共有データ要求（ドメインオブジェクト）

データを共有：

* 域对象：一个有作用范围的对象，可以在范围内共享数据
* request域：代表一次请求的范围，一次请求访问多个资源，即转发，一般用于请求转发的多个资源中共享数据
* 方法：
	1. void setAttribute(String name,Object obj):存储数据
	2. Object getAttitude(String name):通过键获取值
	3. void removeAttribute(String name):通过键移除键值对

requestDemo7とrequestDemo9データ共有：

package com.web.request;

import javax.servlet.RequestDispatcher;
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;

/**
 * @ClassName: ${NAME}
 * @Description: TODO
 * @author: Doge_fang
 * @date: 2020/3/3  21:25
 */
@WebServlet("/requestDemo7")
public class RequestDemo7 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //System.out.println("requestDemo7 is ok ....");

        //转发之前存储数据到request域中
        request.setAttribute("name","zhangsan");
        //转发到demo8资源,将request,response对象传过去
        request.getRequestDispatcher("/requestDemo9").forward(request,response);

    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doPost(request,response);

    }
}

package com.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;

/**
 * @ClassName: ${NAME}
 * @Description: TODO
 * @author: Doge_fang
 * @date: 2020/3/3  21:26
 */
@WebServlet("/requestDemo9")
public class RequestDemo9 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //获取数据
        Object msg = request.getAttribute("name");
        System.out.println(msg);


    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doPost(request,response);

    }
}