Request —— 获取请求行数据获取请求头数据获取请求体数据

1. request对象和response对象的原理
1. request和response对象是由服务器创建的。我们来使用它们
2. request对象是来获取请求消息，response对象是来设置响应消息

2. request对象继承体系结构：
   ServletRequest       --   接口
       |   继承
   HttpServletRequest   -- 接口
       |   实现
   org.apache.catalina.connector.RequestFacade 类(tomcat)

3. request功能：

1. 获取请求消息数据

1. 获取请求行数据
           * GET /day14/demo1?name=zhangsan HTTP/1.1
           * 方法：
               1. 获取请求方式：GET
                   * String getMethod()
               2. (*)获取虚拟目录：/day14
                   * String getContextPath()
               3. 获取Servlet路径: /demo1
                   * String getServletPath()
               4. 获取get方式请求参数：name=zhangsan
                   * String getQueryString()
               5. (*)获取请求URI：/day14/demo1
                   * String getRequestURI():       /day14/demo1
                   * StringBuffer getRequestURL() :http://localhost/day14/demo1

* URL:统一资源定位符： http://localhost/day14/demo1   中华人民共和国
                   * URI：统一资源标识符 : /day14/demo1                   共和国

               6. 获取协议及版本：HTTP/1.1
                   * String getProtocol()

7. 获取客户机的IP地址：
* String getRemoteAddr()

package cn.itcast.web.request;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 java.io.IOException;/*** 演示Request对象获取请求行数据*/@WebServlet("/requestDemo1")
public class RequestDemo1 extends HttpServlet {protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//1. 获取请求方式 ：GETString method = request.getMethod();System.out.println(method);//2.(*)获取虚拟目录：/day14String contextPath = request.getContextPath();System.out.println(contextPath);//3. 获取Servlet路径: /demo1String servletPath = request.getServletPath();System.out.println(servletPath);//4. 获取get方式请求参数：name=zhangsanString queryString = request.getQueryString();System.out.println(queryString);//5.(*)获取请求URI：/day14/demo1String requestURI = request.getRequestURI();StringBuffer requestURL = request.getRequestURL();System.out.println(requestURI);System.out.println(requestURL);//6. 获取协议及版本：HTTP/1.1String protocol = request.getProtocol();System.out.println(protocol);//7. 获取客户机的IP地址：String remoteAddr = request.getRemoteAddr();System.out.println(remoteAddr);}
}

2. 获取请求头数据
           * 方法：
               * (*)String getHeader(String name):通过请求头的名称获取请求头的值
               * Enumeration<String> getHeaderNames():获取所有的请求头名称

package cn.itcast.web.request;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 java.io.IOException;
import java.util.Enumeration;@WebServlet("/requestDemo2")
public class RequestDemo2 extends HttpServlet {protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//演示获取请求头数据//1.获取所有请求头名称Enumeration<String> headerNames = request.getHeaderNames();//2.遍历while(headerNames.hasMoreElements()){String name = headerNames.nextElement();//根据名称获取请求头的值String value = request.getHeader(name);System.out.println(name+"---"+value);}}
}

package cn.itcast.web.request;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 java.io.IOException;
import java.util.Enumeration;@WebServlet("/requestDemo3")
public class RequestDemo3 extends HttpServlet {protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//演示获取请求头数据:user-agentString agent = request.getHeader("user-agent");//判断agent的浏览器版本if(agent.contains("Chrome")){//谷歌System.out.println("谷歌来了...");}else if(agent.contains("Firefox")){//火狐System.out.println("火狐来了...");}}
}

package cn.itcast.web.request;import javax.servlet.ServletContext;
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 java.io.IOException;@WebServlet("/requestDemo4")
public class RequestDemo4 extends HttpServlet {protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//演示获取请求头数据:refererString referer = request.getHeader("referer");System.out.println(referer);//http://localhost/day14/login.html//防盗链if(referer != null ){if(referer.contains("dym_day14")){//正常访问// System.out.println("播放电影....");response.setContentType("text/html;charset=utf-8");response.getWriter().write("播放电影....");}else{//盗链//System.out.println("想看电影吗？来优酷吧...");response.setContentType("text/html;charset=utf-8");response.getWriter().write("想看电影吗？来优酷吧...");}}}
}

3. 获取请求体数据:
           * 请求体：只有POST请求方式，才有请求体，在请求体中封装了POST请求的请求参数
           * 步骤：
               1. 获取流对象
                   * BufferedReader getReader()：获取字符输入流，只能操作字符数据
                   * ServletInputStream getInputStream()：获取字节输入流，可以操作所有类型数

2. 再从流对象中拿数据

regist.html

<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>注册页面</title>
</head>
<body><form action="/dym_day14/requestDemo5" method="post"><input type="text" placeholder="请输入用户名" name="username"><br><input type="text" placeholder="请输入密码" name="password"><br><input type="submit" value="注册"></form></body>
</html>

RequestDemo5.java

package cn.itcast.web.request;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 java.io.BufferedReader;
import java.io.IOException;@WebServlet("/requestDemo5")
public class RequestDemo5 extends HttpServlet {protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//获取请求消息体--请求参数//1.获取字符流BufferedReader br = request.getReader();//2.读取数据String line = null;while((line = br.readLine()) != null){System.out.println(line);}}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {}
}