Javaweb基础复习------EL表达式+JSTL-if&foreach

EL表达式------简化JSP页面的Java代码

主要功能是------获取数据（语法：${data}）

举例：

//ServletDemo1.java
package com.example.servlet;

import com.example.pojo.User;

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;
import java.util.ArrayList;
import java.util.List;

@WebServlet("/ServletDemo1")
public class ServletDemo1 extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //1、准备数据
        List<User> user=new ArrayList<User>();
        user.add(new User(1,2,3,"q"));
        user.add(new User(2,3,4,"w"));
        user.add(new User(3,4,5,"e"));

        req.setAttribute("user",user);

        req.getRequestDispatcher("demo1.jsp").forward(req,resp);

    }

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

//demo1.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>EL</title>
</head>
<body>
${user}
</body>
</html>