mybatis mapper接口 Mybatis mapper接口动态代理开发步骤解析

时间:2021-01-29 jock_javaEE 人气:0

一、必须遵守的四项原则

1：接口方法名==xx.xml中的id名

2：方法返回值类型与Mapper.xml文件中返回值类型一致

3：方法的入参类型与Mapper.xml文件中入参值类型一致

4：命名空间绑定接口

二、代码

public class UserMapperTest {

private SqlSession sqlSession;

private InputStream in;

@Before
public void before() throws IOException {
  //1.读取配置文件
  in = Resources.getResourceAsStream("SqlMapConfig.xml");
  //2.创建 SqlSessionFactory 的构建者对象
  SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
  //3.使用构建者创建工厂对象 SqlSessionFactory
  SqlSessionFactory sqlSessionFactory = builder.build(in);
   sqlSession = sqlSessionFactory.openSession();

}

@After
public void after() throws IOException {
  //7.释放资源
  sqlSession.close();
  in.close();
}

@Test
public void findUserById() {
  UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
  List<User> users = userMapper.findAll();
  for (User user : users) {
    System.out.println(user);
  }
}
}

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