Servlet 上下文

package com.example.demo.learn.servlet.context;

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;

/**
 * 上下文的作用域，保存在服务器端, 不建议使用。
 * 多用户共享，类似全局变量
 */
@WebServlet("/ServletContextDemo")
public class ServletContextDemo extends HttpServlet{

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        // 重定向到另外一个servlet路径
        ServletContext servletContext = this.getServletContext();
        servletContext.setAttribute("name","song");
        servletContext.setAttribute("age",20);
    }
}

package com.example.demo.learn.servlet.context;

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("/ServletContextDemo2")
public class ServletContextDemo2 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        ServletContext servletContext = this.getServletContext();
        String name = (String) servletContext.getAttribute("name");
        Integer age = (Integer) servletContext.getAttribute("age");
        System.out.println(name + " >> " + age);
    }
}