spring注解

下面以注解来替换xml中的
改造前：

改造后：
UserDaoImpl.java

@Component("userDao")  //
public class UserDaoImpl implements UserDao {
    public UserDaoImpl(){
        System.out.println("UserDaoImpl saving...");
    }
    public void save() {
        System.out.println("saving...");
    }
}

UserSeriveImpl.java

@Component("userService") //
public class UserSeriveImpl implements UserService {
    @Autowired
    @Qualifier("userDao")    //
    private UserDao userDao;
    public void setUserDao(UserDao userDao) {
        this.userDao = userDao;
    }

    @Override
    public void save() {
        this.userDao.save();
    }
}

applicationContext.xml

小结

 相当于 @Component("userDao")
 相当于@Autowired @Qualifier("userDao")