学步园

         第一、在项目中引入dwr.jar，然后在web.xml中进行配置，配置如下：

Java代码
 

1. <servlet>  
2.   
3.         <servlet-name>dwr-invoker</servlet-name>  
4.   
5.         <servlet-class>  
6.   
7.             org.directwebremoting.servlet.DwrServlet  
8.   
9.         </servlet-class>  
10.   
11.         <init-param>  
12.   
13.             <param-name>crossDomainSessionSecurity</param-name>  
14.   
15.                <param-value>false</param-value>  
16.   
17.             </init-param>  
18.   
19.         <init-param>  
20.   
21.           <param-name>allowScriptTagRemoting</param-name>  
22.   
23.           <param-value>true</param-value>  
24.   
25.         </init-param>  
26.   
27.         <init-param>  
28.   
29.           <param-name>classes</param-name>  
30.   
31.           <param-value>java.lang.Object</param-value>  
32.   
33.         </init-param>  
34.   
35.         <init-param>  
36.   
37.             <param-name>activeReverseAjaxEnabled</param-name>  
38.   
39.             <param-value>true</param-value>  
40.   
41.         </init-param>  
42.   
43.         <init-param>  
44.   
45.            <param-name>initApplicationScopeCreatorsAtStartup</param-name>  
46.   
47.            <param-value>true</param-value>  
48.   
49.         </init-param>  
50.   
51.         <init-param>  
52.   
53.             <param-name>maxWaitAfterWrite</param-name>  
54.   
55.             <param-value>3000</param-value>  
56.   
57.         </init-param>  
58.   
59.         <init-param>  
60.   
61.             <param-name>debug</param-name>  
62.   
63.             <param-value>true</param-value>  
64.   
65.         </init-param>  
66.   
67.         <init-param>  
68.   
69.             <param-name>logLevel</param-name>  
70.   
71.             <param-value>WARN</param-value>  
72.   
73.         </init-param>  
74.   
75.     </servlet>  

<servlet>

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

        <servlet-class>

            org.directwebremoting.servlet.DwrServlet

        </servlet-class>

        <init-param>

            <param-name>crossDomainSessionSecurity</param-name>

               <param-value>false</param-value>

            </init-param>

        <init-param>

          <param-name>allowScriptTagRemoting</param-name>

          <param-value>true</param-value>

        </init-param>

        <init-param>

          <param-name>classes</param-name>

          <param-value>java.lang.Object</param-value>

        </init-param>

        <init-param>

            <param-name>activeReverseAjaxEnabled</param-name>

            <param-value>true</param-value>

        </init-param>

        <init-param>

           <param-name>initApplicationScopeCreatorsAtStartup</param-name>

           <param-value>true</param-value>

        </init-param>

        <init-param>

            <param-name>maxWaitAfterWrite</param-name>

            <param-value>3000</param-value>

        </init-param>

        <init-param>

            <param-name>debug</param-name>

            <param-value>true</param-value>

        </init-param>

        <init-param>

            <param-name>logLevel</param-name>

            <param-value>WARN</param-value>

        </init-param>

    </servlet>

   第二：在web.xml的同级目录下新建dwr.xml文件，内容如下

Java代码
 

1. <!DOCTYPE dwr PUBLIC  
2.      "-//GetAhead Limited//DTD Direct Web Remoting 3.0//EN"  
3.      "http://getahead.org/dwr/dwr30.dtd">  
4.   
5. <dwr>  
6.      <alow>  
7.           <create creator="new" javascript="MessagePush">  
8.             <param name="class" value="com.huatech.messageremind.service.MessagePush"/>  
9.          </create>  
10.           <create creator="new" javascript="TestPush">  
11.             <param name="class" value="com.huatech.messageremind.service.Test"/>  
12.          </create>  
13.      </alow>  
14. </dwr>  

<!DOCTYPE dwr PUBLIC
     "-//GetAhead Limited//DTD Direct Web Remoting 3.0//EN"
     "http://getahead.org/dwr/dwr30.dtd">

<dwr>
     <alow>
          <create creator="new" javascript="MessagePush">
            <param name="class" value="com.huatech.messageremind.service.MessagePush"/>
         </create>
          <create creator="new" javascript="TestPush">
            <param name="class" value="com.huatech.messageremind.service.Test"/>
         </create>
     </alow>
</dwr>

   这个是dwr的基本配置，MessagePush在页面的javascript中使用，这个是对被推送页面开放的java类，Test是对推送页面开放的java类。场景：管理员后台登陆，发布一条消息，通过Test推送到后台，后台通过MessagePush推送给指定的用户，当然，至于怎么找到指定的用户，下面会说。

     第三，被推送的页面代码

Java代码
 

1. <%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>  
2. <%  
3. String path = request.getContextPath();  
4. String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";  
5. %>  
6. <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">  
7. <html>  
8.   <head>  
9.     <base href="<%=basePath%>">  
10.     <title>DWR  DEMO</title>  
11.     <meta http-equiv="pragma" content="no-cache">  
12.     <meta http-equiv="cache-control" content="no-cache">  
13.     <meta http-equiv="expires" content="0">      
14.     <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">  
15.     <meta http-equiv="description" content="This is my page">  
16.   </head>  
17.   <script type='text/javascript' src='dwr/engine.js'></script>  
18.   <script type='text/javascript' src='dwr/util.js'></script>  
19.   <script type="text/javascript" src="dwr/interface/MessagePush.js"></script>  
20.   
21.   <script type="text/javascript">  
22.         //通过该方法与后台交互，确保推送时能找到指定用户  
23.          function onPageLoad(){  
24.             var userId = '${userinfo.humanid}';  
25.             MessagePush.onPageLoad(userId);  
26.   
27.           }  
28.          //推送信息  
29.          function showMessage(autoMessage){  
30.                 alert(autoMessage);  
31.                   
32.         }  
33.   </script>  
34.   <body onload="onPageLoad();dwr.engine.setActiveReverseAjax(true);dwr.engine.setNotifyServerOnPageUnload(true);;">   
35.     This is my DWR DEOM page. <hr>  
36.     <br>  
37.     <div id="DemoDiv">demo</div>  
38.   </body>  
39. </html>  

<%@ 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">
  </head>
  <script type='text/javascript' src='dwr/engine.js'></script>
  <script type='text/javascript' src='dwr/util.js'></script>
  <script type="text/javascript" src="dwr/interface/MessagePush.js"></script>

  <script type="text/javascript">
  		//通过该方法与后台交互，确保推送时能找到指定用户
         function onPageLoad(){
            var userId = '${userinfo.humanid}';
            MessagePush.onPageLoad(userId);

          }
         //推送信息
		 function showMessage(autoMessage){
				alert(autoMessage);
				
		}
  </script>
  <body onload="onPageLoad();dwr.engine.setActiveReverseAjax(true);dwr.engine.setNotifyServerOnPageUnload(true);;"> 
    This is my DWR DEOM page. <hr>
    <br>
    <div id="DemoDiv">demo</div>
  </body>
</html>

    以上代码的简单解释：

     页面页面onload的3个函数都是必须的，后两个是dwr的，第一个是将登录用户的userid与对应   的scriptSession进行处理，以便精确推送的时候能找到推送对象

第四 MessagePush类中实现的方法如下：

Java代码
 

1.      public void onPageLoad(String userId) {  
2.   
3.        ScriptSession scriptSession = WebContextFactory.get().getScriptSession();  
4.   
5.        scriptSession.setAttribute(userId, userId);  
6.   
7.        DwrScriptSessionManagerUtil dwrScriptSessionManagerUtil = new DwrScriptSessionManagerUtil();  
8.   
9.        try {  
10.   
11.               dwrScriptSessionManagerUtil.init();  
12.               System.out.println("cacaca");  
13.   
14.        } catch (ServletException e) {  
15.   
16.               e.printStackTrace();  
17.   
18.        }  
19.   
20. }  

      public void onPageLoad(String userId) {

        ScriptSession scriptSession = WebContextFactory.get().getScriptSession();

        scriptSession.setAttribute(userId, userId);

        DwrScriptSessionManagerUtil dwrScriptSessionManagerUtil = new DwrScriptSessionManagerUtil();

        try {

               dwrScriptSessionManagerUtil.init();
               System.out.println("cacaca");

        } catch (ServletException e) {

               e.printStackTrace();

        }

 }

里面对应的DwrScriptSessionManagerUtil
对应如下：

Java代码
 

1. import javax.servlet.ServletException;  
2. import javax.servlet.http.HttpSession;  
3.   
4. import org.directwebremoting.Container;  
5. import org.directwebremoting.ServerContextFactory;  
6. import org.directwebremoting.WebContextFactory;  
7. import org.directwebremoting.event.ScriptSessionEvent;  
8. import org.directwebremoting.event.ScriptSessionListener;  
9. import org.directwebremoting.extend.ScriptSessionManager;  
10. import org.directwebremoting.servlet.DwrServlet;  
11.   
12. public class DwrScriptSessionManagerUtil extends DwrServlet{  
13.   
14.     private static final long serialVersionUID = -7504612622407420071L;  
15.   
16.     public void init()throws ServletException {  
17.   
18.            Container container = ServerContextFactory.get().getContainer();  
19.            ScriptSessionManager manager = container.getBean(ScriptSessionManager.class);  
20.            ScriptSessionListener listener = new ScriptSessionListener() {  
21.                   public void sessionCreated(ScriptSessionEvent ev) {  
22.                          HttpSession session = WebContextFactory.get().getSession();  
23.   
24.                          String userId =((User) session.getAttribute("userinfo")).getHumanid()+"";  
25.                          System.out.println("a ScriptSession is created!");  
26.                          ev.getSession().setAttribute("userId", userId);  
27.                   }  
28.                   public void sessionDestroyed(ScriptSessionEvent ev) {  
29.                          System.out.println("a ScriptSession is distroyed");  
30.                   }  
31.            };  
32.            manager.addScriptSessionListener(listener);  
33.     }  
34. }  

import javax.servlet.ServletException;
import javax.servlet.http.HttpSession;

import org.directwebremoting.Container;
import org.directwebremoting.ServerContextFactory;
import org.directwebremoting.WebContextFactory;
import org.directwebremoting.event.ScriptSessionEvent;
import org.directwebremoting.event.ScriptSessionListener;
import org.directwebremoting.extend.ScriptSessionManager;
import org.directwebremoting.servlet.DwrServlet;

public class DwrScriptSessionManagerUtil extends DwrServlet{

    private static final long serialVersionUID = -7504612622407420071L;

    public void init()throws ServletException {

           Container container = ServerContextFactory.get().getContainer();
           ScriptSessionManager manager = container.getBean(ScriptSessionManager.class);
           ScriptSessionListener listener = new ScriptSessionListener() {
                  public void sessionCreated(ScriptSessionEvent ev) {
                         HttpSession session = WebContextFactory.get().getSession();

                         String userId =((User) session.getAttribute("userinfo")).getHumanid()+"";
                         System.out.println("a ScriptSession is created!");
                         ev.getSession().setAttribute("userId", userId);
                  }
                  public void sessionDestroyed(ScriptSessionEvent ev) {
                         System.out.println("a ScriptSession is distroyed");
                  }
           };
           manager.addScriptSessionListener(listener);
    }
}

 第五 推送页面代码：

Java代码
 

1. <%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>  
2. <%  
3. String path = request.getContextPath();  
4. String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";  
5. %>  
6. <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">  
7. <html>  
8.   <head>  
9.     <base href="<%=basePath%>">  
10.     <title>My JSP 'MyJsp.jsp' starting page</title>  
11.     <meta http-equiv="pragma" content="no-cache">  
12.     <meta http-equiv="cache-control" content="no-cache">  
13.     <meta http-equiv="expires" content="0">      
14.     <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">  
15.     <meta http-equiv="description" content="This is my page">  
16.     <script type="text/javascript" src="<%=request.getContextPath() %>/js/jquery-1.5.1.js"></script>  
17.     <script type='text/javascript' src='dwr/engine.js'></script>  
18.     <script type='text/javascript' src='dwr/util.js'></script>  
19.     <script type='text/javascript' src='dwr/interface/TestPush.js'></script>  
20.       
21.     <script type="text/javascript">  
22.       
23.     function test() {  
24.         var msg = document.getElementById("msgId").value;  
25.         //msg = {msgId: '1', context: $("#msgContext").val()};  
26.         TestPush.sendMessageAuto(msg,"哈哈哈");  
27.           
28.     }  
29.     </script>  
30.   </head>  
31.     
32.   <body>  
33.     id&nbsp;&nbsp;&nbsp;&nbsp;: <input type="text" name="msgId" id="msgId" /> <br />  
34.      
35.     <input type="button" value="Send" onclick="test()"  />  
36.       
37.   </body>  
38. </html>  

<%@ 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>My JSP 'MyJsp.jsp' starting page</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">
	<script type="text/javascript" src="<%=request.getContextPath() %>/js/jquery-1.5.1.js"></script>
	<script type='text/javascript' src='dwr/engine.js'></script>
	<script type='text/javascript' src='dwr/util.js'></script>
	<script type='text/javascript' src='dwr/interface/TestPush.js'></script>
	
	<script type="text/javascript">
	
	function test() {
		var msg = document.getElementById("msgId").value;
		//msg = {msgId: '1', context: $("#msgContext").val()};
		TestPush.sendMessageAuto(msg,"哈哈哈");
		
	}
	</script>
  </head>
  
  <body>
    id&nbsp;&nbsp;&nbsp;&nbsp;: <input type="text" name="msgId" id="msgId" /> <br />
   
   	<input type="button" value="Send" onclick="test()"  />
   	
  </body>
</html>

 第六：精确推送要实现的代码：

Java代码
 

1. public class Test{  
2.     public void sendMessageAuto(String userid, String message){  
3.           
4.         final String userId = userid;  
5.         final String autoMessage = message;  
6.         Browser.withAllSessionsFiltered(new ScriptSessionFilter() {  
7.             public boolean match(ScriptSession session){  
8.                 if (session.getAttribute("userId") == null)  
9.                     return false;  
10.                 else  
11.                     return (session.getAttribute("userId")).equals(userId);  
12.             }  
13.         }, new Runnable(){  
14.               
15.             private ScriptBuffer script = new ScriptBuffer();  
16.               
17.             public void run(){  
18.                   
19.                 script.appendCall("showMessage", autoMessage);  
20.                   
21.                 Collection<ScriptSession> sessions = Browser  
22.   
23.                 .getTargetSessions();  
24.                   
25.                 for (ScriptSession scriptSession : sessions){  
26.                     scriptSession.addScript(script);  
27.                 }  
28.             }  
29.         });  
30.     }  
31. }  

public class Test{
    public void sendMessageAuto(String userid, String message){
        
        final String userId = userid;
        final String autoMessage = message;
        Browser.withAllSessionsFiltered(new ScriptSessionFilter() {
            public boolean match(ScriptSession session){
                if (session.getAttribute("userId") == null)
                    return false;
                else
                    return (session.getAttribute("userId")).equals(userId);
            }
        }, new Runnable(){
            
            private ScriptBuffer script = new ScriptBuffer();
            
            public void run(){
                
                script.appendCall("showMessage", autoMessage);
                
                Collection<ScriptSession> sessions = Browser

                .getTargetSessions();
                
                for (ScriptSession scriptSession : sessions){
                    scriptSession.addScript(script);
                }
            }
        });
    }
}

 至此   这个例子的代码都已经贴出来了，应该是可以跑通的，有问题的话可以给我留言。当然，要自己写个登录，然后把userId放到session里面，这个比较简单，就不贴代码了，有问题可以在http://download.csdn.net/detail/luojia_wang/5275588上下载原项目。我只是简单的做了一个能实现功能的例子，还有很多地方要研究，比如跟spring整合，还可能有很多优化，等我继续学习一下再说.