Java类操作

示例

public interface UserService {
}

public class UserServiceImpl implements UserService {
}

@SpringBootTest
class DemoApplicationTests {

    @Test
    void contextLoads() {
        UserServiceImpl userServiceImpl = new UserServiceImpl();

        // 父类 isAssignableFrom 子类
        System.out.println(UserService.class.isAssignableFrom(UserServiceImpl.class)); // true

        // userServiceImpl是否是UserService实例
        System.out.println(userServiceImpl instanceof UserService); // true

        // UserService能否强转为
        System.out.println(UserService.class.isInstance(userServiceImpl)); // true
    }

}