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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.entity;
29  
30  import java.io.IOException;
31  import java.io.OutputStream;
32  
33  import org.apache.http.HttpEntity;
34  import org.apache.http.HttpException;
35  import org.apache.http.HttpMessage;
36  import org.apache.http.annotation.Immutable;
37  import org.apache.http.entity.ContentLengthStrategy;
38  import org.apache.http.impl.io.ChunkedOutputStream;
39  import org.apache.http.impl.io.ContentLengthOutputStream;
40  import org.apache.http.impl.io.IdentityOutputStream;
41  import org.apache.http.io.SessionOutputBuffer;
42  
43  /**
44   * HTTP entity serializer.
45   * <p>
46   * This entity serializer currently supports "chunked" and "identitiy"
47   * transfer-coding and content length delimited content.
48   * <p>
49   * This class relies on a specific implementation of
50   * {@link ContentLengthStrategy} to determine the content length or transfer
51   * encoding of the entity.
52   * <p>
53   * This class writes out the content of {@link HttpEntity} to the data stream
54   * using a transfer coding based on properties on the HTTP message.
55   *
56   * @since 4.0
57   */
58  @Immutable // assuming injected dependencies are immutable
59  public class EntitySerializer {
60  
61      private final ContentLengthStrategy lenStrategy;
62  
63      public EntitySerializer(final ContentLengthStrategy lenStrategy) {
64          super();
65          if (lenStrategy == null) {
66              throw new IllegalArgumentException("Content length strategy may not be null");
67          }
68          this.lenStrategy = lenStrategy;
69      }
70  
71      /**
72       * Creates a transfer codec based on properties of the given HTTP message
73       * and returns {@link OutputStream} instance that transparently encodes
74       * output data as it is being written out to the output stream.
75       * <p>
76       * This method is called by the public
77       * {@link #serialize(SessionOutputBuffer, HttpMessage, HttpEntity)}.
78       *
79       * @param outbuffer the session output buffer.
80       * @param message the HTTP message.
81       * @return output stream.
82       * @throws HttpException in case of HTTP protocol violation.
83       * @throws IOException in case of an I/O error.
84       */
85      protected OutputStream doSerialize(
86              final SessionOutputBuffer outbuffer,
87              final HttpMessage message) throws HttpException, IOException {
88          long len = this.lenStrategy.determineLength(message);
89          if (len == ContentLengthStrategy.CHUNKED) {
90              return new ChunkedOutputStream(outbuffer);
91          } else if (len == ContentLengthStrategy.IDENTITY) {
92              return new IdentityOutputStream(outbuffer);
93          } else {
94              return new ContentLengthOutputStream(outbuffer, len);
95          }
96      }
97  
98      /**
99       * Writes out the content of the given HTTP entity to the session output
100      * buffer based on properties of the given HTTP message.
101      *
102      * @param outbuffer the output session buffer.
103      * @param message the HTTP message.
104      * @param entity the HTTP entity to be written out.
105      * @throws HttpException in case of HTTP protocol violation.
106      * @throws IOException in case of an I/O error.
107      */
108     public void serialize(
109             final SessionOutputBuffer outbuffer,
110             final HttpMessage message,
111             final HttpEntity entity) throws HttpException, IOException {
112         if (outbuffer == null) {
113             throw new IllegalArgumentException("Session output buffer may not be null");
114         }
115         if (message == null) {
116             throw new IllegalArgumentException("HTTP message may not be null");
117         }
118         if (entity == null) {
119             throw new IllegalArgumentException("HTTP entity may not be null");
120         }
121         OutputStream outstream = doSerialize(outbuffer, message);
122         entity.writeTo(outstream);
123         outstream.close();
124     }
125 
126 }