Question

我正在开发一个J2EE项目，简而言之就是在指定时间向用户发送自动电子邮件，并允许用户从通过电子邮件发送给他们的网页下载文件。它运作得很好。

但是，我使用@Schedule注释的计时器方法被调用两次。该方法总是在运行时立即执行（我不想要），然后在指定的时间执行。我已经包含了部署应用程序时加载的Servlet代码，Schedule类和我的web.xml文件。

    package downloadsupport;

    import java.io.IOException;
    import java.io.PrintWriter;

    import javax.servlet.ServletException;
    import javax.servlet.annotation.WebServlet;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;

    import scheduleTimer.ScheduleEmail;

    /**
     * Servlet implementation class InitializeApplicationServlet
     */
    @WebServlet("/DeployApplicationServlet")
    public class DeployApplicationServlet extends HttpServlet {
        private static final long serialVersionUID = 1L;

        /**
         * @see HttpServlet#HttpServlet()
         */
        public DeployApplicationServlet() {
           super();
        }

        /**
         * @see HttpServlet#doGet(HttpServletRequest request,
        HttpServletResponse response)
         */
        protected void doGet(HttpServletRequest request, HttpServletResponse
        response) throws ServletException, IOException {
            PrintWriter out = response.getWriter();
            out.println("Web Application Started");

            ScheduleEmail se = new ScheduleEmail();
            se.sendAutomatedEmail();
        }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    }

}




    package scheduleTimer;

    import java.util.Date;

    import javax.ejb.Schedule;
    import javax.ejb.Stateless;

    import java.net.*;
    import java.io.*;


    @Stateless
    public class ScheduleEmail {

        @Schedule(second = "0", minute = "10", hour = "12", dayOfWeek = "Wed")
        public void sendAutomatedEmail() {
            // Print Time to console for testing purposes
            System.out.println(new Date());

            // Invoke the SendEmailServlet at the designated time
            try {
            URL emailServlet = new
              URL("http://localhost:9081/downloadsupport/SendEmailServlet");
              URLConnection servletConn = emailServlet.openConnection();
            BufferedReader in = new BufferedReader(new InputStreamReader(
                servletConn.getInputStream()));
            String inputLine;

            while ((inputLine = in.readLine()) != null)
                System.out.println(inputLine);
                in.close();
            }
            catch (Exception e) {
                e.printStackTrace();
            }
        }
    }

    <?xml version="1.0" encoding="UTF-8"?>
    <web-app id="WebApp_ID" version="3.0" 
    xmlns="http://java.sun.com/xml/ns/javaee"   
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee   
    http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">
        <display-name>downloadsupport</display-name>

        <servlet>
            <servlet-name>SendEmailServlet</servlet-name>
            <servlet-class>downloadsupport.SendEmailServlet</servlet-class>
        </servlet>

        <servlet>
            <servlet-name>DeployApplicationServlet</servlet-name>
            <servlet-class>downloadsupport.DeployApplicationServlet</servlet- 
             class>
        </servlet>

        <welcome-file-list>
            <welcome-file>DeployApplicationServlet</welcome-file>
            <!--  <welcome-file>SendEmailServlet</welcome-file> -->
            <welcome-file>index.html</welcome-file>
            <welcome-file>index.htm</welcome-file>
            <welcome-file>index.jsp</welcome-file> 
            <welcome-file>default.html</welcome-file>
            <welcome-file>default.htm</welcome-file>
            <welcome-file>default.jsp</welcome-file>
    </welcome-file-list>

    <servlet>
        <servlet-name>DownloadServet</servlet-name>
        <servlet-class>downloadsupport.DownloadServlet</servlet-class>
    </servlet>

     <!--
     <servlet-mapping>
        <servlet-name>DownloadServlet</servlet-name>
        <url-pattern>/downloadServlet</url-pattern>
    </servlet-mapping>   
     -->
    </web-app>

Answer 1

您的第一个不必要的电话是由您引起的，而不是由不工作的服务器引起的。

您不需要实例化ScheduleEmail。从servlet中删除这两行，它将正常工作。

Container负责初始化bean并调用标有@Schedule

的方法

Answer 2

检查您的服务器实例。如果服务器中有2个节点。然后将其设置为比ejb计时器将按预期工作的一个节点。

Java EJB @Schedule注释方法被调用两次

2 个答案: