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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  
32  import org.apache.http.Header;
33  import org.apache.http.HeaderIterator;
34  import org.apache.http.HttpException;
35  import org.apache.http.HttpMessage;
36  import org.apache.http.annotation.NotThreadSafe;
37  import org.apache.http.io.HttpMessageWriter;
38  import org.apache.http.io.SessionOutputBuffer;
39  import org.apache.http.message.LineFormatter;
40  import org.apache.http.message.BasicLineFormatter;
41  import org.apache.http.params.HttpParams;
42  import org.apache.http.util.CharArrayBuffer;
43  
44  /**
45   * Abstract base class for HTTP message writers that serialize output to
46   * an instance of {@link SessionOutputBuffer}.
47   *
48   * @since 4.0
49   */
50  @NotThreadSafe
51  public abstract class AbstractMessageWriter<T extends HttpMessage> implements HttpMessageWriter<T> {
52  
53      protected final SessionOutputBuffer sessionBuffer;
54      protected final CharArrayBuffer lineBuf;
55      protected final LineFormatter lineFormatter;
56  
57      /**
58       * Creates an instance of AbstractMessageWriter.
59       *
60       * @param buffer the session output buffer.
61       * @param formatter the line formatter.
62       * @param params HTTP parameters.
63       */
64      public AbstractMessageWriter(final SessionOutputBuffer buffer,
65                                   final LineFormatter formatter,
66                                   final HttpParams params) {
67          super();
68          if (buffer == null) {
69              throw new IllegalArgumentException("Session input buffer may not be null");
70          }
71          this.sessionBuffer = buffer;
72          this.lineBuf = new CharArrayBuffer(128);
73          this.lineFormatter = (formatter != null) ?
74              formatter : BasicLineFormatter.DEFAULT;
75      }
76  
77      /**
78       * Subclasses must override this method to write out the first header line
79       * based on the {@link HttpMessage} passed as a parameter.
80       *
81       * @param message the message whose first line is to be written out.
82       * @throws IOException in case of an I/O error.
83       */
84      protected abstract void writeHeadLine(T message) throws IOException;
85  
86      public void write(final T message) throws IOException, HttpException {
87          if (message == null) {
88              throw new IllegalArgumentException("HTTP message may not be null");
89          }
90          writeHeadLine(message);
91          for (HeaderIterator it = message.headerIterator(); it.hasNext(); ) {
92              Header header = it.nextHeader();
93              this.sessionBuffer.writeLine
94                  (lineFormatter.formatHeader(this.lineBuf, header));
95          }
96          this.lineBuf.clear();
97          this.sessionBuffer.writeLine(this.lineBuf);
98      }
99  
100 }