1、HTTP简介

概念：超文本传输协议，规定了浏览器和服务器之间数据传输规则

HTTP协议特点：

1、基于TCP协议：面向连接，安全

2、 基于请求—响应模型的：一次请求对应一次响应

3、HTTP协议是无状态的协议：对于实物处理没有记忆能力。每次请求响应都是独立的

      缺点：多次请求间不能共享数据

      优点：速度快

 2、HTTP—请求数据格式

package first;
 
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Enumeration;
 
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
 
import org.apache.jasper.tagplugins.jstl.core.Out;
 
/**
 * Servlet implementation class Servlet01
 */
@WebServlet("/Servlet01")
public class Servlet01 extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public Servlet01() {
        super();
        // TODO Auto-generated constructor stub
    }
 
	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		//response.getWriter().append("Served at: ").append(request.getContextPath());
		String account=request.getParameter("account");
		String psd=request.getParameter("psd");
		PrintWriter out=response.getWriter();
		out.println(account);
		out.println(psd);
		Enumeration headers=request.getHeaderNames();
		response.setContentType("text/html;charset=utf_8");
		while(headers.hasMoreElements()) {
			String header_name=headers.nextElement();
			String header_value=request.getHeader(header_name);
			out.println("
"+header_name+":"+header_value+"h1");
		}
		out.println("
"+request.getRemoteAddr()+"
");
	}
 
	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		doGet(request, response);
	}
 
}

host:localhost:8080h1

connection:keep-aliveh1

content-length:19h1

cache-control:max-age=0h1

sec-ch-ua:"Microsoft Edge";v="105", " Not;A Brand";v="99", "Chromium";v="105"h1

sec-ch-ua-mobile:?0h1

sec-ch-ua-platform:"Windows"h1

upgrade-insecure-requests:1h1

origin:http://localhost:8080h1

content-type:application/x-www-form-urlencodedh1

user-agent:Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/105.0.0.0 Safari/537.36 Edg/105.0.1343.42h1

accept:text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9h1

sec-fetch-site:same-originh1

sec-fetch-mode:navigateh1

sec-fetch-user:?1h1

sec-fetch-dest:documenth1

referer:http://localhost:8080/Chapter1/firstJSP.jsph1

accept-encoding:gzip, deflate, brh1

accept-language:zh-CN,zh;q=0.9,en;q=0.8,en-GB;q=0.7,en-US;q=0.6h1

cookie:JSESSIONID=AD727F0589AD364C4C9ED5FF777CC4DFh1

0:0:0:0:0:0:0:1

 

请求数据的3部分：

1. 请求行：请求数据的第一行（get：请求方式，/表示请求资源路径，HTTP/1.1表示协议版本）
2. 请求头：第二行开始（格式为key：value形式）

       3. 请求体：POST请求的最后一部分（存放请求参数）

 

 GET请求和POST请求的区别：

1、GET：请求参数在请求行中，没有请求体

      POST：请求在请求体

2、GET请求：参数大小有限制

3、HTTP—响应数据格式

1、响应行：响应数据的第一行（HTTP/1.1表示协议版本，200表示响应状态码，OK表示状态码描述） 

2、响应头：第二行开始，（格式为key：value）

3、响应体：最后一部分（存放相应数据）

响应状态码: