request对象学习
/*** request对象学习：* 作用：request对象中封存了当前请求的所有请求信息* 使用：* 获取请求头数据* req.getMethod();//获取请求方式* req.getRequestURL();//获取请求URL信息* req.getRequestURI();//获取请求URI信息* req.getScheme();//获取协议* 获取请求行数据* req.getHeader("键名");//返回指定的请求头信息* req.getHeaderNames();//返回请求头的键名的枚举集合* 获取用户数据* req.getParameter("键名");//返回指定的用户数据* req.getParameterValues("键名");//返回同键不同值的请求数据(多选)，返回的数组。* req.getParameterNames()//返回所有用户请求数据的枚举集合* 注意：* 如果要获取的请求数据不存在，不会报错，返回null。* * 注意：* request对象由tomcat服务器创建，并作为实参传递给处理请求的servlet的service方法。*/
method.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><form action="RequestServlet" method="post">用户名：<input type="text" name="uname" value=""><br>密码：<input type="text" name="pwd" value=""><br><input type="submit" value="登录" >爱好：<br /><input type="checkbox" name="fav" value="1"/>唱歌<br /><input type="checkbox" name="fav" value="2"/>跳舞<br /><input type="checkbox" name="fav" value="3"/>游泳<br /></form></body></html>
RequestServlet.java
package cn.hanquan.servlet;import java.io.IOException;import java.util.Enumeration;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;/*** Servlet implementation class RequestServlet*/public class RequestServlet extends HttpServlet {@Overrideprotected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {// 获取请求头数据// 获取请求方式// 输出String method = req.getMethod();System.out.println(method); // POST// 获取请求URLStringBuffer url = req.getRequestURL();System.out.println(url);// http://localhost:8080/01-MyServlet/RequestServlet// 获取URIString uri = req.getRequestURI();System.out.println(uri);// /01-MyServlet/RequestServlet// 获取协议String h = req.getScheme();System.out.println(h);// http// 获取请求行数据// 获取指定请求行信息String value = req.getHeader("User-Agent");System.out.println(value);// Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:68.0) Gecko/0101 Firefox/68.0// 获取所有请求行键枚举Enumeration e = req.getHeaderNames();while (e.hasMoreElements()) {String name = (String) e.nextElement();String value1 = req.getHeader(name);System.out.println(name + "：" + value1);}//输出://host：localhost:8080//user-agent：Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:68.0) Gecko/0101 Firefox/68.0//accept：text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8//accept-language：zh-CN,zh;q=0.8,zh-TW;q=0.7,zh-HK;q=0.5,en-US;q=0.3,en;q=0.2//accept-encoding：gzip, deflate//content-type：application/x-www-form-urlencoded//content-length：21//connection：keep-alive//referer：http://localhost:8080/01-MyServlet/method.jsp//cookie：JSESSIONID=0C3253D72B8F4F612E6500CB85FCAC46//upgrade-insecure-requests：1// 获取用户数据(用户提交的表单)String name = req.getParameter("uname");String pwd = req.getParameter("pwd");System.out.println(name + ":" + pwd);// xiaoming:123456String[] favs = req.getParameterValues("fav");if (favs != null) {for (String fav : favs) {System.out.println(fav);}}}}
