代码部分很简单,只需要新建一个serlet,继承自HttpServlet,重写init,doGet,doPost,destory方法即可,使用注解@WebServlet注解分别测试存在loadOnStartup 和不存在loadOnStartup情况
package com.demo; import java.io.IOException; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; @WebServlet(value = "/my", loadOnStartup = 0) public class MyServlet extends HttpServlet { public MyServlet() { System.out.println("create"); } @Override public void init() throws ServletException { System.out.println("init"); } @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { doPost(req, resp); } @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { System.out.println("service"); } @Override public void destroy() { System.out.println("destory"); } }
一、当配置有loadOnStartup且值大于等于0时,web服务器启动即会创建和初始化该servlet,且loadOnStartup数值越小,越优先执行,后续每次访问该servlet,将会调用一次service服务(doGet/doPost),关闭web服务,调用destory方法,销毁servlet
二、当未配置loadOnStartup时,web服务器启动时不会初始化该servlet,当第一次访问该servlet时,才会进行创建并初始化,后续每次访问该servlet,都将会调用一次service服务(doGet/doPost),关闭web服务,调用destory方法,销毁servlet。