Unit01： Servlet基础 HTTP协议

Posted 2020-08-31 唐胜伟

　　　　Unit01： Servlet基础 、 HTTP协议　　　　

在页面上输出当前时间

package web;

import java.io.IOException;
import java.io.PrintWriter;
import java.text.SimpleDateFormat;
import java.util.Date;

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

public class TimeServlet extends HttpServlet {

    @Override
    protected void service(
        HttpServletRequest req, 
        HttpServletResponse res) throws ServletException, IOException {
        //1.使用request接收请求数据
        //1.1请求行
        System.out.println(
            "请求方式:"+req.getMethod());
        System.out.println(
            "访问路径:"+req.getServletPath());
        System.out.println(
            "协议类型:"+req.getProtocol());
        //1.2消息头
        //1.3实体内容
        
        //2.使用response发送响应数据
        
        //获取服务器时间
        Date date = new Date();
        SimpleDateFormat sdf = 
            new SimpleDateFormat("HH:mm:ss");
        String now = sdf.format(date);
        //告诉浏览器发送给它的是网页
        res.setContentType("text/html");
        //获取writer
        PrintWriter out = res.getWriter();
        //输出网页的内容(偷懒少写点)
        out.println("<p>"+now+"</p>");
        //关闭writer
        out.close();
    }

}

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" version="2.5">
  <display-name>servlet1</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>
  
  <!-- 1.给Servlet取一个别名 -->
  <servlet>
      <servlet-name>time</servlet-name>
      <servlet-class>web.TimeServlet</servlet-class>
  </servlet>
  <!-- 2.给Servlet取一个网络访问路径(网名) -->
  <servlet-mapping>
      <servlet-name>time</servlet-name>
      <url-pattern>/ts</url-pattern>
  </servlet-mapping>
  
</web-app>

web.xml