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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.ThreadingBehavior;
33  import org.apache.http.annotation.Contract;
34  import org.apache.http.util.Args;
35  
36  /**
37   * Represents a protocol version. The "major.minor" numbering
38   * scheme is used to indicate versions of the protocol.
39   * <p>
40   * This class defines a protocol version as a combination of
41   * protocol name, major version number, and minor version number.
42   * Note that {@link #equals} and {@link #hashCode} are defined as
43   * final here, they cannot be overridden in derived classes.
44   * </p>
45   *
46   * @since 4.0
47   */
48  @Contract(threading = ThreadingBehavior.IMMUTABLE)
49  public class ProtocolVersion implements Serializable, Cloneable {
50  
51      private static final long serialVersionUID = 8950662842175091068L;
52  
53  
54      /** Name of the protocol. */
55      protected final String protocol;
56  
57      /** Major version number of the protocol */
58      protected final int major;
59  
60      /** Minor version number of the protocol */
61      protected final int minor;
62  
63  
64      /**
65       * Create a protocol version designator.
66       *
67       * @param protocol   the name of the protocol, for example "HTTP"
68       * @param major      the major version number of the protocol
69       * @param minor      the minor version number of the protocol
70       */
71      public ProtocolVersion(final String protocol, final int major, final int minor) {
72          this.protocol = Args.notNull(protocol, "Protocol name");
73          this.major = Args.notNegative(major, "Protocol minor version");
74          this.minor = Args.notNegative(minor, "Protocol minor version");
75      }
76  
77      /**
78       * Returns the name of the protocol.
79       *
80       * @return the protocol name
81       */
82      public final String getProtocol() {
83          return protocol;
84      }
85  
86      /**
87       * Returns the major version number of the protocol.
88       *
89       * @return the major version number.
90       */
91      public final int getMajor() {
92          return major;
93      }
94  
95      /**
96       * Returns the minor version number of the HTTP protocol.
97       *
98       * @return the minor version number.
99       */
100     public final int getMinor() {
101         return minor;
102     }
103 
104 
105     /**
106      * Obtains a specific version of this protocol.
107      * This can be used by derived classes to instantiate themselves instead
108      * of the base class, and to define constants for commonly used versions.
109      * <p>
110      * The default implementation in this class returns {@code this}
111      * if the version matches, and creates a new {@link ProtocolVersion}
112      * otherwise.
113      * </p>
114      *
115      * @param major     the major version
116      * @param minor     the minor version
117      *
118      * @return  a protocol version with the same protocol name
119      *          and the argument version
120      */
121     public ProtocolVersion forVersion(final int major, final int minor) {
122 
123         if ((major == this.major) && (minor == this.minor)) {
124             return this;
125         }
126 
127         // argument checking is done in the constructor
128         return new ProtocolVersion(this.protocol, major, minor);
129     }
130 
131 
132     /**
133      * Obtains a hash code consistent with {@link #equals}.
134      *
135      * @return  the hashcode of this protocol version
136      */
137     @Override
138     public final int hashCode() {
139         return this.protocol.hashCode() ^ (this.major * 100000) ^ this.minor;
140     }
141 
142 
143     /**
144      * Checks equality of this protocol version with an object.
145      * The object is equal if it is a protocl version with the same
146      * protocol name, major version number, and minor version number.
147      * The specific class of the object is <i>not</i> relevant,
148      * instances of derived classes with identical attributes are
149      * equal to instances of the base class and vice versa.
150      *
151      * @param obj       the object to compare with
152      *
153      * @return  {@code true} if the argument is the same protocol version,
154      *          {@code false} otherwise
155      */
156     @Override
157     public final boolean equals(final Object obj) {
158         if (this == obj) {
159             return true;
160         }
161         if (!(obj instanceof ProtocolVersion)) {
162             return false;
163         }
164         final ProtocolVersion that = (ProtocolVersion) obj;
165 
166         return ((this.protocol.equals(that.protocol)) &&
167                 (this.major == that.major) &&
168                 (this.minor == that.minor));
169     }
170 
171 
172     /**
173      * Checks whether this protocol can be compared to another one.
174      * Only protocol versions with the same protocol name can be
175      * {@link #compareToVersion compared}.
176      *
177      * @param that      the protocol version to consider
178      *
179      * @return  {@code true} if {@link #compareToVersion compareToVersion}
180      *          can be called with the argument, {@code false} otherwise
181      */
182     public boolean isComparable(final ProtocolVersion that) {
183         return (that != null) && this.protocol.equals(that.protocol);
184     }
185 
186 
187     /**
188      * Compares this protocol version with another one.
189      * Only protocol versions with the same protocol name can be compared.
190      * This method does <i>not</i> define a total ordering, as it would be
191      * required for {@link java.lang.Comparable}.
192      *
193      * @param that      the protocol version to compare with
194      *
195      * @return   a negative integer, zero, or a positive integer
196      *           as this version is less than, equal to, or greater than
197      *           the argument version.
198      *
199      * @throws IllegalArgumentException
200      *         if the argument has a different protocol name than this object,
201      *         or if the argument is {@code null}
202      */
203     public int compareToVersion(final ProtocolVersion that) {
204         Args.notNull(that, "Protocol version");
205         Args.check(this.protocol.equals(that.protocol),
206                 "Versions for different protocols cannot be compared: %s %s", this, that);
207         int delta = getMajor() - that.getMajor();
208         if (delta == 0) {
209             delta = getMinor() - that.getMinor();
210         }
211         return delta;
212     }
213 
214 
215     /**
216      * Tests if this protocol version is greater or equal to the given one.
217      *
218      * @param version   the version against which to check this version
219      *
220      * @return  {@code true} if this protocol version is
221      *          {@link #isComparable comparable} to the argument
222      *          and {@link #compareToVersion compares} as greater or equal,
223      *          {@code false} otherwise
224      */
225     public final boolean greaterEquals(final ProtocolVersion version) {
226         return isComparable(version) && (compareToVersion(version) >= 0);
227     }
228 
229 
230     /**
231      * Tests if this protocol version is less or equal to the given one.
232      *
233      * @param version   the version against which to check this version
234      *
235      * @return  {@code true} if this protocol version is
236      *          {@link #isComparable comparable} to the argument
237      *          and {@link #compareToVersion compares} as less or equal,
238      *          {@code false} otherwise
239      */
240     public final boolean lessEquals(final ProtocolVersion version) {
241         return isComparable(version) && (compareToVersion(version) <= 0);
242     }
243 
244 
245     /**
246      * Converts this protocol version to a string.
247      *
248      * @return  a protocol version string, like "HTTP/1.1"
249      */
250     @Override
251     public String toString() {
252         final StringBuilder buffer = new StringBuilder();
253         buffer.append(this.protocol);
254         buffer.append('/');
255         buffer.append(Integer.toString(this.major));
256         buffer.append('.');
257         buffer.append(Integer.toString(this.minor));
258         return buffer.toString();
259     }
260 
261     @Override
262     public Object clone() throws CloneNotSupportedException {
263         return super.clone();
264     }
265 
266 }