MyBatis workflow

MyBatis workflow

MyBatis Core Objects

• SqlSessionFactoryBuilder

The SqlSession factory builder object uses the constructor pattern to create the SqlSession factory object.

• SqlSessionFactory

SqlSession factory, use factory pattern to create SqlSession object.

• SqlSession

This object can operate the database, and can also use the dynamic proxy mode to create a proxy object of the persistence layer interface to operate the database.

• Mapper

The proxy object of the persistence layer interface, which implements the persistence layer interface and is used to operate the database.

MyBatis workflow

1. Create a SqlSessionFactoryBuilder object
2. The SqlSessionFactoryBuilder object builds the SqlSessionFactory object: Constructor mode
3. The SqlSessionFactory object produces the SqlSession object: factory mode
4. The SqlSession object creates a proxy object for the persistence layer interface: dynamic proxy mode
5. The proxy object operates the database

The StudentDao.xml file is as follows:

<?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="com.mapper.StudentMapper">
    <select id="selectStudentList" resultType="com.entity.Student">
       select * from student;
    </select>
</mapper>

The Dao layer code is as follows:

public interface StudentMapper {
    
    
    List<Student> selectStudentList();
}

The test code is as follows:

@Test
public void testSelectStudentList() throws Exception {
    
    
    // （1）读取核心配置文件
    InputStream is = Resources.getResourceAsStream("mybatis-config.xml");
    // （2）创建SqlSessionFactoryBuilder对象
    SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
    // （3）SqlSessionFactoryBuilder对象获取SqlSessionFactory对象
    SqlSessionFactory factory = builder.build(is);
    // （4）SqlSessionFactory对象获取SqlSession对象
    SqlSession session = factory.openSession();
    // （5）SqlSession对象获取代理对象
    UserMapper studentMapper = session.getMapper(StudentMapper.class);
    // （6）代理对象执行方法
    List<Student> list = studentMapper.selectStudentList();
    list.forEach(System.out::println);
    // （7）释放资源
    session.close();
    is.close();
}