java - 在运行时创建 Spring Bean

Question

我尝试使用@Configuration 和@Bean 注释在运行时创建bean。这样做的原因是我试图让 Spring 了解创建的 bean，以便它可以处理我正在创建的应用程序的调度。我已经像这样定义了带注释的类:

@Configuration  
public class GathererConfigBean {
    @Bean(name = "FactoryBean")
    public MethodInvokingJobDetailFactoryBean createMethodInvokingJobDetail(String service, Object obj, String method) throws ClassNotFoundException, NoSuchMethodException{
        MethodInvokingJobDetailFactoryBean jobDetailFactory = new MethodInvokingJobDetailFactoryBean();
        jobDetailFactory.setBeanName(service + "FactoryBean");
        jobDetailFactory.setTargetObject(obj);
        jobDetailFactory.setTargetMethod(method);
        jobDetailFactory.setConcurrent(false);
        jobDetailFactory.afterPropertiesSet();
        return jobDetailFactory;
    }

    @Bean(name = "TriggerBean")
    public CronTriggerBean createTriggerBean(String service, JobDetail job, String schedule) throws ParseException{
        CronTriggerBean trigger = new CronTriggerBean();
        trigger.setBeanName(service + "TriggerBean");
        trigger.setJobDetail(job);
        trigger.setCronExpression(schedule);
        return trigger;
    }

    public CronTrigger createTrigger(String service, JobDetail job, String schedule) throws ParseException{
        return createTriggerBean(service, job, schedule);
    }

    public JobDetail createJobDetail(String service, AbstractGatherer obj, String method) throws ClassNotFoundException, NoSuchMethodException{
        return (JobDetail) createMethodInvokingJobDetail(service, obj, method).getObject();
    }
}

问题是，当我运行这个程序时，我总是遇到以下异常，并且我无法找到我在网上所做的类似示例。最初，我以为这是因为它们具有相同的名称，但事实似乎并非如此，因为当我运行一个时，我得到了相同的错误。

    Exception in thread "main" org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'FactoryBean' defined in class path resource [com/linuxbox/enkive/statistics/gathering/GathererConfigBean.class]: Unsatisfied dependency expressed through constructor argument with index 0 of type [java.lang.String]: : No matching bean of type [java.lang.String] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {}; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No matching bean of type [java.lang.String] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {}
Related cause: org.springframework.beans.factory.BeanCurrentlyInCreationException: Error creating bean with name 'FactoryBean': Requested bean is currently in creation: Is there an unresolvable circular reference?
    at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:730)
    at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:461)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:983)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:879)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:485)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:456)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:291)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:288)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:190)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:563)
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:895)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:425)
    at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:139)
    at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:93)
    at com.linuxbox.enkive.Main.run(Main.java:54)
    at com.linuxbox.enkive.MainJettyWebApps.main(MainJettyWebApps.java:53)
Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No matching bean of type [java.lang.String] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {}
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.raiseNoSuchBeanDefinitionException(DefaultListableBeanFactory.java:920)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:789)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:703)
    at org.springframework.beans.factory.support.ConstructorResolver.resolveAutowiredArgument(ConstructorResolver.java:795)
    at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:723)
    ... 16 more
Related cause:
org.springframework.beans.factory.BeanCurrentlyInCreationException: Error creating bean with name 'FactoryBean': Requested bean is currently in creation: Is there an unresolvable circular reference?
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.beforeSingletonCreation(DefaultSingletonBeanRegistry.java:297)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:216)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:288)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getTypeForFactoryBean(AbstractBeanFactory.java:1343)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.getTypeForFactoryBean(AbstractAutowireCapableBeanFactory.java:678)
    at org.springframework.beans.factory.support.AbstractBeanFactory.isTypeMatch(AbstractBeanFactory.java:507)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBeanNamesForType(DefaultListableBeanFactory.java:317)
    at org.springframework.beans.factory.BeanFactoryUtils.beanNamesForTypeIncludingAncestors(BeanFactoryUtils.java:185)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.findAutowireCandidates(DefaultListableBeanFactory.java:829)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:786)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:703)
    at org.springframework.beans.factory.support.ConstructorResolver.resolveAutowiredArgument(ConstructorResolver.java:795)
    at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:723)
    at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:461)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:983)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:879)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:485)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:456)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:291)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:288)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:190)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:563)
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:895)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:425)
    at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:139)
    at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:93)
    at com.linuxbox.enkive.Main.run(Main.java:54)
    at com.linuxbox.enkive.MainJettyWebApps.main(MainJettyWebApps.java:53)

任何帮助、反馈、想法或建议将不胜感激，如果您需要更多具体信息，请告诉我!

Answer 1

我建议您在执行依赖项注入(inject)后需要立即执行的方法之一上使用@PostConstruct注释。看看这个link了解更多信息。

另一种方法是让您的类实现 ApplicationContextAware 接口(interface)来访问应用程序上下文。有关详细信息，请参阅此 link.

希望这对您有帮助。干杯。