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1   /*
2    * Copyright 2012 The Netty Project
3    *
4    * The Netty Project licenses this file to you under the Apache License,
5    * version 2.0 (the "License"); you may not use this file except in compliance
6    * with the License. You may obtain a copy of the License at:
7    *
8    *   http://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
12   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
13   * License for the specific language governing permissions and limitations
14   * under the License.
15   */
16  package io.netty.handler.codec.http;
17  
18  import io.netty.util.AsciiString;
19  
20  import static io.netty.util.internal.MathUtil.findNextPositivePowerOfTwo;
21  import static io.netty.util.internal.ObjectUtil.checkNotNull;
22  
23  /**
24   * The request method of HTTP or its derived protocols, such as
25   * <a href="http://en.wikipedia.org/wiki/Real_Time_Streaming_Protocol">RTSP</a> and
26   * <a href="http://en.wikipedia.org/wiki/Internet_Content_Adaptation_Protocol">ICAP</a>.
27   */
28  public class HttpMethod implements Comparable<HttpMethod> {
29      /**
30       * The OPTIONS method represents a request for information about the communication options
31       * available on the request/response chain identified by the Request-URI. This method allows
32       * the client to determine the options and/or requirements associated with a resource, or the
33       * capabilities of a server, without implying a resource action or initiating a resource
34       * retrieval.
35       */
36      public static final HttpMethod OPTIONS = new HttpMethod("OPTIONS");
37  
38      /**
39       * The GET method means retrieve whatever information (in the form of an entity) is identified
40       * by the Request-URI.  If the Request-URI refers to a data-producing process, it is the
41       * produced data which shall be returned as the entity in the response and not the source text
42       * of the process, unless that text happens to be the output of the process.
43       */
44      public static final HttpMethod GET = new HttpMethod("GET");
45  
46      /**
47       * The HEAD method is identical to GET except that the server MUST NOT return a message-body
48       * in the response.
49       */
50      public static final HttpMethod HEAD = new HttpMethod("HEAD");
51  
52      /**
53       * The POST method is used to request that the origin server accept the entity enclosed in the
54       * request as a new subordinate of the resource identified by the Request-URI in the
55       * Request-Line.
56       */
57      public static final HttpMethod POST = new HttpMethod("POST");
58  
59      /**
60       * The PUT method requests that the enclosed entity be stored under the supplied Request-URI.
61       */
62      public static final HttpMethod PUT = new HttpMethod("PUT");
63  
64      /**
65       * The PATCH method requests that a set of changes described in the
66       * request entity be applied to the resource identified by the Request-URI.
67       */
68      public static final HttpMethod PATCH = new HttpMethod("PATCH");
69  
70      /**
71       * The DELETE method requests that the origin server delete the resource identified by the
72       * Request-URI.
73       */
74      public static final HttpMethod DELETE = new HttpMethod("DELETE");
75  
76      /**
77       * The TRACE method is used to invoke a remote, application-layer loop- back of the request
78       * message.
79       */
80      public static final HttpMethod TRACE = new HttpMethod("TRACE");
81  
82      /**
83       * This specification reserves the method name CONNECT for use with a proxy that can dynamically
84       * switch to being a tunnel
85       */
86      public static final HttpMethod CONNECT = new HttpMethod("CONNECT");
87  
88      private static final EnumNameMap<HttpMethod> methodMap;
89  
90      static {
91          methodMap = new EnumNameMap<HttpMethod>(
92                  new EnumNameMap.Node<HttpMethod>(OPTIONS.toString(), OPTIONS),
93                  new EnumNameMap.Node<HttpMethod>(GET.toString(), GET),
94                  new EnumNameMap.Node<HttpMethod>(HEAD.toString(), HEAD),
95                  new EnumNameMap.Node<HttpMethod>(POST.toString(), POST),
96                  new EnumNameMap.Node<HttpMethod>(PUT.toString(), PUT),
97                  new EnumNameMap.Node<HttpMethod>(PATCH.toString(), PATCH),
98                  new EnumNameMap.Node<HttpMethod>(DELETE.toString(), DELETE),
99                  new EnumNameMap.Node<HttpMethod>(TRACE.toString(), TRACE),
100                 new EnumNameMap.Node<HttpMethod>(CONNECT.toString(), CONNECT));
101     }
102 
103     /**
104      * Returns the {@link HttpMethod} represented by the specified name.
105      * If the specified name is a standard HTTP method name, a cached instance
106      * will be returned.  Otherwise, a new instance will be returned.
107      */
108     public static HttpMethod valueOf(String name) {
109         HttpMethod result = methodMap.get(name);
110         return result != null ? result : new HttpMethod(name);
111     }
112 
113     private final AsciiString name;
114 
115     /**
116      * Creates a new HTTP method with the specified name.  You will not need to
117      * create a new method unless you are implementing a protocol derived from
118      * HTTP, such as
119      * <a href="http://en.wikipedia.org/wiki/Real_Time_Streaming_Protocol">RTSP</a> and
120      * <a href="http://en.wikipedia.org/wiki/Internet_Content_Adaptation_Protocol">ICAP</a>
121      */
122     public HttpMethod(String name) {
123         name = checkNotNull(name, "name").trim();
124         if (name.isEmpty()) {
125             throw new IllegalArgumentException("empty name");
126         }
127 
128         for (int i = 0; i < name.length(); i ++) {
129             char c = name.charAt(i);
130             if (Character.isISOControl(c) || Character.isWhitespace(c)) {
131                 throw new IllegalArgumentException("invalid character in name");
132             }
133         }
134 
135         this.name = AsciiString.cached(name);
136     }
137 
138     /**
139      * Returns the name of this method.
140      */
141     public String name() {
142         return name.toString();
143     }
144 
145     /**
146      * Returns the name of this method.
147      */
148     public AsciiString asciiName() {
149         return name;
150     }
151 
152     @Override
153     public int hashCode() {
154         return name().hashCode();
155     }
156 
157     @Override
158     public boolean equals(Object o) {
159         if (!(o instanceof HttpMethod)) {
160             return false;
161         }
162 
163         HttpMethod that = (HttpMethod) o;
164         return name().equals(that.name());
165     }
166 
167     @Override
168     public String toString() {
169         return name.toString();
170     }
171 
172     @Override
173     public int compareTo(HttpMethod o) {
174         return name().compareTo(o.name());
175     }
176 
177     private static final class EnumNameMap<T> {
178         private final EnumNameMap.Node<T>[] values;
179         private final int valuesMask;
180 
181         EnumNameMap(EnumNameMap.Node<T>... nodes) {
182             values = (EnumNameMap.Node<T>[]) new EnumNameMap.Node[findNextPositivePowerOfTwo(nodes.length)];
183             valuesMask = values.length - 1;
184             for (EnumNameMap.Node<T> node : nodes) {
185                 int i = hashCode(node.key) & valuesMask;
186                 if (values[i] != null) {
187                     throw new IllegalArgumentException("index " + i + " collision between values: [" +
188                             values[i].key + ", " + node.key + ']');
189                 }
190                 values[i] = node;
191             }
192         }
193 
194         T get(String name) {
195             EnumNameMap.Node<T> node = values[hashCode(name) & valuesMask];
196             return node == null || !node.key.equals(name) ? null : node.value;
197         }
198 
199         private static int hashCode(String name) {
200             // This hash code needs to produce a unique index in the "values" array for each HttpMethod. If new
201             // HttpMethods are added this algorithm will need to be adjusted. The constructor will "fail fast" if there
202             // are duplicates detected.
203             // For example with the current set of HttpMethods it just so happens that the String hash code value
204             // shifted right by 6 bits modulo 16 is unique relative to all other HttpMethod values.
205             return name.hashCode() >>> 6;
206         }
207 
208         private static final class Node<T> {
209             final String key;
210             final T value;
211 
212             Node(String key, T value) {
213                 this.key = key;
214                 this.value = value;
215             }
216         }
217     }
218 }