java Web 学习10：Servlet学习

一、创建Servlet项目

1、编写web.xml文件

<?xml version="1.0" encoding="UTF-8"?>
<web-app 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_4_0.xsd"
         version="4.0">
    <servlet>
        <servlet-name>ServletHelloServletWorld</servlet-name>
        <servlet-class>net.qing.servlet.ServletHelloServletWorld</servlet-class>
        <init-param>
            <param-name>username</param-name>
            <param-value>qing</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>ServletHelloServletWorld</servlet-name>
        <url-pattern>/hello</url-pattern>
    </servlet-mapping>

</web-app>

2、编写首页文件
在这里插入图片描述
3、Servlet模板创建HelloServletWorld类

package net.qing.servlet;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebInitParam;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;
import java.text.SimpleDateFormat;
import java.util.Date;

@WebServlet(name = "ServletHelloServletWorld",
            value = "/hello",
            initParams = {
        @WebInitParam(name = "username",value = "qing")
            },
        loadOnStartup = 1)
public class ServletHelloServletWorld extends HttpServlet {
    //添加init（）方法
    @Override
    public void init() throws ServletException{
        super.init();
        System.out.println("初始化servlet....");
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doGet(request,response);

    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        //设置编码字符
        response.setCharacterEncoding("utf-8");
        //获取初始化参数值
        String username = getInitParameter("username");
        //获取打印输出流
        PrintWriter out = response.getWriter();
        //创建简单日期格式对象
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy年MM月dd日 hh:mm:ss");
        //向客户端输出信息
        out.print("<html>"+
                "<head>"+
                "<meta charset='UTF-8'>"+
                "<title>亲切地问好</title>"+
                "</head>"+
                "<body>"+
                "<h3>亲爱的"+username+"，欢迎访问Serlet世界</h3>"+
                "<h3>当前时间："+sdf.format(new Date()) + "</h3>"+
                "</body>"+
                "</html>");

    }
    //添加destroy()
    @Override
    public void destroy(){
        super.destroy();
        System.out.println("销毁serlet.....");

    }
}