MyBatis Mapper代理实现DAO

 

mapper接口遵循的开发约定

1、mapper.xml中namespace属性等于mapper接口的地址

2、mapper接口中的方法名和mapper.xml中statement的id一致

3、mapper接口中的方法参数类型和mapper.xml中的statement的parameterType类型一致

4、mapper接口中的方法返回类型和mapper.xml中的statement的resultType类型一致

 

 

sqlMapConfig.xml中加载配置采用包扫描的方式，定义别名也采用包扫描的方式

<typeAliases>
	<package name="entity" />
</typeAliases>	
<mappers>
	<package name="mapper"/>
</mappers>

 

定义mapper接口，接口的参数和返回值需要和mapper.xml文件中的parameterType、resutlType一致

public interface IUserMapper {
	public User findUserById(User entity);
	public List<User> findAll();
}

创建配置文件，namespace的名称和IUserMapper接口的全路径名一致

<mapper namespace="mapper.IUserMapper">
	<select id="findAll" resultType="entity.User">
		select * from user
	</select>

	<select id="findUserById" parameterType="entity.User" resultType="entity.User">
		select * from user where id=#{id}
	</select>
</mapper>

 测试类

public class TestMapperDAO {
	public static final String RESOURCE = "sqlMapConfig.xml"; // 配置文件
	SqlSessionFactory sqlSessionFactory;// Session工厂

	@Before
	public void initFactory() throws IOException {
		InputStream in = Resources.getResourceAsStream(RESOURCE);// 配置文件的输入流
		sqlSessionFactory = new SqlSessionFactoryBuilder().build(in); // 获得sqlSessionFactory
	}

	@Test
	public void testFindAll() {
		SqlSession session = sqlSessionFactory.openSession();
		IUserMapper mapper = session.getMapper(IUserMapper.class);
		User u = new User();
		u.setId("1");
		User user = mapper.findUserById(u);
		System.out.println(user);
		
		List<User> users = mapper.findAll();
		System.out.println(users);
	}
}