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1   /*
2    * ====================================================================
3    * Licensed to the Apache Software Foundation (ASF) under one
4    * or more contributor license agreements.  See the NOTICE file
5    * distributed with this work for additional information
6    * regarding copyright ownership.  The ASF licenses this file
7    * to you under the Apache License, Version 2.0 (the
8    * "License"); you may not use this file except in compliance
9    * with the License.  You may obtain a copy of the License at
10   *
11   *   http://www.apache.org/licenses/LICENSE-2.0
12   *
13   * Unless required by applicable law or agreed to in writing,
14   * software distributed under the License is distributed on an
15   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
16   * KIND, either express or implied.  See the License for the
17   * specific language governing permissions and limitations
18   * under the License.
19   * ====================================================================
20   *
21   * This software consists of voluntary contributions made by many
22   * individuals on behalf of the Apache Software Foundation.  For more
23   * information on the Apache Software Foundation, please see
24   * <http://www.apache.org/>.
25   *
26   */
27  
28  package org.apache.http.impl.io;
29  
30  import java.io.IOException;
31  import java.io.OutputStream;
32  
33  import org.apache.http.io.SessionOutputBuffer;
34  import org.apache.http.util.Args;
35  
36  /**
37   * Output stream that writes data without any transformation. The end of
38   * the content entity is demarcated by closing the underlying connection
39   * (EOF condition). Entities transferred using this input stream can be of
40   * unlimited length.
41   * <p>
42   * Note that this class NEVER closes the underlying stream, even when close
43   * gets called.  Instead, the stream will be marked as closed and no further
44   * output will be permitted.
45   *
46   * @since 4.0
47   */
48  public class IdentityOutputStream extends OutputStream {
49  
50      /**
51       * Wrapped session output buffer.
52       */
53      private final SessionOutputBuffer out;
54  
55      /** True if the stream is closed. */
56      private boolean closed = false;
57  
58      public IdentityOutputStream(final SessionOutputBuffer out) {
59          super();
60          this.out = Args.notNull(out, "Session output buffer");
61      }
62  
63      /**
64       * <p>Does not close the underlying socket output.</p>
65       *
66       * @throws IOException If an I/O problem occurs.
67       */
68      @Override
69      public void close() throws IOException {
70          if (!this.closed) {
71              this.closed = true;
72              this.out.flush();
73          }
74      }
75  
76      @Override
77      public void flush() throws IOException {
78          this.out.flush();
79      }
80  
81      @Override
82      public void write(final byte[] b, final int off, final int len) throws IOException {
83          if (this.closed) {
84              throw new IOException("Attempted write to closed stream.");
85          }
86          this.out.write(b, off, len);
87      }
88  
89      @Override
90      public void write(final byte[] b) throws IOException {
91          write(b, 0, b.length);
92      }
93  
94      @Override
95      public void write(final int b) throws IOException {
96          if (this.closed) {
97              throw new IOException("Attempted write to closed stream.");
98          }
99          this.out.write(b);
100     }
101 
102 }