Mybatis 第一个例子优化，优化配置文件

config.properties

driver=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/test
username=root
password=123456

configuration.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>
  <!-- 导入配置文件 -->
  <properties resource="config.properties"></properties>
  
  <!-- 配置别名 -->
  <typeAliases>
    <typeAlias type="com.test.bean.User" alias="User"/>
  </typeAliases>
  
  <!-- 配置环境 -->
  <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>
  
  <!-- 配置映射 -->
  <mappers>
    <mapper resource="userMapper.xml"/>
  </mappers>
</configuration>