mybatis学习之路

1：mybatis是一个持久化框架（框架：整体解决方案）

之前：JDBC->jdbcTemplate；工具

功能简单：sql语句编写在java代码里面，硬编码高耦合的方式

Hibernate:全自动ORM（Object Relation Mapping）框架，旨在消除sql，中间过程都是黑箱操作。HQL支持定制sql。

Mybatis：半自动，轻量级的框架

　　　　编写sql从黑相中提取出来，可以有开发人员编写。

 mybatis的配置文件

<?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>
  <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="org/mybatis/example/BlogMapper.xml"/>
  </mappers>
</configuration>

加载mybatis的配置文件，创建sqlSessionFactory

String resource = "org/mybatis/example/mybatis-config.xml";
InputStream inputStream = Resources.getResourceAsStream(resource);
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

从sqlSessionFactory中获取sqlSession

SqlSession session = sqlSessionFactory.openSession();
try {
  Blog blog = (Blog) session.selectOne("org.mybatis.example.BlogMapper.selectBlog", 101);
} finally {
  session.close();
}

映射的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="org.mybatis.example.BlogMapper">
  <select id="selectBlog" resultType="Blog">
    select * from Blog where id = #{id}
  </select>
</mapper>