搭建环境

首先搭建核心环境(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:根节点 -->
<configuration>
<!-- 引入数据库连接
properties:通过resource属性从外部指定properties文件(里面有数据库连接四要素)
-->
<properties resource="database.properties" />
<!--settings:设置MyBatis运行中的一些行为 位置必须在properties下面-->
<settings>
<setting name="logImpl" value="LOG4J"/>
</settings>
<!-- environments:配置MyBatis的多套运行环境 ，
将sql映射到不同的数据库上。改节点下可以配置多个environment,但必须指定一个默认环境
-->
<environments default="development">
<environment id="development">
<transactionManager type="JDBC"></transactionManager>
<dataSource type="POOLED">
<property name="driver" value="${driver}"/>
<property name="url" value="${url}"/>
<property name="username" value="${user}"/>
<property name="password" value="${password}"/>
</dataSource>
</environment>
</environments>
<!-- 引入mappers文件引入配置文件
mappers:告诉MyBatis要去哪里找sql映射文件
-->
<mappers>
<mapper resource="com/lbl/dao/user/UserMapper.xml"/>
</mappers>
</configuration>

配置sql映射文件（UserMapper.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 namespace="com.lbl.dao.user.UserMapper">

<!-- 查询用户表的记录数
id:唯一标识符
resultType:sql语句返回值类型-->

<select id="count" resultType="int">
select count(1) as cuont from smbms_user
</select>
</mapper>