request应用-请求头学习笔记

Posted 2020-10-31

request对象常用API

1）取得请求头相关的信息
*a)request.getHeader(String):String
b)request.getHeaders(String):Enumeration
c)getHeaderNames():Enumeration

java代码实现：

import java.io.IOException;
import java.io.PrintWriter;
import java.util.Enumeration;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class Rdome2 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

        response.setCharacterEncoding("utf-8");
        //客户端接收的语言类型
        String acceptLanguage = response.getHeader("Accept-Language");
        //客户端版本号的名字
        String userAgent = request.getHeader("User-Agent");
        //连接的目标主机和端口号
        String host = request.getHeader("Host");
        response.getWriter().write("客户端接收的语言类型 Accept-Language=" + acceptLanguage + "<br/>");
        response.getWriter().write("客户端版本号的名字 User-Agent=" + userAgent + "<br/>");
        response.getWriter().write("连接的目标主机和端口号 Host=" + host + "<br/>");
        response.getWriter().write("========================================= "+ "<br/>");
        //一次性取得所有的请求头信息
        Enumeration<String> enums  = request.getHeaderNames();
        while(enums.hasMoreElements())
        {
            //请求头
            String keys =  enums.nextElement();
            Enumeration<String> enums2 = request.getHeaders(keys);
            while(enums2.hasMoreElements())
            {
                String value = enums2.nextElement();
                response.getWriter().write(keys+"<->"+value+"<br/>");
            }

        }

    }

}