Java tutorial
/* * Copyright 2012 The Netty Project * * The Netty Project licenses this file to you under the Apache License, * version 2.0 (the "License"); you may not use this file except in compliance * with the License. You may obtain a copy of the License at: * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the * License for the specific language governing permissions and limitations * under the License. */ package io.netty.handler.codec.http; import io.netty.util.AsciiString; import static io.netty.util.internal.MathUtil.findNextPositivePowerOfTwo; import static io.netty.util.internal.ObjectUtil.checkNotNull; /** * The request method of HTTP or its derived protocols, such as * <a href="http://en.wikipedia.org/wiki/Real_Time_Streaming_Protocol">RTSP</a> and * <a href="http://en.wikipedia.org/wiki/Internet_Content_Adaptation_Protocol">ICAP</a>. */ public class HttpMethod implements Comparable<HttpMethod> { /** * The OPTIONS method represents a request for information about the communication options * available on the request/response chain identified by the Request-URI. This method allows * the client to determine the options and/or requirements associated with a resource, or the * capabilities of a server, without implying a resource action or initiating a resource * retrieval. */ public static final HttpMethod OPTIONS = new HttpMethod("OPTIONS"); /** * The GET method means retrieve whatever information (in the form of an entity) is identified * by the Request-URI. If the Request-URI refers to a data-producing process, it is the * produced data which shall be returned as the entity in the response and not the source text * of the process, unless that text happens to be the output of the process. */ public static final HttpMethod GET = new HttpMethod("GET"); /** * The HEAD method is identical to GET except that the server MUST NOT return a message-body * in the response. */ public static final HttpMethod HEAD = new HttpMethod("HEAD"); /** * The POST method is used to request that the origin server accept the entity enclosed in the * request as a new subordinate of the resource identified by the Request-URI in the * Request-Line. */ public static final HttpMethod POST = new HttpMethod("POST"); /** * The PUT method requests that the enclosed entity be stored under the supplied Request-URI. */ public static final HttpMethod PUT = new HttpMethod("PUT"); /** * The PATCH method requests that a set of changes described in the * request entity be applied to the resource identified by the Request-URI. */ public static final HttpMethod PATCH = new HttpMethod("PATCH"); /** * The DELETE method requests that the origin server delete the resource identified by the * Request-URI. */ public static final HttpMethod DELETE = new HttpMethod("DELETE"); /** * The TRACE method is used to invoke a remote, application-layer loop- back of the request * message. */ public static final HttpMethod TRACE = new HttpMethod("TRACE"); /** * This specification reserves the method name CONNECT for use with a proxy that can dynamically * switch to being a tunnel */ public static final HttpMethod CONNECT = new HttpMethod("CONNECT"); private static final EnumNameMap<HttpMethod> methodMap; static { methodMap = new EnumNameMap<HttpMethod>(new EnumNameMap.Node<HttpMethod>(OPTIONS.toString(), OPTIONS), new EnumNameMap.Node<HttpMethod>(GET.toString(), GET), new EnumNameMap.Node<HttpMethod>(HEAD.toString(), HEAD), new EnumNameMap.Node<HttpMethod>(POST.toString(), POST), new EnumNameMap.Node<HttpMethod>(PUT.toString(), PUT), new EnumNameMap.Node<HttpMethod>(PATCH.toString(), PATCH), new EnumNameMap.Node<HttpMethod>(DELETE.toString(), DELETE), new EnumNameMap.Node<HttpMethod>(TRACE.toString(), TRACE), new EnumNameMap.Node<HttpMethod>(CONNECT.toString(), CONNECT)); } /** * Returns the {@link HttpMethod} represented by the specified name. * If the specified name is a standard HTTP method name, a cached instance * will be returned. Otherwise, a new instance will be returned. */ public static HttpMethod valueOf(String name) { HttpMethod result = methodMap.get(name); return result != null ? result : new HttpMethod(name); } private final AsciiString name; /** * Creates a new HTTP method with the specified name. You will not need to * create a new method unless you are implementing a protocol derived from * HTTP, such as * <a href="http://en.wikipedia.org/wiki/Real_Time_Streaming_Protocol">RTSP</a> and * <a href="http://en.wikipedia.org/wiki/Internet_Content_Adaptation_Protocol">ICAP</a> */ public HttpMethod(String name) { name = checkNotNull(name, "name").trim(); if (name.isEmpty()) { throw new IllegalArgumentException("empty name"); } for (int i = 0; i < name.length(); i++) { char c = name.charAt(i); if (Character.isISOControl(c) || Character.isWhitespace(c)) { throw new IllegalArgumentException("invalid character in name"); } } this.name = AsciiString.cached(name); } /** * Returns the name of this method. */ public String name() { return name.toString(); } /** * Returns the name of this method. */ public AsciiString asciiName() { return name; } @Override public int hashCode() { return name().hashCode(); } @Override public boolean equals(Object o) { if (this == o) { return true; } if (!(o instanceof HttpMethod)) { return false; } HttpMethod that = (HttpMethod) o; return name().equals(that.name()); } @Override public String toString() { return name.toString(); } @Override public int compareTo(HttpMethod o) { if (o == this) { return 0; } return name().compareTo(o.name()); } private static final class EnumNameMap<T> { private final EnumNameMap.Node<T>[] values; private final int valuesMask; EnumNameMap(EnumNameMap.Node<T>... nodes) { values = (EnumNameMap.Node<T>[]) new EnumNameMap.Node[findNextPositivePowerOfTwo(nodes.length)]; valuesMask = values.length - 1; for (EnumNameMap.Node<T> node : nodes) { int i = hashCode(node.key) & valuesMask; if (values[i] != null) { throw new IllegalArgumentException( "index " + i + " collision between values: [" + values[i].key + ", " + node.key + ']'); } values[i] = node; } } T get(String name) { EnumNameMap.Node<T> node = values[hashCode(name) & valuesMask]; return node == null || !node.key.equals(name) ? null : node.value; } private static int hashCode(String name) { // This hash code needs to produce a unique index in the "values" array for each HttpMethod. If new // HttpMethods are added this algorithm will need to be adjusted. The constructor will "fail fast" if there // are duplicates detected. // For example with the current set of HttpMethods it just so happens that the String hash code value // shifted right by 6 bits modulo 16 is unique relative to all other HttpMethod values. return name.hashCode() >>> 6; } private static final class Node<T> { final String key; final T value; Node(String key, T value) { this.key = key; this.value = value; } } } }