SystemLogHandler


1   /*
2    *  Licensed to the Apache Software Foundation (ASF) under one or more
3    *  contributor license agreements.  See the NOTICE file distributed with
4    *  this work for additional information regarding copyright ownership.
5    *  The ASF licenses this file to You under the Apache License, Version 2.0
6    *  (the "License"); you may not use this file except in compliance with
7    *  the License.  You may obtain a copy 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,
13   *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   *  See the License for the specific language governing permissions and
15   *  limitations under the License.
16   */
17  
18  package org.apache.tomcat.util.log;
19  
20  import java.io.IOException  ;
21  import java.io.PrintStream  ;
22  import java.util.EmptyStackException  ;
23  import java.util.Stack  ;
24  
25  /**
26   * This helper class may be used to do sophisticated redirection of 
27   * System.out and System.err on a per Thread basis.
28   * 
29   * A stack is implemented per Thread so that nested startCapture
30   * and stopCapture can be used.
31   *
32   * @author Remy Maucherat
33   * @author Glenn L. Nielsen
34   */
35  public class SystemLogHandler extends PrintStream   {
36  
37  
38      // ----------------------------------------------------------- Constructors
39  
40  
41      /**
42       * Construct the handler to capture the output of the given steam.
43       */
44      public SystemLogHandler(PrintStream   wrapped) {
45          super(wrapped);
46          out = wrapped;
47      }
48  
49  
50      // ----------------------------------------------------- Instance Variables
51  
52  
53      /**
54       * Wrapped PrintStream.
55       */
56      protected PrintStream   out = null;
57  
58  
59      /**
60       * Thread <-> CaptureLog associations.
61       */
62      protected static ThreadLocal   logs = new ThreadLocal  ();
63  
64  
65      /**
66       * Spare CaptureLog ready for reuse.
67       */
68      protected static Stack   reuse = new Stack  ();
69  
70  
71      // --------------------------------------------------------- Public Methods
72  
73  
74      /**
75       * Start capturing thread's output.
76       */
77      public static void startCapture() {
78          CaptureLog log = null;
79          if (!reuse.isEmpty()) {
80              try {
81                  log = (CaptureLog)reuse.pop();
82              } catch (EmptyStackException   e) {
83                  log = new CaptureLog();
84              }
85          } else {
86              log = new CaptureLog();
87          }
88          Stack   stack = (Stack  )logs.get();
89          if (stack == null) {
90              stack = new Stack  ();
91              logs.set(stack);
92          }
93          stack.push(log);
94      }
95  
96  
97      /**
98       * Stop capturing thread's output and return captured data as a String.
99       */
100     public static String   stopCapture() {
101         Stack   stack = (Stack  )logs.get();
102         if (stack == null || stack.isEmpty()) {
103             return null;
104         }
105         CaptureLog log = (CaptureLog)stack.pop();
106         if (log == null) {
107             return null;
108         }
109         String   capture = log.getCapture();
110         log.reset();
111         reuse.push(log);
112         return capture;
113     }
114 
115 
116     // ------------------------------------------------------ Protected Methods
117 
118 
119     /**
120      * Find PrintStream to which the output must be written to.
121      */
122     protected PrintStream   findStream() {
123         Stack   stack = (Stack  )logs.get();
124         if (stack != null && !stack.isEmpty()) {
125             CaptureLog log = (CaptureLog)stack.peek();
126             if (log != null) {
127                 PrintStream   ps = log.getStream();
128                 if (ps != null) {
129                     return ps;
130                 }
131             }
132         }
133         return out;
134     }
135 
136 
137     // ---------------------------------------------------- PrintStream Methods
138 
139 
140     public void flush() {
141         findStream().flush();
142     }
143 
144     public void close() {
145         findStream().close();
146     }
147 
148     public boolean checkError() {
149         return findStream().checkError();
150     }
151 
152     protected void setError() {
153         //findStream().setError();
154     }
155 
156     public void write(int b) {
157         findStream().write(b);
158     }
159 
160     public void write(byte[] b)
161         throws IOException   {
162         findStream().write(b);
163     }
164 
165     public void write(byte[] buf, int off, int len) {
166         findStream().write(buf, off, len);
167     }
168 
169     public void print(boolean b) {
170         findStream().print(b);
171     }
172 
173     public void print(char c) {
174         findStream().print(c);
175     }
176 
177     public void print(int i) {
178         findStream().print(i);
179     }
180 
181     public void print(long l) {
182         findStream().print(l);
183     }
184 
185     public void print(float f) {
186         findStream().print(f);
187     }
188 
189     public void print(double d) {
190         findStream().print(d);
191     }
192 
193     public void print(char[] s) {
194         findStream().print(s);
195     }
196 
197     public void print(String   s) {
198         findStream().print(s);
199     }
200 
201     public void print(Object   obj) {
202         findStream().print(obj);
203     }
204 
205     public void println() {
206         findStream().println();
207     }
208 
209     public void println(boolean x) {
210         findStream().println(x);
211     }
212 
213     public void println(char x) {
214         findStream().println(x);
215     }
216 
217     public void println(int x) {
218         findStream().println(x);
219     }
220 
221     public void println(long x) {
222         findStream().println(x);
223     }
224 
225     public void println(float x) {
226         findStream().println(x);
227     }
228 
229     public void println(double x) {
230         findStream().println(x);
231     }
232 
233     public void println(char[] x) {
234         findStream().println(x);
235     }
236 
237     public void println(String   x) {
238         findStream().println(x);
239     }
240 
241     public void println(Object   x) {
242         findStream().println(x);
243     }
244 
245 }
246
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