配置使用dwr完成收邮件提示

DWR（Direct Web Remoting）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，可以帮助开发人员开发包含AJAX技术的网站。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函数，就像它就在浏览器里一样。

其实这些配置也是网上大神们的，只是拿出来整理下，少走弯路。

首先需要导入dwr3.0.jar，

然后在web.xml中加入

<!-- dwr配置 -->
    <servlet>

        <servlet-name>dwr-invoker</servlet-name>

        <servlet-class>

            org.directwebremoting.servlet.DwrServlet

        </servlet-class>

       <init-param>

            <param-name>crossDomainSessionSecurity</param-name>

               <param-value>false</param-value>

            </init-param>

        <init-param>

          <param-name>allowScriptTagRemoting</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>

        <init-param>

            <param-name>maxWaitAfterWrite</param-name>

            <param-value>3000</param-value>

        </init-param>

        <init-param>

            <param-name>debug</param-name>

            <param-value>false</param-value>

        </init-param>

        <init-param>

            <param-name>logLevel</param-name>

            <param-value>WARN</param-value> 

        </init-param>

    </servlet>
    <servlet-mapping>
        <servlet-name>dwr-invoker</servlet-name>
        <url-pattern>/dwr/*</url-pattern>
    </servlet-mapping>  

在webapps下新建dwr.xml（文件名不能改）

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE dwr PUBLIC "-//GetAhead Limited//DTD Direct Web Remoting 3.0//EN" "http://getahead.org/dwr/dwr30.dtd">

     <dwr>

          <allow>

               <create creator="new" javascript="MessagePush">

                 <param name="class" value="cn.qnight.common.MessagePush"/>

              </create>

          </allow>

     </dwr>

再新建一个MessagePush.java就完成dwr的配置，但是我们需要做收邮件提示得还需要一些改进。

新建 DwrScriptSessionManagerUtil.java

public class DwrScriptSessionManagerUtil extends DwrServlet {

    private static final long serialVersionUID = -7504612622407420071L;

    public void init()

            throws ServletException {

        Container container = ServerContextFactory.get().getContainer();

        ScriptSessionManager manager = container

                .getBean(ScriptSessionManager.class);

        ScriptSessionListener listener = new ScriptSessionListener() {

            public void sessionCreated(ScriptSessionEvent ev) {

                HttpSession session = WebContextFactory.get().getSession();

                String userId = ((Employee) session.getAttribute("loginuser")).getId();

                ev.getSession().setAttribute("userId", userId);

            }

            public void sessionDestroyed(ScriptSessionEvent ev) {

            }

        };

        manager.addScriptSessionListener(listener);

    }

}

新建MessagePush.java 初始化

public class MessagePush {

    public void onPageLoad(String userId) {

        ScriptSession scriptSession = WebContextFactory.get().getScriptSession();

        scriptSession.setAttribute(userId, userId);

        DwrScriptSessionManagerUtil dwrScriptSessionManagerUtil = new DwrScriptSessionManagerUtil();

        try {

               dwrScriptSessionManagerUtil.init();

        } catch (ServletException e) {

               e.printStackTrace();

        }

 }
}

最后我们在定义一个服务器发送消息的实体就行了

public class SendMessageAuto {

      public void sendMessageAuto(String userid,String message) {

          final String userId = userid ;

          final String autoMessage = 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() {
 			/* 前台接收的function 名为showMessage， 消息		         	是autoMessage */
                        script.appendCall("showMessage", autoMessage);

                        Collection<ScriptSession> sessions = Browser

                        .getTargetSessions();

                        for (ScriptSession scriptSession : sessions) {

                               scriptSession.addScript(script);

                        }

                 }

          });

   }
}

需要在接收页面上的js

<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/MessagePush.js"></script>

body 需要加入

<body onload="dwr.engine.setActiveReverseAjax(true);dwr.engine.setNotifyServerOnPageUnload(true);onPageLoad();">

加入js代码

/* dwr初始化 */
function onPageLoad(){
    var userId = '${loginuser.id}';
    MessagePush.onPageLoad(userId);

 }
/* dwr接收消息 */
function showMessage(autoMessage) {
    alertMsg.info(autoMessage);
}

客户端响应的是showMessage这个函数，这样我们就可以完成这个功能了。