Autowire的Spring护套不工作。创建bean时出错

Question

嗨，我有一个spring boot项目。主类包如下所示：

com.som.demo

我在项目中使用了一个外部jar作为maven依赖项。在该jar中，有一个用@service注释的服务类，如下所示：

@Service
public class SomeServiceImpl implements SomeService {
      @Autowired
      private TreeCacheWrapper ffCoreCache;

      @Autowired(required = false)
      private ZookeeperProperties zookeeperProperties;

      public SomeServiceImpl(TreeCacheWrapper ffCoreCache, ZookeeperProperties zookeeperProperties) {
         this.ffCoreCache = ffCoreCache;
         this.zookeeperProperties = zookeeperProperties;
      }
}

其中SomeServiceImpl类的主包如下所示：

com.som.test

现在，在我的项目中，当我自动连接类时，我在运行spring boot应用程序时遇到了bean创建错误。我就是这样做的：

@Autowired
private SomeService someService;

错误：

 org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'someServiceImpl'
Unsatisfied dependency expressed through field 'ffCoreCache'; 
nested exception is org.springframework.beans.factory.BeanCreationException: 
Error creating bean with name 'ffCoreCache' defined in class path resource [com/som/test/config/ZooKeeperConfig.class]: 
Bean instantiation via factory method failed; 
nested exception is org.springframework.beans.BeanInstantiationException: 
Failed to instantiate [com.som.test.cache.TreeCacheWrapper]: 
Factory method 'ffCoreCache' threw exception; 
nested exception is java.lang.NoClassDefFoundError: org/apache/curator/retry/ExponentialBackoffRetry


Caused by: org.springframework.beans.factory.BeanCreationException: 
Error creating bean with name 'ffCoreCache' defined in class path resource [com/som/test/config/ZooKeeperConfig.class]: 
Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: 
Failed to instantiate [com.som.test.cache.TreeCacheWrapper]: 
Factory method 'ffCoreCache' threw exception; nested exception is java.lang.NoClassDefFoundError: org/apache/curator/retry/ExponentialBackoffRetry



Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.som.test.cache.TreeCacheWrapper]: 
Factory method 'ffCoreCache' threw exception; nested exception is java.lang.NoClassDefFoundError: org/apache/curator/retry/ExponentialBackoffRetry

Caused by: java.lang.NoClassDefFoundError: org/apache/curator/retry/ExponentialBackoffRetry

Caused by: java.lang.ClassNotFoundException: org.apache.curator.retry.ExponentialBackoffRetry

Answer 1

Spring Boot默认扫描到主包中的bean。您可以使用

@SpringBootApplication(scanBasePackages={"com.som.demo" , "com.som.test"})

Answer 2

用@服务而不是实现类注释服务接口，并尝试用@组件注释ServiceImplementation类。

Answer 3

当Spring Boot应用程序启动时，它会扫描与您的主类相同的包中的bean，以及它下面的所有包。

因为您的主类驻留在包com中。som。演示spring boot将在此包中或类似com的包中找到任何bean。som。演示。示例1，com。som。演示。a、 b.c等，但不会扫描com。som。测试包，因为它是主包的“对等”包。

通常，您可以在接受要扫描的基本包列表的ComponentScan注释的帮助下，配置spring boot来扫描您选择的包。您可以将此注释放在主类上（位于SpringBootApplication旁边）。

然而，这有点违背了Spring靴的惯例。

有关更多技术细节和示例，请阅读本教程。