properties屬性不常用

例項：

1.專案完整結構目錄

properties-config.properties

jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/mybatis
jdbc.username=root
jdbc.password=shapolang

<?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>
  
  <!-- 
  	mybatis可以使用properties來引入外部properties配置檔案的內容
	resource：引入類路徑下的資源
	url:映入網路路徑或者磁碟路徑下的資源
   -->
  <properties resource="properties-config.properties"></properties>
  
	<!-- 在控制檯列印sql語句 -->
	<settings>  
        <setting name="logImpl" value="STDOUT_LOGGING"/>  
    </settings> 
 
  <environments default="development">
    <environment id="development">
      <transactionManager type="JDBC"/>
      <dataSource type="POOLED">
        <property name="driver" value="${jdbc.driver}"/>
        <property name="url" value="${jdbc.url}"/>
        <property name="username" value="${jdbc.username}"/>
        <property name="password" value="${jdbc.password}"/>
      </dataSource>
    </environment>
  </environments>
  
  <!-- 寫好的sql對映檔案一定要註冊到全域性配置檔案中 -->
  <mappers>
    <mapper resource="com/mybatis/bean/EmployeeMapper.xml"/>
  </mappers>
</configuration>