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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;
29  
30  import java.io.Serializable;
31  
32  import org.apache.http.annotation.Immutable;
33  
34  /**
35   * Represents an HTTP version. HTTP uses a "major.minor" numbering
36   * scheme to indicate versions of the protocol.
37   * <p>
38   * The version of an HTTP message is indicated by an HTTP-Version field
39   * in the first line of the message.
40   * </p>
41   * <pre>
42   *     HTTP-Version   = "HTTP" "/" 1*DIGIT "." 1*DIGIT
43   * </pre>
44   *
45   * @since 4.0
46   */
47  @Immutable
48  public final class HttpVersion extends ProtocolVersion
49      implements Serializable {
50  
51      private static final long serialVersionUID = -5856653513894415344L;
52  
53      /** The protocol name. */
54      public static final String HTTP = "HTTP";
55  
56      /** HTTP protocol version 0.9 */
57      public static final HttpVersion HTTP_0_9 = new HttpVersion(0, 9);
58  
59      /** HTTP protocol version 1.0 */
60      public static final HttpVersion HTTP_1_0 = new HttpVersion(1, 0);
61  
62      /** HTTP protocol version 1.1 */
63      public static final HttpVersion HTTP_1_1 = new HttpVersion(1, 1);
64  
65  
66      /**
67       * Create an HTTP protocol version designator.
68       *
69       * @param major   the major version number of the HTTP protocol
70       * @param minor   the minor version number of the HTTP protocol
71       *
72       * @throws IllegalArgumentException if either major or minor version number is negative
73       */
74      public HttpVersion(int major, int minor) {
75          super(HTTP, major, minor);
76      }
77  
78  
79      /**
80       * Obtains a specific HTTP version.
81       *
82       * @param major     the major version
83       * @param minor     the minor version
84       *
85       * @return  an instance of {@link HttpVersion} with the argument version
86       */
87      @Override
88      public ProtocolVersion forVersion(int major, int minor) {
89  
90          if ((major == this.major) && (minor == this.minor)) {
91              return this;
92          }
93  
94          if (major == 1) {
95              if (minor == 0) {
96                  return HTTP_1_0;
97              }
98              if (minor == 1) {
99                  return HTTP_1_1;
100             }
101         }
102         if ((major == 0) && (minor == 9)) {
103             return HTTP_0_9;
104         }
105 
106         // argument checking is done in the constructor
107         return new HttpVersion(major, minor);
108     }
109 
110 }