1)在web應用中，由服務器創建的唯一的一個對象是ServletContext
2)ServletContext對象在每一個Servlet中取得都是相同到
3)ServletContext對象在存取方法：
存ServletContext.setAttribute(String,Object):(返回值)void
取ServletContext.getAttribute(String):（返回值）Object

dome1

import java.io.IOException;
import java.io.PrintWriter;

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

public class contDome1 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        //取得客戶端的請求參數
        String nsername =   request.getParameter("username");
        //取得唯一的一個serverletContext對象
         ServletContext context =  this.getServletContext();

         //將信息存入ServletContext對象
         context.setAttribute("nsername", nsername);

    }

}
 

dome2

import java.io.IOException;
import java.io.PrintWriter;

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

public class contDome2 extends HttpServlet {

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

        //取得唯一的一個serverletContext對象
         ServletContext context =  this.getServletContext();

         //根據name取得ServletContext對象中的值
        String username =  (String) context.getAttribute("nsername");

        //在瀏覽器輸出
        response.setContentType("text/html;charset=UTF-8");
        response.getWriter().write("用戶名：" + username + "<br/>");

    }

}
 

瀏覽器訪問方式：

提交
http://localhost:8080/day04/contDome1？nsername=liwen

結果：
http://localhost:8080/day04/contDome2

ServletContext兩個Servlet傳值學習筆記