为什么我写的和老师的代码一样，页面却不显示数据呢，
来源：3-4 列表显示页面跳转的代码实现
qq_慕UI0173712
2019-08-16 13:40:22
这是category_list.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<!DOCTYPE html>
<html>
<!-- Mirrored from admindesigns.com/demos/absolute/1.1/admin_forms-validation.html by HTTrack Website Copier/3.x [XR&CO'2014], Thu, 06 Aug 2015 02:56:15 GMT -->
<head>
<!-- Meta, title, CSS, favicons, etc. -->
<meta charset="utf-8">
<title> 商城--分类列表 </title>
<link rel="stylesheet" type="text/css" href="${pageContext.request.contextPath }/assets/skin/default_skin/css/theme.css">
<link rel="stylesheet" type="text/css" href="${pageContext.request.contextPath }/assets/admin-tools/admin-forms/css/admin-forms.css">
<link rel="shortcut icon" href="${pageContext.request.contextPath }/assets/img/favicon.ico">
</head>
<body class="admin-validation-page" data-spy="scroll" data-target="#nav-spy" data-offset="200">
<div id="main">
<%@ include file="header.jsp" %>
<%@ include file="left.jsp" %>
<section id="content_wrapper">
<section id="content" class="table-layout animated fadeIn">
<div class="tray tray-center">
<div class="content-header">
<h2> 分类列表 </h2>
<p class="lead"></p>
</div>
<div class="admin-form theme-primary mw1000 center-block" style="padding-bottom: 175px;">
<div class="panel heading-border">
<div class="panel-menu">
<div class="row">
<div class="hidden-xs hidden-sm col-md-3">
<div class="btn-group">
<button type="button" class="btn btn-default light">
<i class="fa fa-refresh"></i>
</button>
<button type="button" class="btn btn-default light">
<i class="fa fa-trash"></i>
</button>
<button type="button" class="btn btn-default light">
<i class="fa fa-plus" onclick="javascript:window.location.href='/employee/to_add';"></i>
</button>
</div>
</div>
<div class="col-xs-12 col-md-9 text-right">
<div class="btn-group">
<button type="button" class="btn btn-default light">
<i class="fa fa-chevron-left"></i>
</button>
<button type="button" class="btn btn-default light">
<i class="fa fa-chevron-right"></i>
</button>
</div>
</div>
</div>
</div>
<div class="panel-body pn">
<table id="message-table" class="table admin-form theme-warning tc-checkbox-1">
<thead>
<tr class="">
<th class="hidden-xs">名称</th>
<th class="hidden-xs">描述</th>
<th>操作</th>
</tr>
</thead>
<tbody>
<c:forEach var=" category " items="${list }">
<tr class="message-unread">
<td>${category.cname }</td>
<td>${category.cdesc}</td>
<td>
<a href="#">编辑</a>
<a href="#">删除</a>
</td>
</tr>
</c:forEach>
</tbody>
</table>
</div>
</div>
</div>
</div>
</section>
</section>
</div>
<style>
/* demo page styles */
body { min-height: 2300px; }
.content-header b,
.admin-form .panel.heading-border:before,
.admin-form .panel .heading-border:before {
transition: all 0.7s ease;
}
/* responsive demo styles */
@media (max-width: 800px) {
.admin-form .panel-body { padding: 18px 12px; }
}
</style>
<style>
.ui-datepicker select.ui-datepicker-month,
.ui-datepicker select.ui-datepicker-year {
width: 48%;
margin-top: 0;
margin-bottom: 0;
line-height: 25px;
text-indent: 3px;
color: #888;
border-color: #DDD;
background-color: #FDFDFD;
-webkit-appearance: none; /*Optionally disable dropdown arrow*/
}
</style>
<script src=" ${pageContext.request.contextPath } /vendor/jquery/jquery-1.11.1.min.js"></script>
<script src=" ${pageContext.request.contextPath } /vendor/jquery/jquery_ui/jquery-ui.min.js"></script>
<script src=" ${pageContext.request.contextPath }/ assets/admin-tools/admin-forms/js/jquery.validate.min.js"></script>
<script src=" ${pageContext.request.contextPath } /assets/admin-tools/admin-forms/js/additional-methods.min.js"></script>
<script src=" ${pageContext.request.contextPath } /assets/admin-tools/admin-forms/js/jquery-ui-datepicker.min.js"></script>
<script src=" ${pageContext.request.contextPath }/ assets/js/utility/utility.js"></script>
<script src=" ${pageContext.request.contextPath } /assets/js/demo/demo.js"></script>
<script src=" ${pageContext.request.contextPath }/ assets/js/main.js"></script>
<script type="text/javascript" src=" ${pageContext.request.contextPath } /js/pages.js"></script>
<script type="text/javascript" src=" ${pageContext.request.contextPath } /js/items.js"></script>
</body>
</html>这是CategoryDaoImpl.java
package com.winking.dao.impl;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.ArrayList;
import java.util.List;
import com.winking.dao.CategoryDao;
import com.winking.domain.Category;
import com.winking.utils.JDBCUtils;
public class CategoryDaoImpl implements CategoryDao {
@Override
public List<Category> findAll() {
System.out.println("CategoryDao的findAll方法执行了...");
Connection conn =null;
PreparedStatement pstmt=null;
ResultSet rs=null;
List<Category> list = null;
try {
//1.获得连接
conn=JDBCUtils.getConnection();
//2.编写SQL
String sql ="select * from category";
//3.预编译SQL
pstmt= conn.prepareStatement(sql);
//4.设置参数
//5.执行SQL
rs=pstmt.executeQuery();
//6.结果处理
list= new ArrayList<Category>();
while(rs.next()) {
Category category= new Category();
category.setCid(rs.getInt("cid"));
category.setCname(rs.getString("cname"));
category.setCdesc(rs.getString("cdes"));
list.add(category);
}
}catch(Exception e) {
e.printStackTrace();
}finally {
//7.释放资源
JDBCUtils.release(rs, pstmt,conn);
}
return list;
}
}写回答
3回答
-
同学你好！
同学这里var后面的空格也会被定义为这个变量的名字里面，这样变量的名字就是：
空格+category+空格。所以通过category就获取不到值了，同学将前后的空格去掉就可以了
如果我的回答解决了你的疑惑，请采纳，祝学习愉快~
0 -
qq_慕UI0173712
提问者
2019-08-16
0 -
好帮手慕柯南
2019-08-16
同学你好！
数据库中有数据吗？
是否将查询到的数据返回页面
idea或者浏览器的控制台是否报错。
如果我的回答解决了你的疑惑，请采纳，祝学习愉快~
0h019-08-16
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