03.域对象概念的讲解

 

package com.gyf.web.servlet.lesson03;

import java.io.IOException;
import java.util.Arrays;

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


@WebServlet("/Lesson3Servlet1")
public class Lesson3Servlet1 extends HttpServlet {
   
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        
        /**
         * 数据的存储方式:
         * 1.ServletContext【application】 在整个应用是共享:范围最大
         * 2.Session 在同一个浏览器同一个Session才有效
         * 3.request 在同一个请求对象中有效【转发】
         */
        //this.getServletContext().setAttribute("name", "gyf");
        //request.getSession().setAttribute("name", "gyf");
        request.setAttribute("name", "gyf");
        request.getRequestDispatcher("/Lesson3Servlet2").forward(request, response);
    
    }

}

 

package com.gyf.web.servlet.lesson03;

import java.io.IOException;
import java.util.Arrays;

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


@WebServlet("/Lesson3Servlet2")
public class Lesson3Servlet2 extends HttpServlet {
   
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        
        //取值
        //String name = (String) this.getServletContext().getAttribute("name");
        //String name = (String) request.getSession().getAttribute("name");
        String name = (String) request.getAttribute("name");
        
        response.getWriter().write(name);
    
    }

}