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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  package org.apache.commons.io.output;
18  
19  import java.io.IOException;
20  import java.io.OutputStream;
21  
22  /**
23   * Classic splitter of OutputStream. Named after the unix 'tee' 
24   * command. It allows a stream to be branched off so there 
25   * are now two streams.
26   *
27   */
28  public class TeeOutputStream extends ProxyOutputStream {
29  
30      /** the second OutputStream to write to */
31      protected OutputStream branch; //TODO consider making this private
32  
33      /**
34       * Constructs a TeeOutputStream.
35       * @param out the main OutputStream
36       * @param branch the second OutputStream
37       */
38      public TeeOutputStream(final OutputStream out, final OutputStream branch) {
39          super(out);
40          this.branch = branch;
41      }
42  
43      /**
44       * Write the bytes to both streams.
45       * @param b the bytes to write
46       * @throws IOException if an I/O error occurs
47       */
48      @Override
49      public synchronized void write(final byte[] b) throws IOException {
50          super.write(b);
51          this.branch.write(b);
52      }
53  
54      /**
55       * Write the specified bytes to both streams.
56       * @param b the bytes to write
57       * @param off The start offset
58       * @param len The number of bytes to write
59       * @throws IOException if an I/O error occurs
60       */
61      @Override
62      public synchronized void write(final byte[] b, final int off, final int len) throws IOException {
63          super.write(b, off, len);
64          this.branch.write(b, off, len);
65      }
66  
67      /**
68       * Write a byte to both streams.
69       * @param b the byte to write
70       * @throws IOException if an I/O error occurs
71       */
72      @Override
73      public synchronized void write(final int b) throws IOException {
74          super.write(b);
75          this.branch.write(b);
76      }
77  
78      /**
79       * Flushes both streams.
80       * @throws IOException if an I/O error occurs
81       */
82      @Override
83      public void flush() throws IOException {
84          super.flush();
85          this.branch.flush();
86      }
87  
88      /**
89       * Closes both output streams.
90       * 
91       * If closing the main output stream throws an exception, attempt to close the branch output stream.
92       * 
93       * If closing the main and branch output streams both throw exceptions, which exceptions is thrown by this method is
94       * currently unspecified and subject to change.
95       * 
96       * @throws IOException
97       *             if an I/O error occurs
98       */
99      @Override
100     public void close() throws IOException {
101         try {
102             super.close();
103         } finally {
104             this.branch.close();
105         }
106     }
107 
108 }