Servlet的生命周期
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2022-03-11 21:58:48
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Servlet的生命周期
实例化---->初始化init()----->服务service()----->doGet/doPost方法------>销毁destory()
注意：实例化和初始化只执行一次
1. index.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<a href="WServlet">fdgadhbgb</a>
<form action="WServlet" method="get">
<input type="text" name="age">
<input type="submit">
</form>
<form action="WServlet" method="post">
<input type="text" name="age">
<input type="submit">
</form>
</body>
</html>
2.WServlet.java
package com.servlet;
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;
/**
* Servlet implementation class WServlet
*/
//@WebServlet("/WServlet")
public class WServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public WServlet() {
super();
// TODO Auto-generated constructor stub
System.out.println("===========实例化==========");
}
@Override
protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
// TODO Auto-generated method stub
System.out.println("===========service===========");
super.service(req, resp);
}
@Override
public void destroy() {
// TODO Auto-generated method stub
super.destroy();
System.out.println("=========destroy==========");
}
@Override
public void init() throws ServletException {
// TODO Auto-generated method stub
super.init();
System.out.println("==========init============");
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
System.out.println("========doGet========");
request.setCharacterEncoding("UTF-8");
response.setContentType("text/html;charset=utf-8");
PrintWriter out =response.getWriter();
out.println("doGet方法");
String age =request.getParameter("age");
out.println(age);
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
System.out.println("=======doPost========");
request.setCharacterEncoding("UTF-8");
response.setContentType("text/html;charset=utf-8");
PrintWriter out =response.getWriter();
out.println("doPost方法");
String age =request.getParameter("age");
out.println(age);
}
}
3. web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" id="WebApp_ID" version="3.1">
<display-name>Servlet123</display-name>
<welcome-file-list>
<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>WServlet</servlet-name>
<servlet-class>com.servlet.WServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>WServlet</servlet-name>
<url-pattern>/WServlet</url-pattern>
</servlet-mapping>
</web-app>4. 效果图
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