Tomcat comet 服务器推技术介绍
jopen
13年前
<p>Tomcat已经实现了自己的comet方式，并且提供了一个例子。这样网上的例子很多，我精简了些。</p> <p>MessageSender.java</p> <pre class="brush:java; toolbar: true; auto-links: false;">package me.comet; import java.io.IOException; import java.io.OutputStream; import java.util.Date; import javax.servlet.ServletResponse; public class MessageSender extends Thread { private ServletResponse connection; public MessageSender(ServletResponse connection) { this.connection = connection; } public void run() { try { while (true) { if (connection == null) { synchronized (this) { wait(); } } OutputStream out = connection.getOutputStream(); out.write(getString().getBytes()); out.flush(); connection.flushBuffer(); System.out.print(getString()); Thread.sleep(1000); } } catch (IOException e) { e.printStackTrace(); } catch (InterruptedException e) { e.printStackTrace(); } } @SuppressWarnings("deprecation") private String getString() { return Thread.currentThread()+" CurrentTime "+new Date().toLocaleString() + "\n"; } }</pre> <p></p> <p>TimeServlet.java</p> <pre class="brush:java; toolbar: true; auto-links: false;">package me.comet; import java.io.IOException; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.apache.catalina.CometEvent; import org.apache.catalina.CometProcessor; public class TimeServlet extends HttpServlet implements CometProcessor { private static final long serialVersionUID = 1L; private static final Integer TIMEOUT = 10 * 1000; private MessageSender sender = null; public void event(CometEvent event) throws IOException, ServletException { HttpServletRequest request = event.getHttpServletRequest(); HttpServletResponse response = event.getHttpServletResponse(); if (event.getEventType() == CometEvent.EventType.BEGIN) { log("Begin for session: " + request.getSession(true).getId()); request.setAttribute("org.apache.tomcat.comet.timeout", TIMEOUT); sender = new MessageSender(response); sender.start(); } else if (event.getEventType() == CometEvent.EventType.ERROR) { log("Error for session: " + request.getSession(true).getId()); event.close(); } else if (event.getEventType() == CometEvent.EventType.END) { log("End for session: " + request.getSession(true).getId()); event.close(); } else if (event.getEventType() == CometEvent.EventType.READ) { throw new UnsupportedOperationException("This servlet does not accept data"); } } @Override public void destroy() { sender.interrupt(); sender = null; } }</pre> <p>web.xml</p> <pre class="brush:java; toolbar: true; auto-links: false;"><?xml version="1.0" encoding="UTF-8"?> <web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list> <servlet> <servlet-name>TimeServlet</servlet-name> <servlet-class>me.comet.TimeServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>TimeServlet</servlet-name> <url-pattern>/time</url-pattern> </servlet-mapping> </web-app></pre> <p></p> <p>test.jsp</p> <pre class="brush:java; toolbar: true; auto-links: false;"><%@page contentType="text/html" pageEncoding="UTF-8"%> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>Comet Weather</title> </head> <body> <label>记录</label> <br/> <iframe src="http://localhost:8080/comet/time" width="60%" height="300" frameborder="1"></iframe> </body> </html></pre> <p></p> <p>更改 tomcat/conf/server.xml</p> <pre class="brush:java; toolbar: true; auto-links: false;"><Connector port="8080" protocol="org.apache.coyote.http11.Http11NioProtocol" connectionTimeout="20000" redirectPort="8443" /></pre> <p></p> <p>更改 tomcat/conf/context.xml</p> <pre class="brush:java; toolbar: true; auto-links: false;"><Context> <Loader delegate="true" /> <WatchedResource>WEB-INF/web.xml</WatchedResource> </Context></pre> <p></p> <p>jar包</p> <p>添加tomcat/lib/catalina.jar</p> <p></p> <p>测试地址：<a href="/misc/goto?guid=4959517915995783931">http://localhost:8080/comet/test.jsp</a> </p> 来自：http://zkeshun.iteye.com/blog/1391922