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Java > Open Source Codes > com > google > gwt > dev > util > log > ThreadLocalTreeLoggerProxy


1 /*
2  * Copyright 2006 Google Inc.
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License"); you may not
5  * use this file except in compliance with the License. You may obtain a copy of
6  * 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, WITHOUT
12  * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
13  * License for the specific language governing permissions and limitations under
14  * the License.
15  */
16 package com.google.gwt.dev.util.log;
17
18 import com.google.gwt.core.ext.TreeLogger;
19
20 /**
21  * An internal implementation support class that creates a
22  * {@link com.google.gwt.server.internal.TreeLogger} that wraps another
23  * TreeLogger to allow for the underlying logger to be redirected per thread. It
24  * can be useful for situations where it is not practical to pass in a logger as
25  * a parameter, such as when interfacing with third-party classes.
26  */
27 public final class ThreadLocalTreeLoggerProxy implements TreeLogger {
28
29   private static final ThreadLocal JavaDoc perThreadLogger = new ThreadLocal JavaDoc();
30
31   public ThreadLocalTreeLoggerProxy() {
32     this(null);
33   }
34
35   public ThreadLocalTreeLoggerProxy(TreeLogger logger) {
36     set(logger);
37   }
38
39   /**
40    * Delegates the branch to the thread-local logger if one is present.
41    * Otherwise, the log entry is discarded and <code>this</code> is returned.
42    */
43   public TreeLogger branch(Type type, String JavaDoc msg, Throwable JavaDoc caught) {
44     TreeLogger logger = (TreeLogger) perThreadLogger.get();
45     if (logger != null) {
46       return logger.branch(type, msg, caught);
47     } else {
48       return this;
49     }
50   }
51
52   /**
53    * Delegates the check to the thread-local logger if one is present.
54    *
55    * @return relays the return value of the wrapped logger if one exists, or
56    * returns <code>false</code> otherwise
57    */
58   public boolean isLoggable(Type type) {
59     TreeLogger logger = (TreeLogger) perThreadLogger.get();
60     if (logger != null) {
61       return logger.isLoggable(type);
62     } else {
63       return false;
64     }
65   }
66
67   /**
68    * Delegates the log to the thread-local logger if one is present. Otherwise,
69    * the log entry is discarded.
70    */
71   public void log(Type type, String JavaDoc msg, Throwable JavaDoc caught) {
72     TreeLogger logger = (TreeLogger) perThreadLogger.get();
73     if (logger != null) {
74       logger.log(type, msg, caught);
75     }
76   }
77
78   /**
79    * Sets the logger to which calls are redirected for the current thread.
80    */
81   public void set(TreeLogger logger) {
82     perThreadLogger.set(logger);
83   }
84 }
85
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