DWR推送–HelloWorld详解编程语言

servlet-name dwr-invoke /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 initApplicationScopeCreatorsAtStartup /param-name param-value true /param-value /init-param load-on-startup 1 /load-on-startup /servlet servlet-mapping servlet-name dwr-invoke /servlet-name url-pattern /dwr/* /url-pattern /servlet-mapping !-- End -- 配置dwr.xml (放在和web.xml 同一个目录)

 !DOCTYPE dwr PUBLIC 

 "-//GetAhead Limited//DTD Direct Web Remoting 1.0//EN" 

 "http://www.getahead.ltd.uk/dwr/dwr10.dtd" 

 dwr 

 !--定义了DWR能够创建和转换的类，以供 javascript 访问。-- 

 allow 

 !-- create 标签中指定 javascript 中可以访问的 java 类，并定义 dwr 应当如何获得要进行远程的类的实例。 

 其中 javascript=" testClass " 属性指定 javascript 代码访问对象时使用的名称。 

 creator是类构造器，creator="new" 属性指定 java 类实例的生成方式， new 意味着 DWR 应当调用类的默认构造函数来获得实例，其他的还有 spring 方式，通过与 IOC 容器 Spring 进行集成来获得实例等等。 -- 

 create creator="new" javascript="CheckUserStatus" 

 param name="class" value="com.lb.mil.service.CheckUserStatusService"/ 

 /create 

 /allow 

 /dwr 

编写CheckUserStatusService

package com.lb.mil.service; 

import com.alibaba.fastjson.JSON; 

import com.lb.common.data.json.StatusResult; 

import com.lb.common.utils.ObjectUtils; 

import com.lb.mil.cache.EHCacheConfig; 

import com.lb.mil.cache.EHCacheUtil; 

import com.lb.mil.cache.data.UserState; 

import com.lb.mil.entity.MilInformation; 

import com.lb.mil.entity.MilInformationAttach; 

import org.directwebremoting.ScriptBuffer; 

import org.directwebremoting.ScriptSession; 

import org.directwebremoting.WebContext; 

import org.directwebremoting.WebContextFactory; 

import org.directwebremoting.proxy.dwr.Util; 

import org.slf4j.Logger; 

import org.slf4j.LoggerFactory; 

import java.util.ArrayList; 

import java.util.Collection; 

import java.util.List; 

 * Created by Administrator on 2016/7/18. 

public class CheckUserStatusService 

 protected Logger logger = LoggerFactory.getLogger(CheckUserStatusService.class); 

 public void check() 

 //获取上线下线人员 

 //添加逻辑 

 ScriptBuffer scriptBuffer = new ScriptBuffer(); //构造js脚本 

 WebContext webContext= WebContextFactory.get(); 

 String currentPage = webContext.getCurrentPage(); 

 ScriptSession myScSession = webContext.getScriptSession(); 

 if(ObjectUtils.isNotNull(offLineIds)||ObjectUtils.isNotNull(onlineIds)) 

 //调用页面的show方法 

 scriptBuffer.appendScript("show(") 

 .appendData(JSON.toJSONString(statusResult)) 

 .appendScript(");"); 

 //获取所有浏览当前页面的脚本session 

 Collection ScriptSession sessions = webContext.getScriptSessionsByPage(currentPage); 

 //获取请求页面的脚本session 

 //ScriptSession sessions = webContext.getScriptSession(); 

 Util util = new Util(sessions); 

 util.addScript(scriptBuffer); 

引用js文件(直接引用就行，路径dwr/是web.xml里面里的值，最后一个js，CheckUserStatus.js是dwr.xml里面create javascript属性值)

 script type=text/javascript src=${pageContext.request.contextPath }/dwr/engine.js /script 

 script type=text/javascript src=${pageContext.request.contextPath }/dwr/util.js /script 

 script type=text/javascript src=${pageContext.request.contextPath }/dwr/interface/CheckUserStatus.js /script 

页面body 里添加：

 body onload="dwr.engine.setActiveReverseAjax(true);dwr.engine.setNotifyServerOnPageUnload(true,true);dwr.engine.setErrorHandler(function(){});"