MyBatis入门配置及操作

需要准备的jar包：mybatis.x.x.x.jar、mysql包。

编写mybatis的配置文件SqlMapConfig.xml，这里以mysql的连接为例：

<?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="com.mysql.jdbc.Driver"/>
        <property name="url" value="jdbc:mysql://localhost:3306/mybatis"/>
        <property name="username" value="root"/>
        <property name="password" value="123456"/>
      </dataSource>
    </environment>
  </environments>
  <mappers>
    <mapper resource="config/UserMapper.xml"/>
  </mappers>
</configuration>

编写与数据库表对应的实体类以及实体类映射文件（实体类略）：

<?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="test">
<!-- 参数类型为占位符所代表的常量类型，结果类型为查询返回的实体类型 -->
<select id="findUserById" parameterType="int" resultType="entity.User">
select * from user where id=#{id}
</select>
</mapper>  

编写主函数：

public static void main(String[] args) throws IOException {
String resource="config/SqlMapConfig.xml";
//加载配置文件
InputStream inputStream=Resources.getResourceAsStream(resource);
//获取session工厂
SqlSessionFactory sqlSessionFactory=new SqlSessionFactoryBuilder().build(inputStream);
//获取session
SqlSession sqlSession=sqlSessionFactory.openSession();
User user=sqlSession.selectOne("test.findUserById", 1);
System.out.print(user.toString());
}