基于Tomcat的WebSocket(5月8日更新)

来源：互联网发布：下载不了软件怎么办编辑：程序博客网时间：2024/05/09 09:26

2014年2月更新: 此API为Tomcat私有,当时Java没有标准API,现在Java有标准API,JSR536,此API不建议使用,新的用法请参照: http://redstarofsleep.iteye.com/blog/1974620

之前大概的看过WebSocket,当时Tomcat还不支持WebSocket,所以当时写了一篇基于Jetty的WebSocket实现,地址如下:

http://redstarofsleep.iteye.com/blog/1307608

现在Tomcat7.0.27发布了，从这个版本开始Tomcat就支持WebSocket了。

Tomcat的WebSocket和Jetty的大致上差不多，大同小异，这里就简单的贴两个类吧（此例子未考虑多线程的情况）：

第一个类，这个和Jetty一样，需要一个Servlet来处理WebSocket请求：

package lhc.websocket;import org.apache.catalina.websocket.StreamInbound;import org.apache.catalina.websocket.WebSocketServlet;public class MyWebSocketServlet extends WebSocketServlet {private static final long serialVersionUID = -7178893327801338294L;@Overrideprotected StreamInbound createWebSocketInbound(String arg0) {System.out.println("##########");return new MyMessageInbound();}}

这个Servlet继承自WebSocketServlet，实现createWebSocketInbound方法。该方法返回第二个类的实例。

第二个类，处理每一次具体的WebSocket任务：

package lhc.websocket;import java.io.IOException;import java.nio.ByteBuffer;import java.nio.CharBuffer;import lhc.init.InitServlet;import org.apache.catalina.websocket.MessageInbound;import org.apache.catalina.websocket.WsOutbound;public class MyMessageInbound extends MessageInbound {@Overrideprotected void onBinaryMessage(ByteBuffer arg0) throws IOException {// TODO Auto-generated method stub}@Overrideprotected void onTextMessage(CharBuffer msg) throws IOException {for (MessageInbound messageInbound : InitServlet.getSocketList()) {CharBuffer buffer = CharBuffer.wrap(msg);WsOutbound outbound = messageInbound.getWsOutbound();outbound.writeTextMessage(buffer);outbound.flush();}}@Overrideprotected void onClose(int status) {InitServlet.getSocketList().remove(this);super.onClose(status);}@Overrideprotected void onOpen(WsOutbound outbound) {super.onOpen(outbound);InitServlet.getSocketList().add(this);}}

这个类继承自MessageInbound类，必须实现onBinaryMessage和onTextMessage方法。Jetty中只有一个onMessage方法，而Tomcat细化成了2个方法。

还要一个初始化的Servlet

package lhc.init;import java.util.ArrayList;import java.util.List;import javax.servlet.ServletConfig;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import org.apache.catalina.websocket.MessageInbound;public class InitServlet extends HttpServlet {private static final long serialVersionUID = -3163557381361759907L;private static List<MessageInbound> socketList;          public void init(ServletConfig config) throws ServletException {          InitServlet.socketList = new ArrayList<MessageInbound>();          super.init(config);          System.out.println("Server start============");      }            public static List<MessageInbound> getSocketList() {          return InitServlet.socketList;      }  }

最后，web.xml中进行一下Servlet的配置。

<?xml version="1.0" encoding="UTF-8"?><web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">  <display-name>wsoc</display-name>  <welcome-file-list>    <welcome-file>index.jsp</welcome-file>  </welcome-file-list>    <servlet>  <servlet-name>mywebsocket</servlet-name>  <servlet-class>lhc.websocket.MyWebSocketServlet</servlet-class>  </servlet>  <servlet-mapping>  <servlet-name>mywebsocket</servlet-name>  <url-pattern>*.do</url-pattern>  </servlet-mapping>    <servlet>  <servlet-name>initServlet</servlet-name>  <servlet-class>lhc.init.InitServlet</servlet-class>  <load-on-startup>1</load-on-startup>  </servlet></web-app>

页面的话，就是标准的HTML5的websocket，这个和服务器是否是Tomcat或者Jetty是无关的：

<%@ page language="java" contentType="text/html; charset=UTF-8"    pageEncoding="UTF-8"%><!DOCTYPE html><html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>Index</title><script type="text/javascript">var ws = null;function startWebSocket() {if ('WebSocket' in window)ws = new WebSocket("ws://localhost:8080/wsoc/mywebsocket.do");else if ('MozWebSocket' in window)ws = new MozWebSocket("ws://localhost:8080/wsoc/mywebsocket.do");elsealert("not support");ws.onmessage = function(evt) {alert(evt.data);};ws.onclose = function(evt) {alert("close");};ws.onopen = function(evt) {alert("open");};}function sendMsg() {ws.send(document.getElementById('writeMsg').value);}</script></head><body onload="startWebSocket();"><input type="text" id="writeMsg"></input><input type="button" value="send" onclick="sendMsg()"></input></body></html>

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