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关于DWR怎么使用我的上一篇博文里面记录了，这里写一个DWR一对一消息推送的WEB程序，也就是WEB一对一聊天。我的思路是这样的：首先每个用户在登陆后在各自的页面放置一个唯一标记（如用户的ID，也可以放在session里面），用户A向用户B发送的消息 --》服务器 --》JAVA方法--》JAVA方法调用前端所有正在访问聊天页面的JS函数--》JS判断消息发送至的客户端是否是用户B --》是则显示，否则不显示；用户B向A同样过程
首先是该项目的web.xml文件：
<?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" 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>DWRDemo</display-name> <!-- 加入DWRServlet --> <servlet> <servlet-name>dwr-invoker</servlet-name> <servlet-class>org.directwebremoting.servlet.DwrServlet</servlet-class> <init-param> <param-name>debug</param-name> <param-value>true</param-value> </init-param> <!-- 使用comet方式 --> <init-param> <param-name>activeReverseAjaxEnabled</param-name> <param-value>true</param-value> </init-param> </servlet> <servlet-mapping> <servlet-name>dwr-invoker</servlet-name> <url-pattern>/dwr/*</url-pattern> </servlet-mapping> <welcome-file-list> <welcome-file>index.html</welcome-file> <welcome-file>index.htm</welcome-file> <welcome-file>index.jsp</welcome-file> <welcome-file>default.html</welcome-file> <welcome-file>default.htm</welcome-file> <welcome-file>default.jsp</welcome-file> </welcome-file-list> </web-app>
然后是index.jsp，这是主页面：
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
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">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
<!-- <script src="http://libs.baidu.com/jquery/2.0.0/jquery.js"></script> -->
<script type=‘text/javascript‘ src=‘<%=basePath%>dwr/engine.js‘></script>
<script type=‘text/javascript‘ src=‘<%=basePath%>dwr/util.js‘></script>
<script type=‘text/javascript‘ src=‘<%=basePath%>dwr/interface/Hello.js‘></script>
<script type=‘text/javascript‘
src=‘<%=basePath%>dwr/interface/LoginService.js‘></script>
<script type=‘text/javascript‘
src=‘<%=basePath%>dwr/interface/MessageService.js‘></script>
<script type="text/javascript">
dwr.engine.setActiveReverseAjax(true);//使用长链接的方式
/**
* 模拟用户登陆
*/
function login() {
var inputName = dwr.util.getValue("userName");
//alert(inputName);
if (inputName.length == 0) {
alert("please enter your user name");
} else {
LoginService.login(inputName, function(data) {
dwr.util.setValue("loginName", data);
});
}
}
/**
* 本用户发送信息到服务端JAVA类
*/
function sendMessage() {
var inputMessageText = dwr.util.getValue("messageText");
var userName = dwr.util.getValue("loginName");
var toName = dwr.util.getValue("toName");
if (userName.length == 0) {
alert("please login");
} else if (toName.length == 0) {
alert("please enter the name you send to");
} else if (inputMessageText.length == 0) {
alert("please enter the message you want to send");
} else {
var mydate = new Date();
var currentDate = mydate.toLocaleTimeString();
/**
* 发送消息至服务其，toName是发送到哪个用户的用户标识
*/
MessageService.sendMessage(currentDate + " " + " " + userName
+ " : " + inputMessageText, toName);
sendMessageToChatArea();//本用户发送的消息更新对话域
}
}
/**
* 本用户发送完成，对方信息域显示更新
* @param message
* @param toName
* @returns
*/
function newMessage(message, toName) {
var thisUserName = dwr.util.getValue("loginName");
if (toName == thisUserName) {
var chatArea = document.getElementById("chatArea");
var oldMessage = chatArea.innerHTML;
if (oldMessage.length == 0) {
chatArea.innerHTML = message;
} else {
chatArea.innerHTML = oldMessage + "<br/>" + message;
//始终显示最新发送的消息
var chatAreaHeight = chatArea.scrollHeight;
chatArea.scrollTop = chatAreaHeight;
}
}
}
/**
* 本用户发送信息显示在信息域
* @returns
*/
function sendMessageToChatArea() {
var inputMessageText = dwr.util.getValue("messageText");
var chatArea = document.getElementById("chatArea");
var oldMessage = chatArea.innerHTML;
var mydate = new Date();
var currentDate = mydate.toLocaleTimeString();
var loginName = dwr.util.getValue("loginName");
chatArea.innerHTML = oldMessage + "<br/>" + currentDate + " "
+ loginName + " : " + inputMessageText;
//始终显示最新发送的消息
var chatAreaHeight = chatArea.scrollHeight;
chatArea.scrollTop = chatAreaHeight;
}
</script>
</head>
<body>
<h1>Simple Test</h1>
<p>
Name: <input type="text" id="demoName" /> <input value="Send"
type="button" onclick="update()" /> <br /> Reply: <span
id="demoReply"></span>
</p>
<hr />
<h1>DWR ANDJAVA Chat Test</h1>
<span id="loginName"></span>
<br /> Your Name
<input type="text" size="30" id="userName">
<input type="button" value="login" onclick="login()" />
<br /> Send To Who
<input type="text" size="30" id="toName" />
<br />
<div id="chatArea" style="width: 600px; height: 300px; overflow: auto"></div>
<br />
<p>
<input type="text" size="40" id="messageText" /> | <input
type="button" value="Send" onclick="sendMessage()">
</p>
</body>
</html>
dwr.xml文件：
<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE dwr PUBLIC "-//GetAhead Limited//DTD Direct Web Remoting 3.0//EN" "http://getahead.org/dwr/dwr30.dtd"> <dwr> <allow> <create creator="new" javascript="MessageService"> <param name="class" value="com.dwrdemo.pojo.MessageService"></param> </create> <create creator="new" javascript="LoginService"> <param name="class" value="com.dwrdemo.pojo.LoginService"></param> </create> </allow> </dwr>
JAVA代码：
LoginService:
package com.dwrdemo.pojo;
/**
* ，模拟用户登陆
* @author lin
*
*/
public class LoginService {
/**
* 用户登陆
* @param userName 用户名
* @return
*/
public String login(String userName)
{
return userName;
}
}
MessageService:
package com.dwrdemo.pojo;
import java.util.Collection;
import javax.servlet.ServletContext;
import org.directwebremoting.ScriptSession;
import org.directwebremoting.ServerContext;
import org.directwebremoting.ServerContextFactory;
import org.directwebremoting.WebContext;
import org.directwebremoting.WebContextFactory;
import org.directwebremoting.proxy.ScriptProxy;
public class MessageService {
public String sendMessage(String messageText,String toName) {
//Message message = createMessage(messageText, toName);
System.out.println(messageText+"\t\t\t"+toName);
postNewMessage(messageText, toName);
return null;
}
/**
* 获得前端脚本代理
* @return
*/
public ScriptProxy getScriptProxy() {
WebContext webContext = WebContextFactory.get();
ServletContext servletContext = webContext.getServletContext();
ServerContext serverContext = ServerContextFactory.get(servletContext);
webContext.getScriptSessionsByPage("");
/**
* 项目根路径
*/
String contextPath = servletContext.getContextPath();
if (contextPath != null) {
/**
* 获得当前访问该页面的全部脚本会话
*/
Collection<ScriptSession> sessions = serverContext.getScriptSessionsByPage(contextPath+"/index.jsp");
ScriptProxy proxy = new ScriptProxy(sessions);
return proxy;
}
return null;
}
/**
* 调用前端javascript函数
* @param newMessage
*/
public void postNewMessage(String message,String toName) {
ScriptProxy proxy = getScriptProxy();
if (proxy != null) {
/**
* 调用的前端函数名，和函数的参数
*/
System.out.println("NEW MESSAGE:"+message+"\t\t\t"+toName);
proxy.addFunctionCall("newMessage",message,toName);
}
}
}
项目目录结构：
运行结果：
我的这种一对一消息推送办法可能不是很好，如果有人有更好的解决方案，麻烦告诉我一下，谢谢！
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原文地址：http://my.oschina.net/u/2328736/blog/504677
