如何注释自定义 Spring Boot 自定义存储库？

Question

我有一个名为 Screenshot 的实体类和一个声明如下的存储库：

public interface ScreenshotRepository extends JpaRepository<Screenshot, UUID>, ScreenshotRepositoryCustom

自定义存储库的定义如下：

interface ScreenshotRepositoryCustom

和

class ScreenshotRepositoryImpl implements ScreenshotRepositoryCustom {
    private final ScreenshotRepository screenshotRepo;

    @Autowired
    public ScreenshotRepositoryImpl(ScreenshotRepository screenshotRepo) {
        this.screenshotRepo = screenshotRepo;
    }

这是在另一个 Stack Overflow 问题中描述的：How to add custom method to Spring Data JPA

现在，IntelliJ 给我一个警告：

Autowired members must be defined in a valid Spring bean

我尝试将这些注释添加到ScreenshotRepositoryImpl，但没有一个起作用：

• @Repository
• @Component
• @Service

但没有任何工作。显然有些是错误的，但我正在尝试。什么是正确的注释。

使用@Repository，我收到此错误：

2017-11-23 12:30:04.064  WARN 20576 --- [  restartedMain] ationConfigEmbeddedWebApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'screenshotsController' defined in file [C:\Users\pupeno\Documents\Dashman\java\dashmanserver\out\production\classes\tech\dashman\server\controllers\ScreenshotsController.class]: Unsatisfied dependency expressed through constructor parameter 0; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'screenshotRepositoryImpl' defined in file [C:\Users\pupeno\Documents\Dashman\java\dashmanserver\out\production\classes\tech\dashman\server\models\ScreenshotRepositoryImpl.class]: Unsatisfied dependency expressed through constructor parameter 0; nested exception is org.springframework.beans.factory.BeanCurrentlyInCreationException: Error creating bean with name 'screenshotRepositoryImpl': Requested bean is currently in creation: Is there an unresolvable circular reference?
2017-11-23 12:30:04.064  INFO 20576 --- [  restartedMain] j.LocalContainerEntityManagerFactoryBean : Closing JPA EntityManagerFactory for persistence unit 'default'
2017-11-23 12:30:04.064  INFO 20576 --- [  restartedMain] o.apache.catalina.core.StandardService   : Stopping service [Tomcat]
2017-11-23 12:30:04.080  INFO 20576 --- [  restartedMain] utoConfigurationReportLoggingInitializer : 

Error starting ApplicationContext. To display the auto-configuration report re-run your application with 'debug' enabled.
2017-11-23 12:30:04.080 ERROR 20576 --- [  restartedMain] o.s.b.d.LoggingFailureAnalysisReporter   : 

***************************
APPLICATION FAILED TO START
***************************

Description:

The dependencies of some of the beans in the application context form a cycle:

   screenshotsController defined in file [C:\Users\pupeno\Documents\Dashman\java\dashmanserver\out\production\classes\tech\dashman\server\controllers\ScreenshotsController.class]
┌─────┐
|  screenshotRepositoryImpl defined in file [C:\Users\pupeno\Documents\Dashman\java\dashmanserver\out\production\classes\tech\dashman\server\models\ScreenshotRepositoryImpl.class]
└─────┘

Answer 1

发生了什么？

你的依赖形成了一个循环：ScreenshotRepository 扩展了ScreenshotRepositoryCustom，但ScreenshotRepositoryCustom 的实现依赖于ScreenshotRepository。由于这个循环，没有一个 bean 可以完成它们的实例化。

建议的解决方案

Spring Data 在这些场景中不支持通过构造函数进行注入。尝试这样做会导致依赖循环错误。为了能够将ScreenshotRepository 注入ScreenShotRepositoryImpl，您需要通过字段进行注入：

@Repository
public class ScreenshotRepositoryImpl implements ScreenshotRepositoryCustom {

    @Autowired
    ScreenshotRepository screenshotRepository ;

    ...

}