ServletContext对于信息的存储和共享

ServletContext的使用需要多个对象，任何一个对象传输数据后，其余的对象都可以取用改数据

HelloServlet传输一个名字

package com.su.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;
import java.io.PrintWriter;
import java.nio.charset.StandardCharsets;

public class HelloServlet extends HttpServlet {
    //由于get和post知识请求实现的不同方式,谁调用谁都一样
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

//        this.getServletConfig();  servlet配置
//        this.getInitParameter();   初始化参数
//        this.getServletContext();   servlet上下文

        resp.setContentType("text/html");
        resp.setCharacterEncoding("utf-8");
        ServletContext servletContext = this.getServletContext();
        String name="苏";
        servletContext.setAttribute("username",name);
        //将一个数据保存在ServletContext中，名字为ServletContext,名字为username,值rname
        PrintWriter writer = resp.getWriter();
        writer.print("名字是"+name);
    }

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

GetName用来获取别的ServletContext对象传输的数据

package com.su.servlet;

import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;
import java.io.IOException;

@WebServlet(name = "Servlet", value = "/Servlet")
public class GetName extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //解决中文乱码设置格式
        response.setContentType("text/html");
        response.setCharacterEncoding("utf-8");


        ServletContext context = this.getServletContext();
        String n = (String) context.getAttribute("username");
        response.getWriter().print("名字是"+n);
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    }
}

配置两个Servlet的web.xml文件：

    
        hello
        com.su.servlet.HelloServlet
    

    
        hello
        /hello
    

    
    
        get
        com.su.servlet.GetName
    

    
        get
        /get
    

运行结果如下：

使用HelloServlet存入数据 

使用GetName取出数据