View Javadoc

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 cuts off after a defined number of bytes. This class
38   * is used to send content of HTTP messages where the end of the content entity
39   * is determined by the value of the <code>Content-Length header</code>.
40   * Entities transferred using this stream can be maximum {@link Long#MAX_VALUE}
41   * long.
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 ContentLengthOutputStream extends OutputStream {
51  
52      /**
53       * Wrapped session output buffer.
54       */
55      private final SessionOutputBuffer out;
56  
57      /**
58       * The maximum number of bytes that can be written the stream. Subsequent
59       * write operations will be ignored.
60       */
61      private final long contentLength;
62  
63      /** Total bytes written */
64      private long total = 0;
65  
66      /** True if the stream is closed. */
67      private boolean closed = false;
68  
69      /**
70       * Wraps a session output buffer and cuts off output after a defined number
71       * of bytes.
72       *
73       * @param out The session output buffer
74       * @param contentLength The maximum number of bytes that can be written to
75       * the stream. Subsequent write operations will be ignored.
76       *
77       * @since 4.0
78       */
79      public ContentLengthOutputStream(final SessionOutputBuffer out, long contentLength) {
80          super();
81          if (out == null) {
82              throw new IllegalArgumentException("Session output buffer may not be null");
83          }
84          if (contentLength < 0) {
85              throw new IllegalArgumentException("Content length may not be negative");
86          }
87          this.out = out;
88          this.contentLength = contentLength;
89      }
90  
91      /**
92       * <p>Does not close the underlying socket output.</p>
93       *
94       * @throws IOException If an I/O problem occurs.
95       */
96      @Override
97      public void close() throws IOException {
98          if (!this.closed) {
99              this.closed = true;
100             this.out.flush();
101         }
102     }
103 
104     @Override
105     public void flush() throws IOException {
106         this.out.flush();
107     }
108 
109     @Override
110     public void write(byte[] b, int off, int len) throws IOException {
111         if (this.closed) {
112             throw new IOException("Attempted write to closed stream.");
113         }
114         if (this.total < this.contentLength) {
115             long max = this.contentLength - this.total;
116             if (len > max) {
117                 len = (int) max;
118             }
119             this.out.write(b, off, len);
120             this.total += len;
121         }
122     }
123 
124     @Override
125     public void write(byte[] b) throws IOException {
126         write(b, 0, b.length);
127     }
128 
129     @Override
130     public void write(int b) throws IOException {
131         if (this.closed) {
132             throw new IOException("Attempted write to closed stream.");
133         }
134         if (this.total < this.contentLength) {
135             this.out.write(b);
136             this.total++;
137         }
138     }
139 
140 }