ServletContext两个Servlet传值学习笔记

Posted 2020-10-31

ServletContext对象

1)在web应用中，由服务器创建的唯一的一个对象是ServletContext
2)ServletContext对象在每一个Servlet中取得都是相同到
3)ServletContext对象在存取方法：
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 {
        //取得客户端的请求参数
        String nsername =   request.getParameter("username");
        //取得唯一的一个serverletContext对象
         ServletContext context =  this.getServletContext();

         //将信息存入ServletContext对象
         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 {

        //取得唯一的一个serverletContext对象
         ServletContext context =  this.getServletContext();

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

        //在浏览器输出
        response.setContentType("text/html;charset=UTF-8");
        response.getWriter().write("用户名：" + username + "<br/>");

    }

}

浏览器访问方式：

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

结果：
http://localhost:8080/day04/contDome2