通过web.xml获取并输出ID，Name，Age

一.在web.xml中进行配置

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
         version="4.0">
    <context-param>
        <param-name>ID</param-name>
        <param-value>10</param-value>
    </context-param>
    <context-param>
        <param-name>Name</param-name>
        <param-value>zhangsan</param-value>
    </context-param>
    <context-param>
        <param-name>Age</param-name>
        <param-value>19</param-value>
    </context-param>
</web-app>

二.Java源码

import jakarta.servlet.ServletContext;
import jakarta.servlet.ServletException;
import jakarta.servlet.annotation.WebServlet;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.Enumeration;

@WebServlet("/demo1")
public class demo1 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doPost(req, resp);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        ServletContext servletContext = this.getServletContext();
        Enumeration<String> initParameterNames =servletContext.getInitParameterNames();
        while(initParameterNames.hasMoreElements()){
            String name =initParameterNames.nextElement();
            String initParameter=servletContext.getInitParameter(name);
            resp.getWriter().println(name+":"+initParameter);
        }
    }
}

三.运行截图