@Resource注入

1、根据名称注入

    @Resource(name = "userService")
    private UserService userService;

@Service("userService")
public class UserServiceImpl implements UserService

2、不指定名称，根据属性名进行注入

    @Resource
    private UserService userService;

@Service("userService")
public class UserServiceImpl implements UserService

 3、根据类型进行注入

    @Resource
    private UserService userService;

@Service
public class UserServiceImpl implements UserService