spring boot注入jar包中的接口总是提示that could not be found

Question

首先是在spring boot项目中注入的jar包中的接口

 @Controller
public class MessageTransferStationController {

    @Autowired
    private MessageClient messageClient;
}

其次，jar包中的MessageClient的源码

public interface MessageClient {
}

MessageClient分别有三个实现类

public class CoreMessageClient implements MessageClient {}


@Component
public class SpringMessageClientImpl extends CoreMessageClient implements MessageClient {}


public class Spring2MessageClientImpl extends CoreMessageClient implements MessageClient {}

当我在spring boot项目中注入MessageClient接口的时候，启动报错：

017-06-12 15:06:53.281 WARN 9780 --- [ main] ationConfigEmbeddedWebApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'messageTransferStationController': Unsatisfied dependency expressed through field 'messageClient'; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'com.sinosoft.messageclient.MessageClient' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
2017-06-12 15:06:53.283 INFO 9780 --- [ main] o.apache.catalina.core.StandardService : Stopping service Tomcat
2017-06-12 15:06:53.316 INFO 9780 --- [ main] utoConfigurationReportLoggingInitializer :

Error starting ApplicationContext. To display the auto-configuration report re-run your application with 'debug' enabled.
2017-06-12 15:06:53.431 ERROR 9780 --- [ main] o.s.b.d.LoggingFailureAnalysisReporter :

---

APPLICATION FAILED TO START

---

Description:

Field messageClient in com.sinosoft.oa.message_transfer_station.web.MessageTransferStationController required a bean of type 'com.sinosoft.messageclient.MessageClient' that could not be found.

Action:

Consider defining a bean of type 'com.sinosoft.messageclient.MessageClient' in your configuration.

Process finished with exit code 1

---

请问各位大佬，为什么MessageClient为什么不能注入，我猜想过MessageClient的实现类没有被Spring管理，我看了jar包中源码有一个实现类加上了@Component注解

求教各位大佬，这是什么原因引起的？

注：引用jar包中的其它接口也测试过了，同样的错误，也就是说引用的这个jar包中的所有接口都没有被spring管理，或者没有扫描。

Answer 1

多次实验后，发现引进来的jar包没有被spring管理，即时jar包中有spring注解。
在主启动类上加入@ComponentScan("/")，问题得到了解决