您的位置：首页 > 其它

使用DWR实现消息推送功能

2018-02-28 18:10 627 查看

参考：http://blog.csdn.net/carefree31441/article/details/17225851

添加Maven依赖：

<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>3.8.1</version>
<scope>test</scope>
</dependency>
<!-- https://mvnrepository.com/artifact/org.directwebremoting/dwr -->
<dependency>
<groupId>org.directwebremoting</groupId>
<artifactId>dwr</artifactId>
<version>3.0.0-RELEASE</version>
</dependency>
<dependency>
<groupId>commons-logging</groupId>
<artifactId>commons-logging</artifactId>
<version>1.2</version>
</dependency>

</dependencies>

新建一个ScriptSessionListener：监听ScriptSession的创建和销毁

public class DWRScriptSessionListener implements ScriptSessionListener {
// 维护一个Map key为session的Id， value为ScriptSession对象
public static final Map<String, ScriptSession> scriptSessionMap = new HashMap<String, ScriptSession>();

public void sessionCreated(ScriptSessionEvent event) {
WebContext webContext = WebContextFactory.get();
HttpSession session = webContext.getSession();
ScriptSession scriptSession = event.getSession();
scriptSession.setAttribute("userid", session.getId());//这里使用sesssion,使用时可存储为用户id后使用
scriptSessionMap.put(session.getId(), scriptSession); // 添加scriptSession
System.out.println("session-created"+session.getId());
}

public void sessionDestroyed(ScriptSessionEvent event) {
WebContext webContext = WebContextFactory.get();
HttpSession session = webContext.getSession();
scriptSessionMap.remove(session.getId()); // 移除scriptSession
}
}

继承DefaultScriptSessionManager，添加ScriptSession监听器

public class DWRScriptSessionManager extends DefaultScriptSessionManager {
public DWRScriptSessionManager(){
//绑定一个ScriptSession增加销毁事件的监听器
this.addScriptSessionListener( new DWRScriptSessionListener());
}
}

Web全局配置：web.xml

<web-app>
<display-name>DWR-START</display-name>
<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>
<init-param>
<param-name>activeReverseAjaxEnabled</param-name>
<param-value>true</param-value>
</init-param>
<init-param>
<param-name>org.directwebremoting.extend.ScriptSessionManager </param-name>
<param-value>gdou.laiminghai.dwr.DWRScriptSessionManager </param-value>
</init-param>
</servlet>
<servlet-mapping>
<servlet-name>dwr-invoker</servlet-name>
<url-pattern>/dwr/*</url-pattern>
</servlet-mapping>
</web-app>

消息推送功能类

public class MessagePush {
//改善给特定用户
public void sendToOne(final String userId, final String 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", message);
Collection<ScriptSession> sessions = Browser.getTargetSessions();
for (ScriptSession scriptSession : sessions) {
scriptSession.addScript(script);
}
}
});
}

//发送给所有用户
public void sendToAll(final String message) {
Browser.withAllSessions(new Runnable() {
public void run() {
ScriptSessions.addFunctionCall("showMessage", message);
}
});
}
}

DWR配置：在web.xml同一目录下新建dwr.xml

<dwr>
<allow><!--定义了DWR能够创建和转换的类，以供 javascript 访问-->
<create creator="new" javascript="MessagePush">
<param name="class" value="gdou.laiminghai.dwr.MessagePush" />
</create>
</allow>
</dwr>

页面

<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
</head>
<body>
<div>sessionid:<input id="sessionid" type="text">message:<input id="msg" type="text">
<input type="button" onclick="sendToOne();" value="发送"></div>
<div>message:<input id="msg2" type="text">
<input type="button" onclick="sendToAll();" value="发送给所有人"></div>
<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">
dwr.engine.setActiveReverseAjax(true);
dwr.engine.setNotifyServerOnPageUnload(true);

//回调函数
function showMessage(message) {
alert(message);
}

function sendToOne(){
var sessionid = document.getElementById("sessionid").value;
var msg = document.getElementById("msg").value;
MessagePush.sendToOne(sessionid,msg);
}

function sendToAll(){
var msg2 = document.getElementById("msg2").value;
MessagePush.sendToAll(msg2);
}
</script>
</body>
</html>

内容来自用户分享和网络整理，不保证内容的准确性，如有侵权内容，可联系管理员处理

标签： dwr 消息推送

相关文章推荐

新的分享

章节导航