dwr+springboot实现java消息推送浏览器【无dwr配置文件】

由于本人在实际项目开发中有涉及到流程跑批，每个节点顺序点击执行后必须刷新页面才能看到状态是否变更。从客户体验上来说，这点是非常差的，于是想到dwr和websocket实现实时消息推送浏览器，前者是一个用于改善web页面与Java类交互的远程服务器端Ajax开源框架，它可以允许在浏览器里的代码使用运行在WEB服务器上的JAVA方法，就像它就在浏览器里一样，但存在一定的java代码泄露风险，而后者是一种网络双工通讯TCP协议，长连接，需要客户端发起连接。两者实现起来都是相对比较简单的，下面来简单实现下dwr！

实现步骤如下：

1、maven引jar   

<dependency>
   <groupId>org.directwebremoting</groupId>
   <artifactId>dwr</artifactId>
   <version>3.0.2-RELEASE</version>
</dependency>

2、dwr无xml配置部分

package com.paic.commcc.support.dwr;

import org.directwebremoting.Container;
import org.directwebremoting.create.NewCreator;
import org.directwebremoting.extend.Configurator;
import org.directwebremoting.extend.CreatorManager;

/**
 * @author 
 * @Package com.paic.commcc.support.dwr
 * @Description: dwr的xml配置
 * @date 2018/12/11 19:19
 */
public class DwrXml implements Configurator {

    @Override
    public void configure(Container container) {
        CreatorManager creatorManager = container.getBean(CreatorManager.class);
        NewCreator creator = new NewCreator();
        creator.setClass("com.paic.commcc.support.dwr.DwrPush");
        creator.setJavascript("DwrPush");
        creatorManager.addCreator(creator);
    }

}

3、dwr核心配置，注意标色代码部分是第2点的配置类路径

package com.paic.commcc.support.dwr;

import org.directwebremoting.servlet.DwrListener;
import org.directwebremoting.servlet.DwrServlet;
import org.springframework.boot.web.servlet.ServletListenerRegistrationBean;
import org.springframework.boot.web.servlet.ServletRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import java.util.HashMap;
import java.util.Map;

/**
 * @author 
 * @Package com.paic.commcc.support.dwr
 * @Description: 远程服务端ajax
 * @date 2018/12/11 19:17
 */
@Configuration
public class DwrConfig {
    @Bean
    public ServletRegistrationBean dwr() {
        ServletRegistrationBean servlet = new ServletRegistrationBean(new DwrServlet(), "/dwr/*");
        Map<String, String> initParam = new HashMap<>();
        initParam.put("crossDomainSessionSecurity", "false");
        initParam.put("allowScriptTagRemoting", "true");
        initParam.put("classes", "java.lang.Object");
        initParam.put("activeReverseAjaxEnabled", "true");
        initParam.put("initApplicationScopeCreatorsAtStartup", "true");
        initParam.put("maxWaitAfterWrite", "60000");
        initParam.put("debug", "true");
        initParam.put("logLevel", "WARN");
        //自定义配置，org.directwebremoting.impl.StartupUtil#configureFromInitParams name.equals("customConfigurator")
        //DwrServlet#init 初始化this.container
        initParam.put("customConfigurator", "com.paic.commcc.support.dwr.DwrXml");
        servlet.setInitParameters(initParam);
        return servlet;
    }

    @Bean
    public ServletListenerRegistrationBean dwrListener() {
        return new ServletListenerRegistrationBean(new DwrListener());
    }

}

4、dwr推送消息类

package com.paic.commcc.support.dwr;

import org.directwebremoting.Browser;
import org.directwebremoting.ScriptSession;
import org.directwebremoting.ScriptSessionFilter;
import org.directwebremoting.ScriptSessions;

/**
 * @author 
 * @Package com.paic.commcc.support.dwr
 * @Description: dwr推送消息类
 * @date 2018/12/11 19:23
 */
public class DwrPush {

    public static void init(String msg) {
        DwrPush.sendMsgToPage("/dwr.html", msg);
    }

    /**
     * @Description: 推送消息至页面，默认onDwrData函数
     * @Param: [html, msg]
     * @return: void
     * @Author: 
     * @Date: 2018/12/12
     */
    public static void sendMsgToPage(final String html, final String msg) {
        sendMsgToPage(html, "onDwrData", msg);
    }

    public static void sendMsgToPage(final String html, final String function, final String msg) {
        Browser.withPage(html, new Runnable() {
            public void run() {
                ScriptSessions.addFunctionCall(function, msg);
            }
        });
    }

    public static void sendMsgWithAllSessions(final String msg) {
        Browser.withAllSessions(new Runnable() {
            public void run() {
                ScriptSessions.addFunctionCall("onDwrData", msg);
            }
        });
    }

    public static void sendMsgWithFilter(final String msg) {
        Browser.withAllSessionsFiltered(new ScriptSessionFilter() {
            @Override
            public boolean match(ScriptSession scriptSession) {
                // 可以在这里做一些session过滤
                return true;
            }
        }, new Runnable() {
            public void run() {
                ScriptSessions.addFunctionCall("onDwrData", msg);
            }
        });
    }
}

5、dwr.html页面放static目录下，3个js，其中DwrPush.js的名字跟推送消息类一致，其他两个为框架本身的，必须要引用

<html>
<head>
    <title>dwr html</title>
    <script type='text/javascript' src='/dwr/engine.js'></script>
    <script type='text/javascript' src='/dwr/interface/DwrPush.js'></script>
    <script type='text/javascript' src='/dwr/util.js'></script>

    <script>
        window.onload = function () {
            dwr.engine.setActiveReverseAjax(true);//开启反向ajax
            dwr.engine.setNotifyServerOnPageUnload(true);//页面关闭通知服务器销毁当前会话scriptsession
            dwr.engine.setErrorHandler(function(msg) {
                alert(msg);
            });
            DwrPush.init("dwr hello");
        }
        function onDwrData(data) {
            alert(data);
        }
    </script>
</head>
<body>

dwr html
</body>
</html>

然后就可以实现后台有节点状态变更时，调用dwr消息推送类刷新浏览器节点状态了，怎么去刷新就看具体实现。

希望对你有所帮助，谢谢~

来源：oschina

链接：https://my.oschina.net/u/2697234/blog/2991385