ServletContext-概述、获取

ServletContext概述

　　1.概念：代表整个web应用，可以和程序的容器（服务器）来通信

　　2.获取：

　　　　1.通过request对象获取

　　　　　　request.getServletContext();

　　　　2.通过HttpServlet获取

　　　　　　this.getServletContext()

　　3.功能

　　　　1.获取MIME类型

　　　　2.域对象：共享数据

　　　　3.获取文件的真实（服务器）路径

ServletContext获取

package com.example.servletcontext;

import javax.servlet.ServletContext;
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("/servletContextDemo1")
public class ServletContextDemo1 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        /*

            ServletContext对象获取：
                1. 通过request对象获取
                    request.getServletContext();
                2. 通过HttpServlet获取
                    this.getServletContext();
         */
        
        //1. 通过request对象获取
        ServletContext context1 = request.getServletContext();
        //2. 通过HttpServlet获取
        ServletContext context2 = this.getServletContext();

        System.out.println(context1);
        System.out.println(context2);

        System.out.println(context1 == context2);//true


    }

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