spring註解

下面以註解來替換xml中的
改造前：

  <bean id="userDao" class="com.yihao.dao.impl.UserDaoImpl"/>
  <bean id="userService" class="com.yihao.service.impl.UserSeriveImpl">
          <property name="userDao" ref="userDao"/>
  </bean>

改造後：
UserDaoImpl.java

@Component("userDao")  //<bean id="userDao" class="com.yihao.dao.impl.UserDaoImpl"/>
public class UserDaoImpl implements UserDao {
    public UserDaoImpl(){
        System.out.println("UserDaoImpl saving...");
    }
    public void save() {
        System.out.println("saving...");
    }
}
 

UserSeriveImpl.java

@Component("userService") //<bean id="userService" class="com.yihao.service.impl.UserSeriveImpl">
public class UserSeriveImpl implements UserService {
    @Autowired
    @Qualifier("userDao")    //<property name="userDao" ref="userDao"/>
    private UserDao userDao;
    public void setUserDao(UserDao userDao) {
        this.userDao = userDao;
    }

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

applicationContext.xml

  <!--配置元件掃描-->
  <context:component-scan base-package="com.yihao"></context:component-scan>

小結

<bean id="userDao" class=""/> 相當於 @Component("userDao")
<property name="userDao" ref="userDao"/> 相當於@Autowired @Qualifier("userDao")