userTransaction.begin();
201         }
202 
203         public void commit() throws RollbackException  , HeuristicMixedException  , HeuristicRollbackException  , SecurityException  , IllegalStateException  , SystemException   {
204             userTransaction.commit();        
205         }
206 
207         public void rollback() throws IllegalStateException  , SecurityException  , SystemException   {
208             userTransaction.rollback();
209         }
210 
211         public void setRollbackOnly() throws IllegalStateException  , SystemException   {
212             userTransaction.setRollbackOnly();
213         }
214 
215         public int getStatus() throws SystemException   {
216             return userTransaction.getStatus();
217         }
218 
219         public void setTransactionTimeout(int seconds) throws SystemException   {
220             userTransaction.setTransactionTimeout(seconds);
221         }
222     }
223 }
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