Question

好的，所以，我有一个创建两个bean的配置类。它们定义如下：

public class FileUploadConfiguration {

    public static final String UPLOAD_PREFIX = "file.upload";

    @Bean(name = "fileService", autowire = Autowire.BY_TYPE)
    @DependsOn("fileUploadPaths")
    @Autowired
    public CRUDFileService fileService(@Qualifier("fileUploadPaths") PrefixedPropertyFactoryBean fileUploadPaths) throws Exception {
        Map<String, String> paths = Maps.fromProperties(fileUploadPaths.getObject());
        return new CRUDFileService(File.class.getName(), paths);
    }

    @Bean(name = "fileUploadPaths")
    public PrefixedPropertyFactoryBean fileUploadPaths(Environment environment) {
        PrefixedPropertyFactoryBean fileUploadPaths = new PrefixedPropertyFactoryBean();
        fileUploadPaths.setPrefix(UPLOAD_PREFIX);
        fileUploadPaths.setLocations(ResourceUtils.getActiveResources(environment));
        return fileUploadPaths;
    }
}

如果我在两个实例中都放置断点，则流程如下：

1） fileUploadPaths 被实例化，看起来对我来说是正确的。

2） fileService 获得实例化，但通过 FileUploadConfiguration bean创建的 postProcessPropertyValues ...这对我来说似乎很奇怪。 enter image description here

3）之后，我得到一个例外，因为看起来Spring似乎再次尝试创建 fileService ，但现在通过 createBean ，并且由于某种原因，@ Qualifier关于参数定义似乎被忽略了。

线程中的异常＆＃34; main＆＃34; org.springframework.beans.factory.UnsatisfiedDependencyException：创建名称为＆＃39; fileService＆＃39;的bean时出错在课堂上定义 x.y.z.FileUploadConfiguration：表达不满意的依赖关系通过索引为0的构造函数参数 [a.b.c.PrefixedPropertyFactoryBean]：不明确的工厂方法参数 types - 您是否将正确的bean引用指定为工厂方法参数呢？在 org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray（ConstructorResolver.java:735）在 org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod（ConstructorResolver.java:464）在 org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod（AbstractAutowireCapableBeanFactory.java:1119）在 org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance（AbstractAutowireCapableBeanFactory.java:1014）在 org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean（AbstractAutowireCapableBeanFactory.java:504）在 org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean（AbstractAutowireCapableBeanFactory.java:476）在 org.springframework.beans.factory.support.AbstractBeanFactory $ 1.getObject（AbstractBeanFactory.java:303）在 org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton（DefaultSingletonBeanRegistry.java:230）在 org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean（AbstractBeanFactory.java:299）在 org.springframework.beans.factory.support.AbstractBeanFactory.getBean（AbstractBeanFactory.java:194）在 org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons（DefaultListableBeanFactory.java:755）在 org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization（AbstractApplicationContext.java:757）在 org.springframework.context.support.AbstractApplicationContext.refresh（AbstractApplicationContext.java:480）在 org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh（EmbeddedWebApplicationContext.java:118）

注意：如果我将 fileService 定义更改为以下内容，则会修复此问题：

@Bean(name = "fileService")
@DependsOn("fileUploadPaths")
@Autowired
public CRUDFileService fileService(@Qualifier("fileUploadPaths") PrefixedPropertyFactoryBean fileUploadPaths, AutowireCapableBeanFactory factory) throws Exception {
    Map<String, String> paths = Maps.fromProperties(fileUploadPaths.getObject());
    CRUDFileService crudFileService = new CRUDFileService(File.class.getName(), paths);
    factory.autowireBean(crudFileService);
    return crudFileService;
}

因此，我不是让Spring通过 @Bean（autowire = Autowire.BY_TYPE）自动装配我的bean，而只是自动装配 AutowireCapableBeanFactory 并自动装配 CRUDFileService < / strong> bean我自己。

我的问题是：为什么会发生这种行为？我正确使用 @Bean（autowire = Autowire.BY_TYPE）吗？我之前使用它并且它像魅力一样工作，除了我没有像我用这个那样自动调整bean方法参数。

Answer 1

我看到的问题是你试图将Spring FactoryBean作为依赖注入另一个bean。 FactoryBean是特殊的，它是一个bean的工厂，结果bean是你应该注入其他对象的。

因此，假设您在CRUDFileService中的依赖项是Properties类而不是FactoryBean，如果您要尝试这样做，它应该干净利落：

public class FileUploadConfiguration {

    public static final String UPLOAD_PREFIX = "file.upload";

    @Bean(name = "fileService", autowire = Autowire.BY_TYPE)
    @Autowired
    public CRUDFileService fileService(@Qualifier("fileUploadPaths") Properties fileUploadPaths) throws Exception {
        Map<String, String> paths = Maps.fromProperties(fileUploadPaths);
        return new CRUDFileService(File.class.getName(), paths);
    }

    @Bean(name = "fileUploadPaths")
    public PrefixedPropertyFactoryBean fileUploadPaths(Environment environment) {
        PrefixedPropertyFactoryBean fileUploadPaths = new PrefixedPropertyFactoryBean();
        fileUploadPaths.setPrefix(UPLOAD_PREFIX);
        fileUploadPaths.setLocations(ResourceUtils.getActiveResources(environment));
        return fileUploadPaths;
    }
}

Spring @Bean autowire（） - 第二次（？）时间失败

1 个答案: