httpServletRequest对象获取请求消息头

RequestDemo3.java 文件：

package com.neu;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;//获取请求消息头public class RequestDemo3 extends HttpServlet {    public void doGet(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        test3(request);    }    //得到所有的消息头    private void test3(HttpServletRequest request) {        Enumeration<String> e = request.getHeaderNames();        while(e.hasMoreElements()){            String headerName = e.nextElement();//透明称            Enumeration<String> headerValues = request.getHeaders(headerName);            while(headerValues.hasMoreElements()){                System.out.println(headerName+":"+headerValues.nextElement());            }        }    }    //http协议是允许头有重复的情况，多个重名的头    private void test2(HttpServletRequest request) {        Enumeration<String> e = request.getHeaders("Accept-Encoding");//得到的头值        while(e.hasMoreElements()){            String headerValue = e.nextElement();            System.out.println(headerValue);        }    }    //得到指定请求消息头的值。如果没有该头，返回null    private void test1(HttpServletRequest request) {        String supportEncoding = request.getHeader("Accept-Encoding");        if(supportEncoding.contains("gzip")){            System.out.println("支持gzip压缩");        }else{            System.out.println("不支持gzip压缩");        }    }    public void doPost(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        doGet(request, response);    }}

运行：http://localhost:8080/Request/servlet/RequestDemo3
结果：

• host:localhost:8080
  connection:keep-alive
  upgrade-insecure-requests:1
  user-agent:Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/51.0.2704.103 Safari/537.36
  accept:text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,/;q=0.8
  accept-encoding:gzip, deflate, sdch
  accept-language:zh-CN,zh;q=0.8