dwr 推送消息

本文主要是介绍dwr 推送消息，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

dwr + spring 实时推送消息，通过网络技术学习，做了个小功能，总结如下：

1、下载dwr.jar

官网地址：http://directwebremoting.org/dwr/downloads/

下载最新版本v3.0

2、导入jar

3、配置web.xml

<!-- DWR配置 START -->
<servlet><description>This is the description of my J2EE component</description><display-name>This is the display name of my J2EE component</display-name><servlet-name>DWRServlet</servlet-name><servlet-class>org.directwebremoting.servlet.DwrServlet</servlet-class><!--commet 方式--><init-param><param-name>activeReverseAjaxEnabled</param-name><param-value>true</param-value></init-param><!--测试环境下,需要开启debug模式,线上环境需要关闭-->  <init-param><param-name>debug</param-name><param-value>false</param-value></init-param><!--允许跨域--><init-param><param-name>crossDomainSessionSecurity</param-name><param-value>false</param-value></init-param><!--允许脚本标签远程--> <init-param><param-name>allowScriptTagRemoting</param-name><param-value>true</param-value></init-param>
</servlet><servlet-mapping><servlet-name>DWRServlet</servlet-name><url-pattern>/dwr/*</url-pattern>
</servlet-mapping> <!-- DWR配置 END -->

4、由Spring管理dwr

配置applicationContext-common.xml

<!--由spring管理dwr   -->
<bean id="deviceInfo" class="com.dc.rcms.DWRDeviceInfoStatus"></bean>

5、页面引用以下js

<!--dwr消息推送 -->
<script type="text/javascript" src="dwr/engine.js"></script>
<script type="text/javascript" src="dwr/util.js"></script>

并且页面初始化，加

$(function(){    dwr.engine.setActiveReverseAjax(true);  dwr.engine.setNotifyServerOnPageUnload(true);
});

6、后台直接要推送的内容

public DWRDeviceInfoStatus(){//定时向前台推送设备信息Timer timer = new Timer();timer.schedule(new TimerTask() {@Overridepublic void run() {<span style="white-space:pre">	</span>try{ServerContext serverContext = ServerContextFactory.get();Container container = serverContext.getContainer();ScriptSessionManager manager = container.getBean(ScriptSessionManager.class);Collection sessions = manager.getAllScriptSessions();if(sessions.size() == 0 ){return;}//得到设备部位信息状态数量Util util = new Util(sessions);List<SEntity> list=baseDao.search("select count(id) as allnum,sum(case when status=1 then 1 end) as gznum,sum(case when status=0 then 1 end) as zcnum from rcms_device ",null);if(list!=null && list.size()>0){SEntity entity=list.get(0);String jsonStr="{\"allnum\":"+repaceNull(entity.getValueAsString("allnum"))+",\"gznum\":"+repaceNull(entity.getValueAsString("gznum"))+",\"zcnum\":"+repaceNull(entity.getValueAsString("zcnum"))+"}";util.addFunctionCall("showDeviceInfo", jsonStr);}//得到所有故障点信息Util utilgzd = new Util(sessions);List<SEntity> gzlist=baseDao.search("select device_code,count(id) n from rcms_device where status =1 group by device_code order by device_code", null);if(gzlist!=null && gzlist.size()>0){String gzdjsonStr="[";for(int i=0;i<gzlist.size();i++){SEntity gzdentity=gzlist.get(i);gzdjsonStr += "{";gzdjsonStr +="\"device_code\":\""+repaceNull(gzdentity.getValueAsString("DEVICE_CODE"))+"\",";gzdjsonStr +="\"gzdnum\":\""+repaceNull(gzdentity.getValueAsString("n"))+"\"";gzdjsonStr +="},";}gzdjsonStr = gzdjsonStr.substring(0,gzdjsonStr.length()-1);gzdjsonStr = gzdjsonStr+"]" ;utilgzd.addFunctionCall("showDeviceGzdInfo", gzdjsonStr);}}catch(Exception e){}}}, 10*1000, 1000*3);}

7、页面接收后台推送的消息

脚本处理

/* 后台自动推送设备信息 */
//显示设备正常与否信息
function showDeviceInfo(data){var jsonstr = eval( "(" + data + ")" );if(jsonstr!=null){$("#bottomcount").html("<p style=\"margin-left: 20px;margin-top: 20px; font-size: 16px;\">共<span id=\"allnum\" style=\"margin-left: 10px;margin-right: 10px;\">"+jsonstr.allnum+"</span>个   正常<span id=\"zcnum\" style=\"margin-left: 10px;margin-right: 10px;\"><a class=\"icon\" target=\"dialog\" rel=\"main\" title=\"设备部位的正常数量\" width=\"850\" height=\"500\" οnclick=\"getsitezc_gznum(0);\"><font color=\"green\">"+jsonstr.zcnum+"</font></a></span>个   故障<span id=\"gznum\" style=\"margin-left: 10px;margin-right: 10px;\"><a class=\"icon\" target=\"dialog\" rel=\"main\" title=\"设备部位码的故障数量\" width=\"850\" height=\"500\"οnclick=\"getsitezc_gznum(1);\"><font color=\"red\">"+jsonstr.gznum+"</font></a></span>个</p>");}
}
//显示所有故障点信息
function showDeviceGzdInfo(data){var gzdjsonstr = eval( "(" + data + ")" );if(gzdjsonstr!=null){$("#gzdcount").html("<ul>");for(var i=0; i<gzdjsonstr.length; i++) { $("#gzdcount").append("<a target=\"dialog\" rel=\"main\" title=\"设备部位的故障点数量\" width=\"850\" height=\"500\" οnclick=\"getsitegzdnum('"+gzdjsonstr[i].device_code+"');\"><li style=\"list-style-type:none;\"><img alt=\"警示\" src=\"img/warning.png\"/><span id=\"gzsnum\" style=\"margin-left: 5px;margin-top: 20px; font-size: 14px;\">"+gzdjsonstr[i].device_code+"  (  故障  <span style=\"margin-left: 5px;margin-right: 5px;margin-top: 10px;\"><font color=\"red\" >"+gzdjsonstr[i].gzdnum + "</font></span>个)</span></li></a></ul>");}}isfirst=2;
}

页面如下