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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.annotation.NotThreadSafe;
34  import org.apache.http.io.SessionOutputBuffer;
35  import org.apache.http.util.Args;
36  
37  /**
38   * Output stream that writes data without any transformation. The end of
39   * the content entity is demarcated by closing the underlying connection
40   * (EOF condition). Entities transferred using this input stream can be of
41   * unlimited length.
42   * <p>
43   * Note that this class NEVER closes the underlying stream, even when close
44   * gets called.  Instead, the stream will be marked as closed and no further
45   * output will be permitted.
46   *
47   * @since 4.0
48   */
49  @NotThreadSafe
50  public class IdentityOutputStream extends OutputStream {
51  
52      /**
53       * Wrapped session output buffer.
54       */
55      private final SessionOutputBuffer out;
56  
57      /** True if the stream is closed. */
58      private boolean closed = false;
59  
60      public IdentityOutputStream(final SessionOutputBuffer out) {
61          super();
62          this.out = Args.notNull(out, "Session output buffer");
63      }
64  
65      /**
66       * <p>Does not close the underlying socket output.</p>
67       *
68       * @throws IOException If an I/O problem occurs.
69       */
70      @Override
71      public void close() throws IOException {
72          if (!this.closed) {
73              this.closed = true;
74              this.out.flush();
75          }
76      }
77  
78      @Override
79      public void flush() throws IOException {
80          this.out.flush();
81      }
82  
83      @Override
84      public void write(final byte[] b, final int off, final int len) throws IOException {
85          if (this.closed) {
86              throw new IOException("Attempted write to closed stream.");
87          }
88          this.out.write(b, off, len);
89      }
90  
91      @Override
92      public void write(final byte[] b) throws IOException {
93          write(b, 0, b.length);
94      }
95  
96      @Override
97      public void write(final int b) throws IOException {
98          if (this.closed) {
99              throw new IOException("Attempted write to closed stream.");
100         }
101         this.out.write(b);
102     }
103 
104 }