NonuniqueBeandDefinitionException-带策略模式的Spring DI

我正在尝试使用Spring实现基于策略模式的通信服务功能。我有以下课程：

接口-MessageService.java

package com.xxx

public Interface MessageService{

    String sendMessage(String idOrNumber);

}

实现类-

package com.xxx

public Interface MessageService{

    String sendMessage(String idOrNumber);

}

1）EmailService.java

package com.xxx

@Component
public class EmailService implements MessageService{

        public String sendMessage(String idOrNumber){

    // Do some operation

    return "success"

    } 

}

package com.xxx

@Component
public class SmsService implements MessageService{

        public String sendMessage(String idOrNumber){

    // Do some operation

    return "success"

    } 

}

2）SmsService.java

package com.xxx

@Component
public class EmailService implements MessageService{

        public String sendMessage(String idOrNumber){

    // Do some operation

    return "success"

    } 

}

package com.xxx

@Component
public class SmsService implements MessageService{

        public String sendMessage(String idOrNumber){

    // Do some operation

    return "success"

    } 

}

通信工厂类

package com.xxx

@Component
public class CommunicationFactory {

    @Resource(name ="smsService")
    private SmsService smsService 


    @Resource(name ="emailService")
    private EmailService emailService;


    public MessageService getCommunicationChannel(String channel){

    MessageService messageService = null;

    if("sms".equals(channel){

    messageService = smsService;    

    }

    if("email".equals(channel){

    messageService = emailService;

    }

   return messageService;

}

我有一个邮件服务实现类

package com.xxx

@Component
@Service
public class CommunicationServiceImpl implements CommunicationService {

      @Autowired
      private MessageService messageService;

      CommunicationFactory communicationFactory;


      @Override
      public String sendCommunication(String idOrNumber){

        //Which implementation be called - SMS or EMAIL
        messageService = communicationFactory.getCommunicationChannel(channel);

        String statusMessage = messageService.sendMessage(idOrNumber);

        }

}

运行服务器时出现以下错误

Caused by: org.springframework.beans.factory.BeanCreationException: Could not autowire field: com.xxx.MessageService com.xxx.CommunicationServiceImpl.messageService; nested exception is 

org.springframework.beans.factory.NoUniqueBeanDefinitionException: No qualifying bean of type [com.xxx.MessageService] is defined: expected single matching bean but found 2: smsService,emailService
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:514) [spring-beans-

3.2.3.RELEASE.jar:3.2.3.RELEASE]
    at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:87) [spring-beans-3.2.3.RELEASE.jar:3.2.3.RELEASE]
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:285) [spring-beans-

3.2.3.RELEASE.jar:3.2.3.RELEASE]
    ... 25 more
Caused by: org.springframework.beans.factory.NoUniqueBeanDefinitionException: No qualifying bean of type [com.xxx.MessageService] is defined: expected single matching bean but found 2: 

smsService,emailService
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:863) [spring-beans-3.2.3.RELEASE.jar:3.2.3.RELEASE]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:768) [spring-beans-3.2.3.RELEASE.jar:3.2.3.RELEASE]
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:486) [spring-beans-

3.2.3.RELEASE.jar:3.2.3.RELEASE]
    ... 27 more 

我错在哪里？任何指针都会有帮助

试试这个

实现类-

1) EmailService.java

package com.xxx

@Component("emailService")
public class EmailService implements MessageService{

        public String sendMessage(String idOrNumber){

    // Do some operation

    return "success"

    } 

}
2) SmsService.java

package com.xxx

@Component("smsService")
public class SmsService implements MessageService{

        public String sendMessage(String idOrNumber){

    // Do some operation

    return "success"

    } 

}

问题在于：

@Autowired
private MessageService messageService;

可能的解决方案是@Autowired这两个服务

@Autowired
private MessageService smsService;
@Autowired
private MessageService emailService;

或者，如果你有同样的问题

@Autowired
@Qualifier("smsService")
private MessageService smsService;
@Autowired
@Qualifier("emailService")
private MessageService emailService;

---

我知道的最简单的实现是依赖注入的服务列表，并使用get方法获取负责的服务：

package com.xxx

@Component
public class CommunicationFactory {

    /**
     * This list would be ordered if the interface is implementing `org.springframework.core.Ordered` or an implementation declares `@org.springframework.core.annotation.Order`(in Spring 4)
     */
    @Autowired
    private List<MessageService> messageServices; 

    /**
     * @return the FIRST communication channel for the given channel
     */
    public MessageService getCommunicationChannel(String channel){
        for (MessageService ms : messageServices) {
            if (ms.supports(channel)) {
                return ms;
            }
        }
        return null; // or a default :)
    }

    /**
     * With this implementation you can even have multiple implementations firing a message if they support the given channel.
     * @return a list of communication channels that support the given channel
     */
    public List<MessageService> getCommunicationChannels(String channel){
        List<MessageService> supporting = new ArrayList<>();
        for (MessageService ms : messageServices) {
            if (ms.supports(channel)) {
                supporting.add(ms);
            }
        }
        return supporting;
    }
}

package com.xxx
@组成部分
公共类通信工厂{
/**
*如果接口正在实现`org.springframework.core.ordered`或实现声明`org.springframework.core.annotation.Order`（在Spring4中），则此列表将被排序
*/
@自动连线
私有列表服务；
/**
*@返回给定通道的第一个通信通道
*/
公共消息服务getCommunicationChannel（字符串通道）{
用于（MessageService ms:messageServices）{
如果（ms支持（通道））{
返回ms；
}
}
返回null；//或默认值：）
}
/**
*使用此实现，如果多个实现支持给定的通道，则您甚至可以让它们触发一条消息。
*@返回支持给定通道的通信通道列表
*/
公共列表getCommunicationChannels（字符串通道）{
列表支持=新建ArrayList（）；
用于（MessageService ms:messageServices）{
如果（ms支持（通道））{
支持。添加（ms）；
}
}
回报支持；
}
}

Dani，我试过你的建议了。它也不起作用。我得到了同样的例外OK，我想你的问题在这里@Autowired private MessageService；，因为当Spring DI尝试注入该引用时，是两个具有相同接口的bean，而Spring无法决定哪一组。定义一个或重新实施这个方法。我喜欢帮助人们获得反对票。。。态度很好。在编辑之前，你的答案是没有解释的代码，这是错误的。默认情况下，bean的名称取自其类型的简单名称。因此，类型为

SmsService

的bean将被称为

SmsService

。在

@Component

注释中显式地给它命名更为清晰，但在这个特定示例中没有任何改变。编辑后，您的答案仍然缺少要点，您已将其作为评论发布。把它编辑进去，也许否决你的人会改变主意。我知道你告诉我的一切，但我是在帮助别人，第一眼我没有看到主要问题，但我不会投反对票给另一个用户，这是在帮助另一个用户，直到放弃这个帖子，当你帮助没有人投赞成票时，但是很快就会得到底片。。。我不理解这种态度，它让我不愿意帮助别人。你在服务课上没有资格。