看了别的提问，还是拿不到数据库的值
看了别的提问，能改的都试过了 就是拿不到值。
数据库 密码用户名 都确认了 XML里也是先到home.jsp再跳转
不知道怎么找错了 输出信息里 也没有SQL异常和报错
45
收起
正在回答 回答被采纳积分+1
7回答
我吖吖
2018-05-08 17:43:50
SessionFactoryUtils
package com.wyh.utils;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import java.io.IOException;
import java.io.InputStream;
public class SqlSessionFactoryUtils {
private static String RESOURCE ="mybatis-config.xml";
private static SqlSessionFactory sqlSessionFactory;
private static ThreadLocal<SqlSession> threadLocal = new ThreadLocal<SqlSession>();
// 创建一个初始化SqlSessionFactory的方法
public static void initSqlSessionFactory(){
try {
InputStream is = Resources.getResourceAsStream(RESOURCE);
sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);
} catch (IOException e) {
e.printStackTrace();
}
}
// 获取
public static SqlSessionFactory getSqlSessionFactory(){
return sqlSessionFactory;
}
// 关闭
public static void close(){
SqlSession session = threadLocal.get();
if (session != null){
session.close();
threadLocal.set(null);
}
}
}Mybatis-config-xml
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
<properties resource="db.properties"></properties>
<environments default="development">
<environment id="development">
<transactionManager type="JDBC"/>
<dataSource type="POOLED">
<property name="driver" value="${driver}"/>
<property name="url" value="${url}"/>
<property name="username" value="${username}"/>
<property name="password" value="${password}"/>
</dataSource>
</environment>
</environments>
<mappers>
<mapper resource="mapper/usersMapper.xml"/>
</mappers>
</configuration>db.properties 因为我的mysql 用户名root 密码 111111 所以做了如下更改
driver=com.mysql.jdbc.Driver url=jdbc:mysql://localhost:3306/mydb username=root password=111111
index.jsp
<%--
Created by IntelliJ IDEA.
User: Administrator
Date: 2018/5/7/007
Time: 17:59
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<html>
<head>
<title>用户管理中心</title>
<link rel="stylesheet" href="lib/bootstrap-3.3.7-dist/css/bootstrap.min.css">
<script src="lib/2.2.4/jquery-1.12.4.min.js"></script>
<script src="lib/bootstrap-3.3.7-dist/js/bootstrap.min.js"></script>
</head>
<body>
<div class="container">
<div class="row">
<div class="page-header">
<h1>后台管理系统<small>用户数据管理中心</small></h1>
</div>
</div>
<div class="row">
<div class="jumbotron">
<h1>MyBatis基础 ！</h1>
<p>通过一个项目完成基础部分的学习</p>
<p><a class="btn btn-primary btn-lg" href="#" role="button">查看更多</a></p>
</div>
</div>
<div class="row">
<table class="table table-hover table-striped">
<tr>
<th>用户编号</th>
<th>登陆账号</th>
<th>用户昵称</th>
<th>邮箱</th>
<th>联系方式</th>
<th>账号创建时间</th>
<th>用户状态</th>
<th>操作</th>
</tr>
<c:forEach var="user" items="${userList}">
<tr>
<td>123</td>
<td>213</td>
<td>1</td>
<td>1</td>
<td>4</td>
<td>4</td>
<td>314</td>
<td>5r23</td>
<td>213</td>
<td>132</td>
</tr>
</c:forEach>
</table>
</div>
</div>
</body>
</html>只要加了 <c:forEach var="user" items="${userList}"> 我的底下的 <td>标签里的测试数据就会消失 所以我感觉这是没有从数据库取到数据的缘故
我吖吖
2018-05-08 13:56:55
usersMapper.xml
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<!--
mapper用于定义一个映射配置的根节点
namespace属性用来配置命名空间，主要进行session级别的缓存管理
命名空间默认情况下，使用我们当前操作的实体类的全路径
-->
<mapper namespace="com.wyh.entity.Users">
<select id="findAll" resultType="com.wyh.entity.Users">
select * FROM USERS;
</select>
</mapper>
UsersFindServlet.java
package com.wyh.utils;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import java.io.IOException;
import java.io.InputStream;
public class SqlSessionFactoryUtils {
private static String RESOURCE ="mybatis-config.xml";
private static SqlSessionFactory sqlSessionFactory;
private static ThreadLocal<SqlSession> threadLocal = new ThreadLocal<SqlSession>();
// 创建一个初始化SqlSessionFactory的方法
public static void initSqlSessionFactory(){
try {
InputStream is = Resources.getResourceAsStream(RESOURCE);
sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);
} catch (IOException e) {
e.printStackTrace();
}
}
// 获取
public static SqlSessionFactory getSqlSessionFactory(){
return sqlSessionFactory;
}
// 关闭
public static void close(){
SqlSession session = threadLocal.get();
if (session != null){
session.close();
threadLocal.set(null);
}
}
}
我吖吖
2018-05-08 13:55:00
UsersDao.java
package com.wyh.dao;
import com.wyh.entity.Users;
import com.wyh.utils.SqlSessionFactoryUtils;
import org.apache.ibatis.session.SqlSession;
import java.util.List;
public class UsersDao {
private SqlSession sqlSession=SqlSessionFactoryUtils.getSqlSessionFactory().openSession();
private List<Users> list;
public List<Users> findAll(){
try {
list =sqlSession.selectList("findAll");
} catch (Exception e) {
e.printStackTrace();
}finally {
sqlSession.close();
}
return list;
}
}
Java数据库开发与实战应用2018版
- 参与学习 人
- 提交作业 277 份
- 解答问题 4297 个
Java数据库开发的必备技能，从流行的MySQL数据库开始，到Java原生的数据库管理接口JDBC的使用，再到常用的数据持久化框架MyBatis，让你向Java工程师的目标又迈进了一步！
了解课程
恭喜解决一个难题，获得1积分~
来为老师/同学的回答评分吧
0 星