基于dwr的消息推送java web

川长思鸟来 2022-12-10 14:54 132阅读 0赞

1.  pom.xml 加依赖
    
        
            <dependency>
                <groupId>org.directwebremoting</groupId>
                <artifactId>dwr</artifactId>
                <version>3.0.0-RELEASE</version>
            </dependency>
2.  web.xml
    
        
        <servlet>
            <display-name>DWR Servlet</display-name>
            <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>pollAndCometEnabled</param-name>
                <param-value>true</param-value>
            </init-param>
            <load-on-startup>1</load-on-startup>
        </servlet>
        
        <servlet-mapping>
            <servlet-name>dwr-invoker</servlet-name>
            <url-pattern>/dwr/*</url-pattern>
        </servlet-mapping>
        
3.  dwr.xml（和web.xml同目录） 注意这里的javascript命名必须和前端导入的js名字一致
    
        <!DOCTYPE dwr PUBLIC
            "-//GetAhead Limited//DTD Direct Web Remoting 3.0//EN"
            "http://getahead.org/dwr/dwr30.dtd">
        
        <dwr>
        <allow>
            
            <create creator="new" javascript="SendMsg">
                <param name="class">cc.gukeer.common.dwr.SendMsg</param>
            </create>
        </allow>
        </dwr>
4.  cc.gukeer.common.dwr.SendMsg
    
        package cc.gukeer.common.dwr;
        
        import org.directwebremoting.Browser;
        import org.directwebremoting.ScriptBuffer;
        import org.directwebremoting.ScriptSession;
        import org.directwebremoting.ScriptSessionFilter;
        
        import javax.servlet.ServletException;
        import java.util.Collection;
        import java.util.List;
        
        /**
         * Created by Administrator on 2017/5/22.
         */
        public class SendMsg {
            public void send(final String msg,final List<String> uid) {
        
                //过滤器
                ScriptSessionFilter filter = new ScriptSessionFilter() {
                    public boolean match(ScriptSession scriptSession) {
                        Object userid= scriptSession.getAttribute("uid");
                        if (userid == null)
                            return false;
                        return uid.contains(userid.toString());
                    }
                };
        
        
                Runnable run = new Runnable() {
                    private ScriptBuffer script = new ScriptBuffer();
        
                    @Override
                    public void run() {
                        script.appendCall("show", msg);
        
                        Collection<ScriptSession> sessions = Browser.getTargetSessions();
        
                        for (ScriptSession scriptSession : sessions) {
                            scriptSession.addScript(script);
                        }
        
                    }
                };
                Browser. withAllSessionsFiltered(filter, run);    //注意这里调用了有filter功能的方法
        
            }
        
            public void init() throws ServletException {
                InitUtil initUtil = new InitUtil();
                initUtil.init();
            }
        
        }
5.  InitUtil.java
    
        package cc.gukeer.common.dwr;
        
        import cc.gukeer.smartBoard.persistence.entity.User;
        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;
        
        import javax.servlet.ServletException;
        import javax.servlet.http.HttpSession;
        
        /**
         * Created by lx on 2017/3/3.
         */
        public class InitUtil extends DwrServlet {
            @Override
            public void init() throws ServletException {
                Container container = ServerContextFactory.get().getContainer();
                // 工厂方法get()返回ServerContext实例
                ScriptSessionManager manager = container.getBean(ScriptSessionManager.class);
                ScriptSessionListener listener = new ScriptSessionListener() {
                    public void sessionCreated(ScriptSessionEvent ev) {
                        HttpSession session = WebContextFactory.get().getSession();
                        User user = (User) session.getAttribute("loginUser");
                        ev.getSession().setAttribute("uid",  user.getId());
                    }
                    public void sessionDestroyed(ScriptSessionEvent ev) {
                        ev.getSession().removeAttribute("uid");
                    }
                };
                manager.addScriptSessionListener(listener);
            }
            }
6.  后端调用
    
        List<String> users = new ArrayList<String>();
            users.add("6");
            users.add("7");
        
            new SendMsg().send("测试成功",users);
7.  页面 注意这三个文件，第三个文件本地不存在，但是它的名字必须和 dwr里定义的那个名字一样，参考第二步骤
    
        <script type="text/javascript" src="${ctx}/dwr/engine.js"></script>
        <script type="text/javascript" src="${ctx}/dwr/util.js"></script>
        <script type="text/javascript" src="${ctx}/dwr/interface/SendMsg.js"></script>
        
        <script>
        dwr.engine.setActiveReverseAjax(true);
        
        dwr.engine.setNotifyServerOnPageUnload(true);
        
        function show(msg) {
            alert(msg);
        }
        
         $(function() {
        
            SendMsg.init();//将当前的uid存到scriptSession中
          });
        
        </script>

基于dwr的消息推送java web

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