java - 如何在 Spring 中自动装配静态字段时使用 @Lazy

Question

我正在尝试在 Spring 中自动装配一个静态字段。我正在使用以下代码来做到这一点：

public static String STATIC_FIELD= "default_value";
    @Autowired
    @Lazy
    public void setStaticProperty(
            @Value("${property.xx.xxx}") final String property) {
        STATIC_FIELD= property;
    }

此代码是在应用程序运行期间创建的组件类的一部分。我不希望在创建 bean 期间设置此字段，并希望它延迟初始化。上面的代码抛出以下错误：

2018-12-17 08:12:42 [main] ERROR o.s.boot.SpringApplication - Application run failed
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'foobar': Injection of autowired dependencies failed; nested exception is org.springframework.aop.framework.AopConfigException: Could not generate CGLIB subclass of class java.lang.String: Common causes of this problem include using a final class or a non-visible class; nested exception is java.lang.IllegalArgumentException: Cannot subclass final class java.lang.String
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessProperties(AutowiredAnnotationBeanPostProcessor.java:380)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1378)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:575)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:498)
    at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:320)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:318)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:846)
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:863)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:546)
    at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:142)
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:775)
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:316)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1260)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1248)
    at com.oracle.athena.aggregator.AggregatorApplication.main(AggregatorApplication.java:78)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.springframework.boot.loader.MainMethodRunner.run(MainMethodRunner.java:48)
    at org.springframework.boot.loader.Launcher.launch(Launcher.java:87)
    at org.springframework.boot.loader.Launcher.launch(Launcher.java:50)
    at org.springframework.boot.loader.JarLauncher.main(JarLauncher.java:51)
Caused by: org.springframework.aop.framework.AopConfigException: Could not generate CGLIB subclass of class java.lang.String: Common causes of this problem include using a final class or a non-visible class; nested exception is java.lang.IllegalArgumentException: Cannot subclass final class java.lang.String
    at org.springframework.aop.framework.CglibAopProxy.getProxy(CglibAopProxy.java:208)
    at org.springframework.aop.framework.ProxyFactory.getProxy(ProxyFactory.java:110)
    at org.springframework.context.annotation.ContextAnnotationAutowireCandidateResolver.buildLazyResolutionProxy(ContextAnnotationAutowireCandidateResolver.java:117)
    at org.springframework.context.annotation.ContextAnnotationAutowireCandidateResolver.getLazyResolutionProxyIfNecessary(ContextAnnotationAutowireCandidateResolver.java:52)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1161)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredMethodElement.inject(AutowiredAnnotationBeanPostProcessor.java:668)
    at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:90)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessProperties(AutowiredAnnotationBeanPostProcessor.java:374)
    ... 25 common frames omitted
Caused by: java.lang.IllegalArgumentException: Cannot subclass final class java.lang.String
    at org.springframework.cglib.proxy.Enhancer.generateClass(Enhancer.java:657)
    at org.springframework.cglib.transform.TransformingClassGenerator.generateClass(TransformingClassGenerator.java:33)
    at org.springframework.cglib.core.DefaultGeneratorStrategy.generate(DefaultGeneratorStrategy.java:25)
    at org.springframework.aop.framework.CglibAopProxy$ClassLoaderAwareUndeclaredThrowableStrategy.generate(CglibAopProxy.java:1007)
    at org.springframework.cglib.core.AbstractClassGenerator.generate(AbstractClassGenerator.java:354)
    at org.springframework.cglib.proxy.Enhancer.generate(Enhancer.java:582)
    at org.springframework.cglib.core.AbstractClassGenerator$ClassLoaderData$3.apply(AbstractClassGenerator.java:106)
    at org.springframework.cglib.core.AbstractClassGenerator$ClassLoaderData$3.apply(AbstractClassGenerator.java:104)
    at org.springframework.cglib.core.internal.LoadingCache$2.call(LoadingCache.java:54)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at org.springframework.cglib.core.internal.LoadingCache.createEntry(LoadingCache.java:61)
    at org.springframework.cglib.core.internal.LoadingCache.get(LoadingCache.java:34)
    at org.springframework.cglib.core.AbstractClassGenerator$ClassLoaderData.get(AbstractClassGenerator.java:130)
    at org.springframework.cglib.core.AbstractClassGenerator.create(AbstractClassGenerator.java:315)
    at org.springframework.cglib.proxy.Enhancer.createHelper(Enhancer.java:569)
    at org.springframework.cglib.proxy.Enhancer.createClass(Enhancer.java:416)
    at org.springframework.aop.framework.ObjenesisCglibAopProxy.createProxyClassAndInstance(ObjenesisCglibAopProxy.java:58)
    at org.springframework.aop.framework.CglibAopProxy.getProxy(CglibAopProxy.java:205)
    ... 32 common frames omitted

自动装配静态字段时是否有任何正确的方法来使用@Lazy？

编辑：我知道自动装配静态方法是不好的设计，不推荐但是我正在寻找一个选项来实现这个（https://stackoverflow.com/a/5991240/6509158）并带有延迟加载选项。对于我当前的代码，一旦我在方法顶部添加了 @Lazy 注释，我就会收到上述错误。我的问题是有什么办法可以解决这个问题，还是有其他方法我应该接近？先感谢您！

标签： javaspring-bootlazy-loadingautowired