mybatis源码阅读之2：mybatis执行流程

1.获取sqlSessionFactory对象

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

 配置文件mybatis-config.xml的各项配置，后续章节会单独讲解。

2.获取SqlSession对象

SqlSession session = sqlSessionFactory().openSession(true);

SqlSession openSession(boolean autoCommit):true表示自动提交 

SqlSession代表和数据库的一次会话，用完必须关闭。

同样，sqlsession和connecttion一样，都是线程不安全的，每次使用，都要去获取。

3.获取接口的代理对象MapperProxy

1.首先自定义个Mapper接口

public interface StudentMapper {

	public int addStudent(Student s);

	public int updateStudent(Student s);

	public int deleteById(Long id);

	public Student findOneById(Long id);

	public Student findAll();

}

2.定义mapper接口对用的sql.xml文件

<?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.licw.lean.mybatis_anayl.StudentMapper">

	<insert id="addStudent" parameterType="com.licw.lean.mybatis_anayl.Student">
		INSERT INTO studentTab
		(name,age) VALUES (#{name},#{age})
	</insert>

	<update id="updateStudent" parameterType="com.licw.lean.mybatis_anayl.Student">
		UPDATE studentTab SET
		name =#{name},age=#{age} WHERE id=#{id}
	</update>

	<delete id="deleteById" parameterType="java.lang.Long">
		DELETE FROM studentTab
		WHERE id =#{id}
	</delete>

	<select id="findOneById" parameterType="java.lang.Long">
		SELECT * FROM studentTab
		WHERE id=#{id}
	</select>

	<select id="findAll" resultType="com.licw.lean.mybatis_anayl.Student">
		SELECT * FROM studentTab
	</select>

</mapper>

3.通过SqlSeesion获取Mapper的代理

StudentMapper mapper = session.getMapper(StudentMapper.class);

4.执行增删改查方法

Student s = new Student("12344", 32);
int nums = mapper.addStudent(s);

5.关闭session

session.close();

以上5个步骤中，抛出异常部分没有写出来，实际写代码过程中，要注意异常的捕获，因为这个不是本系列的重点，就不罗列了