HttpServletRequest介绍和使用

基本介绍

httpServletRequest对象对http请求进行了封装，我们使用这个对象就可以方便快捷的获取http中的信息。HttpServletRequest 对象代表客户端的请求，在里面就包含了所有的客服端信息，我们通过这个对象的方法便可以获取所有的客服端信息，包括请求头和请求体中的所有数据。

常见方法

getRequestURL()：得到请求的URI
getRequestURL()：得到请求的URL
getHeader(String s)：getHeader表示得到请求头，参数s表示想要获取请求头中的什么数据
getHeader(“Host”)：获取请求的主机
getHeader(“Referer”)：获取请求来自于哪里，一般用来做防盗链
getRemotetAddr()：得到请求的ip
getParameter(String s)：得到请求参数的值
getParameterValues(String s)：得到请求参数的值，用于参数有多个值，返回一个数组

方法演示

我们创建一个注册页面来提交数据，服务器将获取数据并进行展示，代码如下

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>登录</title>
</head>
<body>
<form action="http://localhost:8080/servlet/requestTest" method="post">
    用户名:<input type="text" name="username"> <br>
    密　码:<input type="password" name="password"><br>
    爱好 <input type="checkbox" name="hobby" value="lq">篮球
    <input type="checkbox" name="hobby" value="zq">足球
    <input type="checkbox" name="hobby" value="pq">排球<br>
    <input type="submit" value="注册">
</form>
</body>
</html>

import javax.servlet.*;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.*;
import java.io.IOException;
import java.util.Arrays;

@WebServlet("/requestTest")
public class HttpServletRequestTest extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //得到请求URL
        StringBuffer requestURL = request.getRequestURL();
        System.out.println("请求的URL是：" + requestURL);
        //得到请求URI
        String requestURI = request.getRequestURI();
        System.out.println("请求的URI是：" + requestURI);
        //得到主机名Host
        String host = request.getHeader("Host");
        System.out.println("请求的主机名是：" + host);
        //得到请求的ip
        String ip = request.getRemoteAddr();
        System.out.println(ip);
        //得到请求参数，分别得到用户名，密码还有爱好
        //如果参数中有中文，需要设置编码
        request.setCharacterEncoding("utf-8");
        String username = request.getParameter("username");
        String password = request.getParameter("password");
        String[] hobbies = request.getParameterValues("hobby");
        System.out.println("用户名为：" + username);
        System.out.println("密码：" + password);
        System.out.println("爱好为：" + Arrays.toString(hobbies));
        //得到访问来自哪里
        String referer = request.getHeader("Referer");
        System.out.println("请求来自于：" + referer);
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doGet(request, response);
    }
}

下面是我们提交的数据

抓包进行查看

请求头

POST /servlet/requestTest HTTP/1.1
Host: localhost:8080
Connection: keep-alive
Content-Length: 60
Cache-Control: max-age=0
sec-ch-ua: " Not A;Brand";v="99", "Chromium";v="98", "Google Chrome";v="98"
sec-ch-ua-mobile: ?0
sec-ch-ua-platform: "Windows"
Upgrade-Insecure-Requests: 1
Origin: http://localhost:8080
Content-Type: application/x-www-form-urlencoded
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/98.0.4758.102 Safari/537.36
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9
Sec-Fetch-Site: same-origin
Sec-Fetch-Mode: navigate
Sec-Fetch-User: ?1
Sec-Fetch-Dest: document
Referer: http://localhost:8080/servlet/register_request.html
Accept-Encoding: gzip, deflate, br
Accept-Language: zh-CN,zh;q=0.9
Cookie: JSESSIONID=ABEC5EA43080A0BFA70C2AABDF39BB7C; Pycharm-cb145b54=bac13d99-2d7f-4b5f-9c85-e783571ee72d; Idea-8cd34e8b=1bf6d6e0-14ee-4950-96ec-48105743bb40

请求体