吴裕雄--天生自然JAVA开发JSP-Servlet学习笔记：servlet服务-load-on-startup Servlet

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import javax.servlet.http.*;
import javax.servlet.*;
import javax.servlet.annotation.*;

import javax.swing.*;
import java.awt.event.*;
import java.util.Date;

/**
 *
 * @author Administrator
 */
@WebServlet(loadOnStartup = 1)
public class TimerServlet extends HttpServlet {

    public void init(ServletConfig config) throws ServletException {
        super.init(config);
        Timer t = new Timer(1000, new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                System.out.println(new Date());
            }
        });
        t.start();
    }
}

<?xml version="1.0" encoding="UTF-8"?>
<web-app metadata-complete="true" version="3.1" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee                       http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd">
    <!-- 配置Servlet的名字 -->
    <servlet>
        <!-- 指定Servlet的名字，
        相当于指定@WebServlet的name属性 -->
        <servlet-name>firstServlet</servlet-name>
        <!-- 指定Servlet的实现类 -->
        <servlet-class>FirstServlet</servlet-class>
    </servlet>
    <!-- 配置Servlet的URL -->
    <servlet-mapping>
        <!-- 指定Servlet的名字 -->
        <servlet-name>firstServlet</servlet-name>
        <!-- 指定Servlet映射的URL地址，
        相当于指定@WebServlet的urlPatterns属性-->
        <url-pattern>/aa</url-pattern>
    </servlet-mapping>
    <servlet>
        <!-- Servlet名 -->
        <servlet-name>timerServlet</servlet-name>
        <!-- Servlet的实现类 -->
        <servlet-class>TimerServlet</servlet-class>
        <!-- 配置应用启动时，创建Servlet实例
        ，相当于指定@WebServlet的loadOnStartup属性-->
        <load-on-startup>1</load-on-startup>
    </servlet>
    <welcome-file-list>
        <welcome-file>index.html</welcome-file>
        <welcome-file>index.htm</welcome-file>
        <welcome-file>index.jsp</welcome-file>
    </welcome-file-list>
</web-app>