DWR反向Ajax的一个简单Web聊天

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web.xml文件的配置

Xml代码

1. <?xml version="1.0" encoding="GBK"?>

2. <web-app xmlns="http://java.sun.com/xml/ns/javaee"

3. xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

4. xsi:schemaLocation="http://java.sun.com/xml/ns/javaee

5. http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" version="2.5">

6.

7. <servlet>

8.

9. <servlet-name>dwr-invoker</servlet-name>

10.

11. <servlet-class>org.directwebremoting.servlet.DwrServlet</servlet-class>

12.

13. <init-param>

14. <param-name>debug</param-name>

15. <param-value>true</param-value>

16. </init-param>

17.

18. <init-param>

19. <param-name>pollAndCometEnabled</param-name>

20. <param-value>true</param-value>

21. </init-param>

22. <load-on-startup>1</load-on-startup>

23. </servlet>

24.

25. <servlet-mapping>

26. <servlet-name>dwr-invoker</servlet-name>

27.

28. <url-pattern>/dwr/*</url-pattern>

29. </servlet-mapping>

30. </web-app>

Java处理类

Java代码

1. package com.lbx.dwr.chat;

3. import java.util.Collection;

4. import java.util.LinkedList;

6. import org.directwebremoting.WebContext;

7. import org.directwebremoting.WebContextFactory;

8. import org.directwebremoting.proxy.dwr.Util;

10. public class JavaChat

11. {

12. //保存聊天信息的List对象

13. private LinkedList<ChatMsg> messages = new LinkedList<ChatMsg>();

14.

15. public void addMessage(String text)

16. {

17. if (text != null && text.trim().length() > 0)

18. {

19. messages.addFirst(new ChatMsg(text));

20. //最多保留10条聊天记录

21. while (messages.size() > 10)

22. {

23. messages.removeLast();

24. }

25. }

26. WebContext wctx = WebContextFactory.get();

27. //以当前WebContext关联的ScriptSession创建Util

28. Util utilThis = new Util(wctx.getScriptSession());

29. //使用utilThis清除text文本框的内容

30. utilThis.setValue("text", "");

31. //获取当前页面的url

32. String currentPage = wctx.getCurrentPage();

33. //获取正在浏览当前页的所有浏览器会话

34. Collection sessions = wctx.getScriptSessionsByPage(currentPage);

35. //以sessions创建Util对象

36. Util utilAll = new Util(sessions);

37. //删除chatlog列表里的所有列表项

38. utilAll.removeAllOptions("chatlog");

39. //使用messages集合里集合元素的text属性为chatlog添加列表项

40. utilAll.addOptions("chatlog" , messages , "text");

41. }

42. }

Java代码

1. package com.lbx.dwr.chat;

3. public class ChatMsg

4. {

5. //ChatMsg包装的字符串

6. private String text;

7. public ChatMsg()

8. {

9. }

10.

11. public ChatMsg(String text)

12. {

13. this.text = text;

14. }

15. //text属性的setter和gette方法

16. public void setText(String text)

17. {

18. this.text = text;

19. }

20. public String getText()

21. {

22. return text;

23. }

24. }

dwr.xml文件的配置

Xml代码

1. <?xml version="1.0" encoding="UTF-8"?>

2. <!DOCTYPE dwr PUBLIC "-//GetAhead Limited//DTD Direct Web Remoting 2.0//EN"

3. "http://getahead.ltd.uk/dwr/dwr20.dtd">

4. <dwr>

5. <allow>

6. <create creator="new" javascript="chat" scope="application">

7. <param name="class" value="com.lbx.dwr.chat.JavaChat"/>

8. </create>

9. <convert converter="bean" match="com.lbx.dwr.chat.ChatMsg"/>

10. </allow>

11. </dwr>

客户端JSP代码

Html代码

1. <%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>

2. <%

3. String path = request.getContextPath();

4. String basePath = request.getScheme() + "://"

5. + request.getServerName() + ":" + request.getServerPort()

6. + path + "/";

7. %>

9. <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"

10. "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

11. <html xmlns="http://www.w3.org/1999/xhtml">

12. <head>

13. <title>反向Ajax的聊天室</title>

14. <meta name="website" content="http://www.crazyit.org" />

15. <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />

16. <script type='text/javascript' src='dwr/engine.js'></script>

17. <script type='text/javascript' src='dwr/interface/chat.js'></script>

18. <script type='text/javascript' src='dwr/util.js'></script>

19. <script type="text/javascript">

20. function sendMessage()

21. {

22. //调用远程Java方法，无需回调函数

23. chat.addMessage(dwr.util.getValue("text"));

24. }

25. </script>

26. </head>

27.

28. <body onload="dwr.engine.setActiveReverseAjax(true);">

29.

30. <h3>

31. 反向Ajax的聊天室

32. </h3>

33. <div style="width: 460px; height: 200px; border: 1px solid #999999">

34. <ul id="chatlog"></ul>

35. </div>

36. <br />

37. 输入您的聊天信息:

38. <input id="text" onkeypress="dwr.util.onReturn(event, sendMessage);"/>

39. <input type="button" value="发送" onclick="sendMessage()" />

40. </body>

41. </html>

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