如何在.JSP文件中显示列表？ [英] How to display a list in a .JSP file?
问题描述
经过一个小时的坚实研究后，我仍然无法做到这一点。
After an hour of solid research I still can't do this.
这是我的Servlet代码：
This is my Servlet code:
package com.fdm.ProjectWeb.RedirectServlets;
import java.awt.List;
import java.io.IOException;
import java.sql.ResultSet;
import java.sql.SQLException;
import javax.naming.spi.DirStateFactory.Result;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.jsp.jstl.sql.ResultSupport;
import com.fdm.ProjectWeb.Controller.ValidateRegisterInputController;
import com.fdm.ProjectWeb.Model.OraclePullListOfUsers;
import com.fdm.ProjectWeb.Model.OracleUserManagement;
public class VerifyRedirect extends HttpServlet {
private static final long serialVersionUID = 1L;
public void doPost(HttpServletRequest req, HttpServletResponse resp) throws IOException, ServletException{
OraclePullListOfUsers pull = new OraclePullListOfUsers();
ResultSet rs = pull.unverifiedUsers();
List list = new List();
try {
while (rs.next()){
list.add(rs.getString(1));
}
} catch (SQLException e) {
e.printStackTrace();
}
req.setAttribute("list", list);
RequestDispatcher rd = req.getRequestDispatcher("./WEB-INF/VerifyUser.jsp");
rd.forward(req, resp);
}
}
这是我的.JSP代码：
And this is my .JSP code:
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<html>
<head>
<title>Verify Users</title>
</head>
<body>
<table>
<c:forEach items="${list}" var="item">
<tr>
<td><c:out value="${item}" /></td>
</tr>
</c:forEach>
</table>
<h2>Please enter the Username of the user you want to verify</h2>
<form action="loginform" method="POST">
<label>User To Verify: <input type="text" name="userToVerify" id="userToVerify" /></label><br />
<input type="submit" value="Submit" name="submit" />
</form>
</body>
结果集中肯定有数据，就像我在while循环中的system.out.println一样显示所有正确的值。
The Result Set definitely has data in it as if I system.out.println in the while loop it shows all the right values.
我收到此错误消息：
javax.servlet.jsp.JspTagException: Don't know how to iterate over supplied "items" in <forEach>
任何帮助都将不胜感激！
Any help would be appreciated!
推荐答案
javax.servlet.jsp.JspTagException：不知道如何迭代< forEach>中提供的items
javax.servlet.jsp.JspTagException: Don't know how to iterate over supplied "items" in <forEach>
当< c：forEach items> 未引用 Object <时，会发生此异常/ em>，可以迭代。 Object 应为 Iterable ， Map 或数组。
很明显，您的列表属性是指不属于上述任何类别的类型。虽然类型实际上是 List ，但不是 java.util.List 。
This exception occur when your <c:forEach items> does not refer to an Object, that can be iterated upon. The Object should either be Iterable, a Map, or an array.
So clearly, your list attribute refers to the type which does not come under any of the above category. Though the type is actually a List, but not java.util.List.
检查您的import语句：
Check your import statement:
import java.awt.List; // Here is the fault
它应该是：
import java.util.List;
此外，您应该使用泛型类型列表而不是原始类型。更改：
Also, you should use generic type List instead of raw type. Change:
List list = new List();
to：
List<String> list = new List<String>();
此外，您好像在做 c> doPost（）方法中的预处理任务。别。 doPost（）用于后期处理 a申请。您应该使用 doget（）方法进行预处理。
Also, it seems like you are doing the pre-processing task in doPost() method. Don't. doPost() is used for post-processing a request. You should use doget() method for pre-processing.
移动所有你的代码在 doPost（）到 doGet（）方法。
Move all your code in doPost() to doGet() method.
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