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 *
* URI：统一资源标识符 : /day14/demo1 *
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()
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 getHeaderNames():获取所有的请求头名称

package ypy.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;

@WebServlet("/requestDemo1")
public class RequestDemo1 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        /**
         * 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	*
         * 						* URI：统一资源标识符 : /day14/demo1					*
         * 					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()
         */
        String method = req.getMethod();
        System.out.println(method);
        String contestPath = req.getContextPath();
        System.out.println(contestPath);
        String servletPath = req.getServletPath();
        System.out.println(servletPath);
        String getQueryString = req.getQueryString();
        System.out.println(getQueryString);
        String getRequestURI = req.getRequestURI();
        System.out.println(getRequestURI);
        StringBuffer getRequestURL = req.getRequestURL();
        System.out.println(getRequestURL);
        String protocol = req.getProtocol();
        System.out.println(protocol);
        String remote = req.getRemoteAddr();
        System.out.println(remote);
        String agent = req.getHeader("user-agent");
        System.out.println(agent);
        if(agent.contains("Chrome")){
            System.out.println("Google");
        }else{
            System.out.println("其他浏览器");
        }
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        super.doPost(req, resp);
    }
}

运行结果：