WriterTarget


1   /* 
2    * Copyright 1999-2004 The Apache Software Foundation
3    * Licensed  under the  Apache License,  Version 2.0  (the "License");
4    * you may not use  this file  except in  compliance with the License.
5    * You may obtain a copy of the License at 
6    * 
7    *   http://www.apache.org/licenses/LICENSE-2.0
8    * 
9    * Unless required by applicable law or agreed to in writing, software
10   * distributed  under the  License is distributed on an "AS IS" BASIS,
11   * WITHOUT  WARRANTIES OR CONDITIONS  OF ANY KIND, either  express  or
12   * implied.
13   * 
14   * See the License for the specific language governing permissions and
15   * limitations under the License.
16   */
17  package org.apache.log.output.io;
18  
19  import java.io.IOException  ;
20  import java.io.Writer  ;
21  import org.apache.log.format.Formatter;
22  import org.apache.log.output.AbstractOutputTarget;
23  
24  /**
25   * This target outputs to a writer.
26   *
27   * @author Peter Donald
28   */
29  public class WriterTarget
30      extends AbstractOutputTarget
31  {
32      private Writer   m_output;
33  
34      /**
35       * Construct target with a specific writer and formatter.
36       *
37       * @param writer the writer
38       * @param formatter the formatter
39       */
40      public WriterTarget( final Writer   writer, final Formatter formatter )
41      {
42          super( formatter );
43  
44          if( null != writer )
45          {
46              setWriter( writer );
47              open();
48          }
49      }
50  
51      /**
52       * Set the writer.
53       * Close down writer and write tail if appropriate.
54       *
55       * @param writer the new writer
56       */
57      protected synchronized void setWriter( final Writer   writer )
58      {
59          if( null == writer )
60          {
61              throw new NullPointerException  ( "writer property must not be null" );
62          }
63  
64          m_output = writer;
65      }
66  
67      /**
68       * Concrete implementation of output that writes out to underlying writer.
69       *
70       * @param data the data to output
71       */
72      protected void write( final String   data )
73      {
74          try
75          {
76              m_output.write( data );
77              m_output.flush();
78          }
79          catch( final IOException   ioe )
80          {
81              getErrorHandler().error( "Caught an IOException", ioe, null );
82          }
83      }
84  
85      /**
86       * Shutdown target.
87       * Attempting to write to target after close() will cause errors to be logged.
88       */
89      public synchronized void close()
90      {
91          super.close();
92          shutdownWriter();
93      }
94  
95      /**
96       * Shutdown Writer.
97       */
98      protected synchronized void shutdownWriter()
99      {
100         final Writer   writer = m_output;
101         m_output = null;
102 
103         try
104         {
105             if( null != writer )
106             {
107                 writer.close();
108             }
109         }
110         catch( final IOException   ioe )
111         {
112             getErrorHandler().error( "Error closing Writer", ioe, null );
113         }
114     }
115 }
116
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