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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  
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  @NotThreadSafe
49  public class IdentityOutputStream extends OutputStream {
50  
51      /**
52       * Wrapped session output buffer.
53       */
54      private final SessionOutputBuffer out;
55  
56      /** True if the stream is closed. */
57      private boolean closed = false;
58  
59      public IdentityOutputStream(final SessionOutputBuffer out) {
60          super();
61          if (out == null) {
62              throw new IllegalArgumentException("Session output buffer may not be null");
63          }
64          this.out = out;
65      }
66  
67      /**
68       * <p>Does not close the underlying socket output.</p>
69       *
70       * @throws IOException If an I/O problem occurs.
71       */
72      @Override
73      public void close() throws IOException {
74          if (!this.closed) {
75              this.closed = true;
76              this.out.flush();
77          }
78      }
79  
80      @Override
81      public void flush() throws IOException {
82          this.out.flush();
83      }
84  
85      @Override
86      public void write(byte[] b, int off, int len) throws IOException {
87          if (this.closed) {
88              throw new IOException("Attempted write to closed stream.");
89          }
90          this.out.write(b, off, len);
91      }
92  
93      @Override
94      public void write(byte[] b) throws IOException {
95          write(b, 0, b.length);
96      }
97  
98      @Override
99      public void write(int b) throws IOException {
100         if (this.closed) {
101             throw new IOException("Attempted write to closed stream.");
102         }
103         this.out.write(b);
104     }
105 
106 }