Spring注释，散集积累（三）

@Configuration

传统方式：

 

<beans>  
	<bean id="orderService" class="com.acme.OrderService"/>  
		<constructor-arg ref="orderRepository"/>  
	</bean>  
	<bean id="orderRepository" class="com.acme.OrderRepository"/>  
		<constructor-arg ref="dataSource"/>  
	</bean>  
</beans>  

 

 

ApplicationContext ctx = new ClassPathXmlApplicationContext("application-config.xml");  
OrderService orderService = (OrderService) ctx.getBean("orderService");  

 注解方式：

 

@Configuration  
public class ApplicationConfig {  
  
		public @Bean OrderService orderService() {  
				return new OrderService(orderRepository());  
		}  
  
		public @Bean OrderRepository orderRepository() {  
				return new OrderRepository(dataSource());  
		}  
  
		public @Bean DataSource dataSource() {  
				// instantiate and return an new DataSource …  
		}  
}  

 

JavaConfigApplicationContext ctx = new JavaConfigApplicationContext(ApplicationConfig.class);  
OrderService orderService = ctx.getBean(OrderService.class);  

 

 

@Scope("prototype")

 

@Scope("prototype")  
public class PrintTask2 implements Runnable {  
        String name;  
  
        public void setName(String name) {  
                this.name = name;  
        }  
          
        @Override  
        public void run(){  
                System.out.println(name + " is running.");  
                try{  
                        Thread.sleep(5000);  
                }catch(InterruptedException e){  
                        e.printStackTrace();  
                }  
                System.out.println(name + " is running again.");  
        }  
} 

 

 

如果action或Service中不@Scope("prototype")，有可能报找不到xxxaction或Service的错误！写上这个就表示每次请求都重新创建一个action或Service，与SINGALON对应，俗称“多例”。

@Component

 

@Component  
@Scope("prototype")  
public class PrintTask2 implements Runnable {  
        String name;  
  
        public void setName(String name) {  
                this.name = name;  
        }  
          
        @Override  
        public void run(){  
                System.out.println(name + " is running.");  
                try{  
                        Thread.sleep(5000);  
                }catch(InterruptedException e){  
                        e.printStackTrace();  
                }  
                System.out.println(name + " is running again.");  
        }  
}

把普通pojo实例化到spring容器中，相当于配置文件中的<bean id="" class=""/>

 

@Repository

 

@Repository
public class DaoImpl implements IDao{
｝

 应用于Dao层，把该类注册到Spring容器中

 

 

@Service

 

@Service
public class ServiceImpl implements IService {
	@Autowired
	private IDao iDao;  
}

 应用于Service层，把该类注册到Spring容器中

 

 

@Controller

 

@Controller
public class TestController {
    @Autowired
    private IService iService;
}

  应用于Action层，把该类注册到Spring容器中

 

@Autowired , @Qualifier("XXX")

 

@Service  
public class TestServiceImpl {  
    @Autowired  
    @Qualifier("iTestDao2")  
    private ITestDao iTestDao;  
}  

在ITestDao接口标上@Autowired和@Qualifier注释使得ITestDao接口存在两个实现类的时候必须指定其中一个来注入，使用实现类首字母小写的字符串("iTestDao2")来注入。否则可以省略，只写@Autowired