一、抛出问题
1.1 先看这么一段代码
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UserServlet.javapackage com.sunshine.servlet; import com.sunshine.entity.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; /** * @author 田港 * @version 1.0 * @date 2021-04-02 23:42 */ @WebServlet("/user") public class UserServlet extends HttpServlet { @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { List<User> userList = new ArrayList<>(); userList.add(new User(1, "张三", 78.6)); userList.add(new User(2, "李四", 79.6)); userList.add(new User(3, "王五", 80.2)); req.setAttribute("userList", userList); req.getRequestDispatcher("index.jsp").forward(req, resp); } } -
index.jsp<%-- Created by IntelliJ IDEA. User: Administrator Date: 2021-03-31 Time: 15:32 To change this template use File | Settings | File Templates. --%> <%@ page contentType="text/html;charset=UTF-8" language="java" %> <html> <head> <title>$Title$</title> </head> <body> <table> <tr> <th>编号</th> <th>姓名</th> <th>成绩</th> </tr> <tr> <td>${requestScope.userList[0].id}</td> <td>${requestScope.userList[0].name}</td> <td>${requestScope.userList[0].score}</td> </tr> <tr> <td>${requestScope.userList[1].id}</td> <td>${requestScope.userList[1].name}</td> <td>${requestScope.userList[1].score}</td> </tr> <tr> <td>${requestScope.userList[2].id}</td> <td>${requestScope.userList[2].name}</td> <td>${requestScope.userList[2].score}</td> </tr> </table> </body> </html>首先我们写了一段
Servlet代码，将 user 数据写到集合中，然后传递给 jsp 文件。那么问题来了，前端如果不知道你的集合有几个对象，那么怎么搞