mybatis mapper層接口對象的創建

// mybatis配置文件
 String r = "mybatis-config.xml";
 //第一步：獲取輸入流對象
InputStream is = Resources.getResourceAsStream(r);
//第二步：SqlSessionFactoryBuilder 構造器模式構建一個SqlSessionFactory工廠對象
SqlSessionFactory sqlSessionFactory = new  SqlSessionFactoryBuilder().build(is);
//第三步： 創建sqlSession對象
 SqlSession sqlSession = sqlSessionFactory.openSession(true);
 //調用getMapper方法創建mapper接口對象
UserMapper userMapper = sqlSession.getMapper(UserMapper.class); User user = userMapper.myGetUserById(1);
 System.out.println(user);

其中 mybatis-config.xml文件爲：

<?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>
<!-- 引入外部資源文件 -->
<properties resource="jdbc.properties"></properties>
<!-- 設置駝峯匹配 -->
<settings>
  <setting name="mapUnderscoreToCamelCase" value="true"/>
</settings>
<!-- 設置包掃描(別名) -->
<typeAliases>
  <package name="cn.itcast.pojo"/>
</typeAliases>
<!-- 配置環境：可以配置多個環境，default：配置某一個環境的唯一標識，表示默認使用哪個環境 -->
  <environments default="development">
    <environment id="development">
      <transactionManager type="JDBC"/>
      <dataSource type="POOLED">
      	<!-- 配置連接信息 -->
        <property name="driver" value="${jdbc.driverClass}"/>
        <property name="url" value="${jdbc.url}"/>
        <property name="username" value="${jdbc.username}"/>
        <property name="password" value="${jdbc.password}"/>
      </dataSource>
    </environment>
  </environments>
  <!-- 配置映射文件：用來配置sql語句和結果集類型等 -->
  <mappers>
    <mapper resource="UserMapper.xml"/>
  </mappers>
</configuration>

其中 jdbc.properties配置參考爲：

jdbc.driverClass=com.mysql.jdbc.Driver
jdbc.url
=jdbc:mysql://localhost:3306/mybatis?useUnicode=true&characterEncoding=utf-8&serverTimezone=UTC
jdbc.username=root
jdbc.password=123456