javaweb-10：ServletContext对象

2022-03-16 19:45:52

6.5、ServletContext

web容器在启动的时候，它会为每个web程序都创建一个对应的ServletContext对象，它代表了当前的web应用

1.共享数据

我在这个Servlet中保存的数据，可以在另一个Servlet中拿到

核心代码：

HelloServlet.java

package com.gongyi.servlet;

import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

/**
 * @Classname HelloServlet
 * @Description TODO
 * @Date 2021/9/29 8:31
 * @Created by Administrator
 */
public class HelloServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //this.getInitParameter();//初始化参数
        //this.getServletConfig();//Servlet配置
        //this.getServletContext();//Servlet上下文
        ServletContext context = this.getServletContext();
        String userName = "工一";//数据
        context.setAttribute("userName",userName);//将一个数据保存在了Servlet中，名字为userName,值为userName


        System.out.println("Hello Servlet from servlet-02 module");
    }
}

GetServlet.java

package com.gongyi.servlet;

import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

/**
 * @Classname GetServlet
 * @Description TODO
 * @Date 2021/9/29 8:49
 * @Created by Administrator
 */
public class GetServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        ServletContext context = this.getServletContext();
        String userName = (String) context.getAttribute("userName");
        resp.setContentType("text/html");
        resp.setCharacterEncoding("utf-8");
        resp.getWriter().print("名字:"+userName);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req,resp);
    }
}

测试访问结果：