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DWR入门教程2 服务器端push技术

栏目:php教程时间:2015-03-23 08:05:59

前面1章讲授了DWR页面js代码如何直接调用后台服务器端java方法,今天这1章讲授如何在服务器端之间push数据到页面。

1。工程还沿用上1节的DwrDemo工程(不懂的可以先查看下上1章的内容)

首先需要修改web.xml文件

<?xml version="1.0" encoding="UTF⑻"?> <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"> <display-name></display-name> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list> <!-- 配置DWR --> <servlet> <servlet-name>dwr-invoker</servlet-name> <servlet-class>uk.ltd.getahead.dwr.DWRServlet</servlet-class> <init-param> <param-name>debug</param-name> <param-value>true</param-value> </init-param> <span style="color:#ff0000;"><!-- 开启DWR反向ajax功能 --> <init-param> <param-name>activeReverseAjaxEnabled</param-name> <param-value>true</param-value> </init-param></span> </servlet> <servlet-mapping> <servlet-name>dwr-invoker</servlet-name> <url-pattern>/dwr/*</url-pattern> </servlet-mapping> </web-app>
然后:

<%@ page language="java" import="java.util.*" pageEncoding="UTF⑻"%> <% String path = request.getContextPath(); String basePath = request.getScheme() + "://" + request.getServerName() + ":" + request.getServerPort() + path + "/"; %> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <base href="<%=basePath%>"> <title>Dwr Demo</title> <meta http-equiv="pragma" content="no-cache"> <meta http-equiv="cache-control" content="no-cache"> <meta http-equiv="expires" content="0"> <script type='text/javascript' src='/DwrDemo/dwr/engine.js'></script> <script type='text/javascript' src='/DwrDemo/dwr/util.js'></script> <script type='text/javascript' src='/DwrDemo/dwr/interface/DwrDemo.js'></script> <script type="text/javascript"> function dwrdemo() { //调用服务器段的DwrDemo类的getServerData方法,serverReturn是回调方法 DwrDemo.getServerData(serverReturn); } function serverReturn(data) { dwr.util.setValue("val", data); } function dwrdemo1() { DwrDemo.getPerson(serverReturn1); } function serverReturn1(data) { dwr.util.setValue("val1", data.name + ":" + data.age + ":" + data.address); } <span style="color:#ff0000;">//服务器端会调用这个js来向前真个输入框里面设置数据 function serverPush(data) { var v = dwr.util.getValue("box") ; dwr.util.setValue("box",v+data) ; }</span> </script> </head> <span style="color:#ff0000;"><!-- 需要在页面onload的时候设置反向ajax是true --> <body onload="dwr.engine.setActiveReverseAjax(true);"></span> <button name="btn" onclick="dwrdemo()" title="click me">click me</button> 返回值: <input type="text" id="val" name="val"> <button name="btn1" onclick="dwrdemo1()">取得用户</button> 用户信息: <input type="text" id="val1" name="val1"> <div> <input type="text" id="box" name="box"> </div> </body> </html>
最后修改java代码:

package cn.gov.zjport.dwr; import java.util.Collection; import org.directwebremoting.ScriptBuffer; import org.directwebremoting.ScriptSession; import org.directwebremoting.proxy.dwr.Util; import uk.ltd.getahead.dwr.WebContext; import uk.ltd.getahead.dwr.WebContextFactory; public class DwrDemo { public String getServerData() { serverPush(); return "Message from server"; } public Person getPerson() { Person person = new Person(); person.setName("张3"); person.setAge(32); person.setAddress("杭州下城区"); return person; } <span style="color:#ff0000;">/** * 开启1个线程用来定时的向前端来push数据 */ public void serverPush() { d dd = new d(getSessions()); dd.start(); } public Collection<ScriptSession> getSessions(){ WebContext content = WebContextFactory.get(); Collection<ScriptSession> session = content.getAllScriptSessions(); return session ; }</span> } class d extends Thread { private Collection<ScriptSession> sessions; public d(Collection<ScriptSession> sessions) { this.sessions = sessions; } @Override public void run() { int i = 1; while (true) { for (ScriptSession session : sessions) { push(i, session); } i++; try { Thread.sleep(2000); } catch (Exception ex) { ex.printStackTrace(); } } } <span style="color:#ff0000;">/** * 调用前端js方法:serverPush(data) * @param i * @param session */ public void push(int i, ScriptSession session) { ScriptBuffer buffer = new ScriptBuffer(); buffer.appendScript("serverPush("); buffer.appendData(i); buffer.appendScript(")"); Util util = new Util(session); util.addScript(buffer); System.out.println("----"); }</span> }
运行结果:

首先开启几个窗口然后点击其中1个串口的click me按钮会发现其他窗口的最后1个输入框也会出现数据:

第1幅图:



第2幅图:


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