{"id":1521,"date":"2024-09-13T11:47:41","date_gmt":"2024-09-13T03:47:41","guid":{"rendered":"http:\/\/www.spiceandwolf.com.cn\/?p=1521"},"modified":"2024-09-20T15:55:53","modified_gmt":"2024-09-20T07:55:53","slug":"spring-autowired-circularreferences","status":"publish","type":"post","link":"http:\/\/www.spiceandwolf.com.cn\/index.php\/spring-autowired-circularreferences\/","title":{"rendered":"spring\u4f9d\u8d56\u6ce8\u5165\u7684\u5faa\u73af\u4f9d\u8d56\u95ee\u9898"},"content":{"rendered":"\n

\u4e3a\u4ec0\u4e48\u4f1a\u51fa\u73b0\u5faa\u73af\u4f9d\u8d56\u95ee\u9898\uff1f<\/h2>\n\n\n\n

\uff08\u524d\u63d0\u77e5\u8bc6\u70b9\uff1aBean\u7684\u751f\u547d\u5468\u671f\u4f1a\u6709\u56db\u4e2a\u9636\u6bb5\uff0c\u5305\u62ec\u5b9e\u4f8b\u5316\u3001\u5c5e\u6027\u8d4b\u503c\u3001\u521d\u59cb\u5316\u548c\u9500\u6bc1\uff09\u800c\u5728spring\u5bb9\u5668\u4e3b\u51fd\u6570\u8c03\u7528\u7684\u65f6\u5019\u4f1a\u626b\u63cfclass\u6587\u4ef6\u751f\u6210BeanDefinition\u5bf9\u8c61\uff0c\u7136\u540e\u521b\u5efa\u5355\u4f8bbean\u5b58\u50a8\u5230\u5355\u4f8b\u6c60\u4e2d\uff0c\u8fd9\u65f6\u4f1a\u8c03\u7528createBean()\u65b9\u6cd5\uff0c\u800ccreateBean()\u4e2d\u771f\u6b63\u521b\u5efa\u5b9e\u4f8b\u7684\u662fdoCreateBean()\u65b9\u6cd5\uff0cdoCreateBean()\u65b9\u6cd5\u5305\u62ec\u4e86Bean\u751f\u547d\u5468\u671f\u4e2d\u7684\u5b9e\u4f8b\u5316\u3001\u5c5e\u6027\u8d4b\u503c\u3001\u521d\u59cb\u5316\u903b\u8f91\u3002\u5728\u6267\u884c\u5230\u5c5e\u6027\u8d4b\u503cpopulateBean()<\/p>\n\n\n\n

\u65f6\u4f1a\u8fdb\u884c\u4f9d\u8d56\u6ce8\u5165\u64cd\u4f5c\uff0c\u5982\u679c\u5c5e\u6027\u6709@Autowired\u6ce8\u89e3\u4fee\u9970\uff0c\u5219\u4f1a\u8c03\u7528getBean()\u65b9\u6cd5\u5728\u5355\u4f8b\u6c60\u4e2d\u67e5\u627e\u5bf9\u5e94\u7684Bean\u5b9e\u4f8b\uff0c\u5982\u679c\u6ca1\u6709\u5219\u4f1a\u6267\u884ccreateBean()\u521b\u5efa\u5c5e\u6027\u7c7b\u7684\u5b9e\u4f8b\u3002\u8fd9\u65f6\u4e0b\u5217\u573a\u666f\u5c31\u4f1a\u51fa\u73b0\u95ee\u9898\u3002<\/p>\n\n\n\n

\u670d\u52a1A\u6ce8\u5165\u670d\u52a1B\uff1a\u8c03\u7528createBean()\u521b\u5efaA\u5b9e\u4f8b\uff0c\u521b\u5efaA\u5b9e\u4f8b\u65f6\u8c03\u7528A\u7684populateBean()\u4f1agetBean()\uff0c\u7136\u540e\u8c03\u7528createBean()\u521b\u5efaB\u5b9e\u4f8b\u3002<\/p>\n\n\n\n

\u670d\u52a1B\u6ce8\u5165\u670d\u52a1A\uff1a\u8c03\u7528createBean()\u521b\u5efaB\u5b9e\u4f8b\uff0c\u521b\u5efaA\u5b9e\u4f8b\u65f6\u8c03\u7528A\u7684populateBean()\u4f1agetBean()\uff0c\u7136\u540e\u8c03\u7528createBean()\u521b\u5efaB\u5b9e\u4f8b\u3002<\/p>\n\n\n\n

\u8fd9\u5c31\u662f\u5faa\u73af\u4f9d\u8d56\u95ee\u9898\u3002<\/p>\n\n\n\n

\u5982\u4f55\u5224\u65ad\u662f\u5426\u51fa\u73b0\u4e86\u5faa\u73af\u4f9d\u8d56\uff1f<\/h2>\n\n\n\n

spring\u4f1a\u7ef4\u62a4\u4e00\u4e2asingletonsCurrentlyInCreation\u7684Set\u7ed3\u6784\uff0c\u8fd9\u4e2aSet\u7528\u6765\u5b58\u50a8\u5355\u4f8b\u7684beanName\u3002\u901a\u8fc7\u5224\u65ad\u5728singletonsCurrentlyInCreation\u4e2d\u662f\u5426\u5b58\u5728\u5f53\u524dbeanName\u7684\u5143\u7d20\u5373\u53ef\u5224\u65ad\u662f\u5426\u89e6\u53d1\u4e86\u5faa\u73af\u4f9d\u8d56\u3002<\/p>\n\n\n\n

\u8fd9\u4e2aSet\u7ed3\u6784\u6709\u4e09\u4e2a\u5173\u952e\u51fd\u6570\uff1a<\/p>\n\n\n\n

    \/\/ DefaultSingletonBeanRegistry.class\n    \n    public boolean isSingletonCurrentlyInCreation(String beanName) {\n        return this.singletonsCurrentlyInCreation.contains(beanName);\n    }\n\n    protected void beforeSingletonCreation(String beanName) {\n        if (!this.inCreationCheckExclusions.contains(beanName) && !this.singletonsCurrentlyInCreation.add(beanName)) {\n            throw new BeanCurrentlyInCreationException(beanName);\n        }\n    }\n\n    protected void afterSingletonCreation(String beanName) {\n        if (!this.inCreationCheckExclusions.contains(beanName) && !this.singletonsCurrentlyInCreation.remove(beanName)) {\n            throw new IllegalStateException(\"Singleton '\" + beanName + \"' isn't currently in creation\");\n        }\n    }<\/code><\/pre>\n\n\n\n
    \n
  • isSingletonCurrentlyInCreation()\u7528\u6765\u5224\u65ad\u662f\u5426\u89e6\u53d1\u4e86\u5faa\u73af\u4f9d\u8d56\u3002<\/li>\n\n\n\n
  • beforeSingletonCreation()\u5728\u521b\u5efa\u5355\u4f8bbean\u4e4b\u524d\u8c03\u7528\uff0c\u4f5c\u7528\u662f\u5c06\u5f53\u524dbean\u7684beanName\u52a0\u5165\u5230Set\u4e2d\uff08\u5224\u65ad\u662f\u5426\u5faa\u73af\u4f9d\u8d56\u7684\u524d\u63d0\uff09\u3002<\/li>\n\n\n\n
  • afterSingletonCreation()\u5728\u521b\u5efa\u5355\u4f8bbean\u4e4b\u540e\u8c03\u7528\uff0c\u5c06beanName\u4eceSet\u4e2d\u5220\u9664\u3002<\/li>\n<\/ul>\n\n\n\n
    Spring\u5728\u51fa\u73b0\u5faa\u73af\u4f9d\u8d56\u65f6\u4ee3\u7801\u7684\u6267\u884c\u6d41\u7a0b<\/h2>\n\n\n\n
    \u5728\u9610\u8ff0\u6d41\u7a0b\u94b1\u6211\u4eec\u5148\u5c06\u63d0\u4e00\u4e0b\u5faa\u73af\u4f9d\u8d56\u4e2d\u7684\u4e09\u7ea7\u7f13\u5b58\u673a\u5236\uff1a<\/p>\n\n\n\n
      \n
    • singletonObjects\uff08\u4e00\u7ea7\u7f13\u5b58\uff09\u3002\u5355\u4f8b\u6c60\uff0c\u7528\u6765\u5b58\u50a8\u8d70\u5b8c\u5b8c\u6574Bean\u521b\u5efa\u6d41\u7a0b\u7684Bean\u666e\u901a\u5bf9\u8c61\u6216\u8005Bean\u4ee3\u7406\u5bf9\u8c61\u3002<\/li>\n\n\n\n
    • earlySingletonObjects\uff08\u4e8c\u7ea7\u7f13\u5b58\uff09\u3002\u7528\u6765\u5b58\u50a8\u7ecf\u8fc7AOP\u540e\u7684\u52a8\u6001\u53cd\u5c04\u5bf9\u8c61\u3002<\/li>\n\n\n\n
    • singleFactories\uff08\u4e09\u7ea7\u7f13\u5b58\uff09\u3002\u7528\u6765\u5b58\u50a8\u57fa\u4e8ebean\u5bf9\u8c61\u7684\u62c9\u59c6\u8fbe\u8868\u8fbe\u5f0f\u3002<\/li>\n<\/ul>\n\n\n\n
      \u9996\u5148spring\u5bb9\u5668\uff08applicationContext\uff09\u5728\u7cfb\u7edf\u542f\u52a8\u540e\u4f1a\u505a\u8fd9\u4e48\u4e24\u4ef6\u4e8b\u60c5\uff1a<\/p>\n\n\n\n
        \n
      1. \u626b\u63cf\u9879\u76ee\u8f93\u51fa\u76ee\u5f55\u4e2d\u7684class\u6587\u4ef6\uff0c\u5305\u88c5\u6210DefinitionBean\u6570\u636e\u7ed3\u6784\u653e\u5728\u4e00\u4e2amap\u4e2d\u3002<\/li>\n\n\n\n
      2. \u904d\u5386\u6240\u6709\u4f5c\u7528\u57df\u4e3a\u5355\u4f8b\u7684bean\u5bf9\u8c61\uff0c\u521b\u5efa\u5355\u4f8b\u6c60\u3002<\/li>\n<\/ol>\n\n\n\n
        \u800c\u5728\u5355\u4f8b\u521b\u5efa\u8fc7\u7a0b\u4e2d\u6211\u4eec\u5047\u8bbe\u4f1a\u5148\u521b\u5efaAService\u5355\u4f8b\u3002<\/p>\n\n\n\n
        \u521b\u5efaAService\u5355\u4f8b<\/h4>\n\n\n\n
        \u521b\u5efaAService\u5355\u4f8b\u65f6\u4f1a\u8c03\u7528getBean(beanName)\u65b9\u6cd5\u83b7\u53d6\u5355\u4f8bbean\uff0cgetBean()\u591a\u4e2a\u91cd\u8f7d\u65b9\u6cd5\u90fd\u662f\u901a\u8fc7\u8c03\u7528doGetBean()\u65b9\u6cd5\u5b9e\u73b0\u3002<\/p>\n\n\n\n
            \/\/ AbstractBeanFactory.class\n    \n    protected <T> T doGetBean(String name, @Nullable Class<T> requiredType, @Nullable Object[] args, boolean typeCheckOnly) throws BeansException {\n        String beanName = this.transformedBeanName(name);\n        Object sharedInstance = this.getSingleton(beanName);\n        Object bean;\n        if (sharedInstance != null && args == null) {\n            ...\n            bean = this.getObjectForBeanInstance(sharedInstance, name, beanName, (RootBeanDefinition)null);\n        } else {\n            ...\n\n            try {\n                RootBeanDefinition mbd = this.getMergedLocalBeanDefinition(beanName);\n                ...\n\n                \/\/ \u5224\u65ad\u662f\u5426\u662f\u5355\u4f8b\n                if (mbd.isSingleton()) {\n                    \/\/ \u83b7\u53d6\u5355\u4f8b\n                    sharedInstance = this.getSingleton(beanName, () -> {\n                        try {\n                            return this.createBean(beanName, mbd, args);\n                        } catch (BeansException var5) {\n                            this.destroySingleton(beanName);\n                            throw var5;\n                        }\n                    });\n                    bean = this.getObjectForBeanInstance(sharedInstance, name, beanName, mbd);\n                } else if (mbd.isPrototype()) {\n                    ...\n                } else {\n                    ...\n                }\n            } catch (BeansException var26) {\n                this.cleanupAfterBeanCreationFailure(beanName);\n                throw var26;\n            }\n        }\n\n        if (requiredType != null && !requiredType.isInstance(bean)) {\n            ...\n        } else {\n            return bean;\n        }\n    }<\/code><\/pre>\n\n\n\n
        \u5148\u770b\u770bthis.getSingleton(beanName)\u7684\u8fd4\u56de\u7ed3\u679c\uff1a<\/p>\n\n\n\n
            \/\/ DefaultSingletonBeanRegistry.class\n\n    \/\/ \u5f53\u5141\u8bb8\u5faa\u73af\u4f9d\u8d56\uff08allowEarlyReeference\uff09\u65f6\uff0c\u4f1a\u6709\u4e09\u79cd\u53ef\u80fd\u6027\n    \/\/ 1. \u5f53\u4e00\u7ea7\u7f13\u5b58\u4e8c\u7ea7\u7f13\u5b58\u4e2d\u90fd\u6ca1\u6709\u5bf9\u5e94bean\uff0c\u4e14\u6ca1\u6709\u89e6\u53d1\u5faa\u73af\u4f9d\u8d56\uff08\u5373this.isSingletonCurrentlyInCreation\uff09\uff0c\u5219\u8fd4\u56denull\n    \/\/ 2. \u5f53\u4e00\u7ea7\u7f13\u5b58\u4e8c\u7ea7\u7f13\u5b58\u4e2d\u90fd\u6ca1\u6709\u5bf9\u5e94bean\uff0c\u4f46\u662f\u89e6\u53d1\u4e86\u5faa\u73af\u4f9d\u8d56\u65f6\uff0c\u5f53\u4e09\u7ea7\u7f13\u5b58\u4e0d\u4e3a\u7a7a\u65f6\uff0c\u5219\u57fa\u4e8e\u4e09\u7ea7\u7f13\u5b58\u7684\u62c9\u59c6\u8fbe\u8868\u8fbe\u5f0f\u751f\u6210\u5bf9\u5e94\u4ee3\u7406\u5bf9\u8c61\u5e76\u653e\u5230\u4e8c\u7ea7\u7f13\u5b58\u4e2d\uff0c\u5e76\u5220\u9664\u4e09\u7ea7\u7f13\u5b58\u4e2d\u5bf9\u5e94\u7684\u9879\uff08\u8fd9\u91cc\u4f7f\u7528\u4e86\u53cc\u91cd\u68c0\u67e5\u9501\uff09\u3002\n    \/\/ 3. \u5f53\u4e00\u7ea7\u7f13\u5b58\u4e2d\u5b58\u5728\u5bf9\u5e94\u7684bean\uff0c\u5219\u8fd4\u56de\u4e00\u7ea7\u7f13\u5b58\n    \/\/ 4. \u5f53\u4e8c\u7ea7\u7f13\u5b58\u4e2d\u5b58\u5728\u5bf9\u5e94\u7684bean\uff0c\u5219\u8fd4\u56de\u4e8c\u7ea7\u7f13\u5b58\n    protected Object getSingleton(String beanName, boolean allowEarlyReference) {\n        Object singletonObject = this.singletonObjects.get(beanName);\n        if (singletonObject == null && this.isSingletonCurrentlyInCreation(beanName)) {\n            singletonObject = this.earlySingletonObjects.get(beanName);\n            if (singletonObject == null && allowEarlyReference) {\n                synchronized(this.singletonObjects) {\n                    singletonObject = this.singletonObjects.get(beanName);\n                    if (singletonObject == null) {\n                        singletonObject = this.earlySingletonObjects.get(beanName);\n                        if (singletonObject == null) {\n                            ObjectFactory<?> singletonFactory = (ObjectFactory)this.singletonFactories.get(beanName);\n                            if (singletonFactory != null) {\n                                singletonObject = singletonFactory.getObject();\n                                this.earlySingletonObjects.put(beanName, singletonObject);\n                                this.singletonFactories.remove(beanName);\n                            }\n                        }\n                    }\n                }\n            }\n        }\n\n        return singletonObject;\n    }<\/code><\/pre>\n\n\n\n
        \u56e0\u4e3a\u8fd9\u662f\u6ca1\u6709\u4efb\u4f55\u7f13\u5b58\u6570\u636e\u548c\u8f85\u52a9\u6807\u8bb0\u6570\u636e\uff08isSingletonCurrentlyInCreation\uff09\uff0cthis.getSingleton(beanName)\u8fd4\u56denull\u3002<\/p>\n\n\n\n
        \u56e0\u4e3a\u662f\u5355\u4f8b\u6c60\u521b\u5efa\uff0c\u4f1a\u6267\u884cthis.getSingleton(beanName, singletonFactory)\uff1a<\/p>\n\n\n\n
            \/\/ DefaultSingletonBeanRegistry.class\n    \n    public Object getSingleton(String beanName, ObjectFactory<?> singletonFactory) {\n        Assert.notNull(beanName, \"Bean name must not be null\");\n        synchronized(this.singletonObjects) {\n            Object singletonObject = this.singletonObjects.get(beanName);\n            if (singletonObject == null) {\n                ...\n\n                \/\/ \u5c06\u5f53\u524dbeanName\u52a0\u5165\u5230singletonsCurrentlyInCreation\u7684Set\u4e2d\uff0c\u662f\u5224\u65ad\u5faa\u73af\u4f9d\u8d56\u7684\u524d\u63d0\n                this.beforeSingletonCreation(beanName);\n                ...\n\n                try {\n                    singletonObject = singletonFactory.getObject();\n                    ...\n                } catch (IllegalStateException var16) {\n                    ...\n                } catch (BeanCreationException var17) {\n                    ...\n                } finally {\n                    ...\n\n                    \/\/ \u5c06\u5f53\u524dbeanName\u4ecesingletonsCurrentlyInCreation\u5220\u9664\n                    this.afterSingletonCreation(beanName);\n                }\n\n                if (newSingleton) {\n                    this.addSingleton(beanName, singletonObject);\n                }\n            }\n\n            return singletonObject;\n        }\n    }<\/code><\/pre>\n\n\n\n
        \u5165\u53c2\u7684singletonFactory\u5b9e\u5219\u662f\u4e00\u4e2a\u62c9\u59c6\u8fbe\u8868\u8fbe\u5f0f\uff1a<\/p>\n\n\n\n
        () -> {\n    try {\n        return this.createBean(beanName, mbd, args);\n    } catch (BeansException var5) {\n        this.destroySingleton(beanName);\n        throw var5;\n    }\n}<\/code><\/pre>\n\n\n\n
        \u8868\u8fbe\u5f0f\u5185\u4f1a\u8c03\u7528createBean(beanName, mad, args)\u65b9\u6cd5\uff0c\u800ccreateBean\u65b9\u6cd5\u7684\u6838\u5fc3\u5219\u662f\u6211\u4eec\u719f\u77e5\u7684doCreateBean(beanName, mbdToUse, args)\u65b9\u6cd5\uff08\u8be5\u65b9\u6cd5\u4e2d\u5305\u62ec\u4e86bean\u751f\u547d\u5468\u671f\u7684\u4e09\u4e2a\u9636\u6bb5\uff0c\u5373\u5b9e\u4f8b\u5316\u3001\u5c5e\u6027\u8d4b\u503c\u548c\u521d\u59cb\u5316\uff09\uff1a<\/p>\n\n\n\n
            \/\/ AbstractAutowireCapableBeanFactory.class\n\n    protected Object doCreateBean(String beanName, RootBeanDefinition mbd, @Nullable Object[] args) throws BeanCreationException {\n        BeanWrapper instanceWrapper = null;\n        if (mbd.isSingleton()) {\n            instanceWrapper = (BeanWrapper)this.factoryBeanInstanceCache.remove(beanName);\n        }\n\n        \/\/ \u5b9e\u4f8b\u5316\n        if (instanceWrapper == null) {\n            instanceWrapper = this.createBeanInstance(beanName, mbd, args);\n        }\n\n        Object bean = instanceWrapper.getWrappedInstance();\n        ...\n\n        \/\/ \u5224\u65ad\u662f\u5426\u662f\u6b63\u5728\u521b\u5efa\u7684\u5355\u4f8bBean\n        boolean earlySingletonExposure = mbd.isSingleton() && this.allowCircularReferences && this.isSingletonCurrentlyInCreation(beanName);\n        if (earlySingletonExposure) {\n            ...\n\n            \/\/ \u6dfb\u52a0\u5230\u4e09\u7ea7\u7f13\u5b58\n            this.addSingletonFactory(beanName, () -> {\n                return this.getEarlyBeanReference(beanName, mbd, bean);\n            });\n        }\n\n        Object exposedObject = bean;\n\n        try {\n            \/\/ \u5c5e\u6027\u8d4b\u503c\n            this.populateBean(beanName, mbd, instanceWrapper);\n            \/\/ \u521d\u59cb\u5316\n            exposedObject = this.initializeBean(beanName, exposedObject, mbd);\n        } catch (Throwable var18) {\n            if (var18 instanceof BeanCreationException && beanName.equals(((BeanCreationException)var18).getBeanName())) {\n                throw (BeanCreationException)var18;\n            }\n\n            throw new BeanCreationException(mbd.getResourceDescription(), beanName, \"Initialization of bean failed\", var18);\n        }\n\n        ...\n    }<\/code><\/pre>\n\n\n\n
        \u56e0\u4e3a\u5728this.getSingleton(beanName, singletonFactory)\u4e2d\u6211\u4eec\u8c03\u7528\u4e86this.beforeSingletonCreation(beanName)\u65b9\u6cd5\uff0cearlySingletonExposure\u503c\u4e3atrue\uff0c\u6240\u4ee5\u4f1a\u6dfb\u52a0\u5f53\u524dbean\u7684\u4e09\u7ea7\u7f13\u5b58\u3002<\/p>\n\n\n\n
        \u524d\u9762\u90fd\u662f\u94fa\u57ab\uff0c\u5faa\u73af\u4f9d\u8d56\u95ee\u9898\u53d1\u751f\u65f6\u673a\u5c31\u662f\u5c5e\u6027\u8d4b\u503c\u5b9e\u73b0\u4f9d\u8d56\u6ce8\u5165\u65f6\uff0c\u6240\u4ee5\u6211\u4eec\u8981\u5bf9this.populateBean(beanName, mbd, instanceWrapper)\u4e00\u63a2\u7a76\u5c3d\uff1a<\/p>\n\n\n\n
            \/\/ AbstractAutowireCapableBeanFactory.class\n\n    protected void populateBean(String beanName, RootBeanDefinition mbd, @Nullable BeanWrapper bw) {\n        if (bw == null) {\n            ...\n        } else {\n            ...\n            int resolvedAutowireMode = mbd.getResolvedAutowireMode();\n            if (resolvedAutowireMode == 1 || resolvedAutowireMode == 2) {\n                ...\n                if (resolvedAutowireMode == 1) {\n                    this.autowireByName(beanName, mbd, bw, newPvs);\n                }\n\n                if (resolvedAutowireMode == 2) {\n                    this.autowireByType(beanName, mbd, bw, newPvs);\n                }\n\n                ...\n            }\n\n            ...\n        }\n    }<\/code><\/pre>\n\n\n\n
        \u91cd\u70b9\u5173\u6ce8\u4f9d\u8d56\u6ce8\u5165\u65b9\u6cd5this.autowireByName(beanName, mbd, bw, newPvs)\uff1a<\/p>\n\n\n\n
            \/\/ AbstractAutowireCapableBeanFactory.class\n\n    protected void autowireByName(String beanName, AbstractBeanDefinition mbd, BeanWrapper bw, MutablePropertyValues pvs) {\n        String[] propertyNames = this.unsatisfiedNonSimpleProperties(mbd, bw);\n        String[] var6 = propertyNames;\n        int var7 = propertyNames.length;\n\n        for(int var8 = 0; var8 < var7; ++var8) {\n            String propertyName = var6[var8];\n            if (this.containsBean(propertyName)) {\n                \/\/ \u83b7\u53d6bean\u5b9e\u4f8b\n                Object bean = this.getBean(propertyName);\n                pvs.add(propertyName, bean);\n                this.registerDependentBean(propertyName, beanName);\n                ...\n            } else if (this.logger.isTraceEnabled()) {\n                ...\n            }\n        }\n    }<\/code><\/pre>\n\n\n\n
        \u8fd9\u91cc\u4f1a\u904d\u5386bean\u4e2d\u88ab\u88ab@Autowired\u4fee\u9970\u7684\u5c5e\u6027\uff0c\u5982\u679c\u5728BeanDefinitionMap\u4e2d\u6709\u5bf9\u5e94\u7684bean\u6570\u636e\uff0c\u5219\u4f1a\u8c03\u7528getBean(propertyName)\u65b9\u6cd5\u83b7\u53d6bean\u5b9e\u4f8b\uff0c\u8fd9\u65f6\u7ec6\u5fc3\u7684\u540c\u5b66\u5c31\u4f1a\u53d1\u73b0\u8fd9\u4e0d\u5c31\u662f\u521b\u5efaAService\u5355\u4f8b\u65f6\u6700\u521d\u8c03\u7528\u7684\u51fd\u6570\u5417\uff1f\u770b\u6765\u6211\u4eec\u6765\u5230\u4e86\u8fdb\u5165\u4e0b\u4e00\u4e2a\u5faa\u73af\u7684\u8282\u70b9\u2014\u2014\u521b\u5efaBService\u5355\u4f8b\uff08\u5176\u5b9eAService\u5355\u4f8b\u7684\u521b\u5efa\u8fc7\u7a0b\u5e76\u6ca1\u6709\u8d70\u5b8c\uff0c\u4f46\u4f5c\u4e3a\u5faa\u73af\u4f9d\u8d56\u7684\u4e00\u4e2a\u5173\u952e\u8282\u70b9\uff0c\u6211\u4eec\u4f1a\u5728\u540e\u9762\u7684\u5c0f\u8282\u8bf4\u660eAService\u5355\u4f8b\u521b\u5efa\u7684\u540e\u7eed\u64cd\u4f5c\uff09\u3002<\/p>\n\n\n\n
        \u521b\u5efaBService\u5355\u4f8b<\/h4>\n\n\n\n
        …
        \u8f6c\u773c\u95f4\u6211\u4eec\u5c31\u5230\u521b\u5efaBService\u5355\u4f8b\u7684\u5c5e\u6027\u8d4b\u503c\u8fc7\u7a0b\u4e2dthis.autowireByName(beanName, mbd, bw, newPvs)\u65b9\u6cd5\uff08\u524d\u9762\u7684\u8fc7\u7a0b\u8ddf\u521b\u5efaAService\u5355\u4f8b\u5982\u51fa\u4e00\u8f99\uff09\uff0c\u8fd9\u91cc\u6211\u4eec\u53c8\u518d\u6b21\u62ff\u5230AService\u7684beanName\u53bb\u8c03\u7528this.getBean(beanName)\u65b9\u6cd5\uff0c\u4f46\u8fd9\u6b21\u6267\u884c\u7684\u7ed3\u679c\u4f1a\u5927\u4e0d\u76f8\u540c\u3002<\/p>\n\n\n\n
        \u91cd\u8d70\u897f\u6e38\uff0c\u7528AService\u7684beanName\u518d\u6b21\u8c03\u7528getBean(beanName)\u65b9\u6cd5<\/h4>\n\n\n\n
        \u5982\u4e0a\u6587\u6240\u8ff0\uff0cgetBean()\u5e95\u5c42\u8c03\u7528\u4e86doGetBean()\uff0c\u8ba9\u6211\u4eec\u770b\u770b\u8fd9\u6b21\u6267\u884c\u7684\u54ea\u4e00\u4e2a\u5206\u652f\u903b\u8f91\uff1a<\/p>\n\n\n\n
            \/\/ AbstractBeanFactory.class\n\n    protected <T> T doGetBean(String name, @Nullable Class<T> requiredType, @Nullable Object[] args, boolean typeCheckOnly) throws BeansException {\n        String beanName = this.transformedBeanName(name);\n        Object sharedInstance = this.getSingleton(beanName);\n        Object bean;\n        if (sharedInstance != null && args == null) {\n            ...\n            bean = this.getObjectForBeanInstance(sharedInstance, name, beanName, (RootBeanDefinition)null);\n        } else {\n            ...\n\n            try {\n                RootBeanDefinition mbd = this.getMergedLocalBeanDefinition(beanName);\n                ...\n\n                \/\/ \u5224\u65ad\u662f\u5426\u662f\u5355\u4f8b\n                if (mbd.isSingleton()) {\n                    \/\/ \u83b7\u53d6\u5355\u4f8b\n                    sharedInstance = this.getSingleton(beanName, () -> {\n                        try {\n                            return this.createBean(beanName, mbd, args);\n                        } catch (BeansException var5) {\n                            this.destroySingleton(beanName);\n                            throw var5;\n                        }\n                    });\n                    bean = this.getObjectForBeanInstance(sharedInstance, name, beanName, mbd);\n                } else if (mbd.isPrototype()) {\n                    ...\n                } else {\n                    ...\n                }\n            } catch (BeansException var26) {\n                this.cleanupAfterBeanCreationFailure(beanName);\n                throw var26;\n            }\n        }\n\n        if (requiredType != null && !requiredType.isInstance(bean)) {\n            ...\n        } else {\n            return bean;\n        }\n    }<\/code><\/pre>\n\n\n\n
        \u4f1a\u770b\u4e0a\u9762\u5bf9this.getSingleton(beanName)\u7684\u5206\u6790\uff0c\u8fd9\u6b21\u4f1a\u8d70\u7b2c\u4e8c\u6761\u5206\u652f\u903b\u8f91\uff0c\u4f1a\u8fd4\u56deAService\u7684Bean\u4ee3\u7406\u5bf9\u8c61\uff08\u5373\u4e8c\u7ea7\u7f13\u5b58\uff0c\u4e14\u8fd9\u65f6\u53ea\u6709\u4e8c\u7ea7\u7f13\u5b58\u4e2d\u80fd\u67e5\u5230\u5bf9\u5e94\u7684\u5143\u7d20\uff09\uff0c\u8fd9\u91cc\u5c31\u4e0d\u4f1a\u8d70createBean()\u6d41\u7a0b\u800c\u662f\u76f4\u63a5\u8fd4\u56debean\u7684\u4ee3\u7406\u5bf9\u8c61\u4e86\uff0c\u5230\u8fd9\u91cc\u6211\u4eec\u53d1\u73b0\u5176\u5b9e\u5faa\u73af\u4f9d\u8d56\u5df2\u7ecf\u88ab\u89e3\u51b3\u4e86\uff0c\u4f46\u662f\u521b\u5efaAService\u5355\u4f8b\u7684\u521b\u5efa\u8fc7\u7a0b\u5176\u5b9e\u8fd8\u6ca1\u6709\u6267\u884c\u5b8c\uff0c\u6211\u4eec\u7ee7\u7eed\u5f80\u540e\u770b\u4e8c\u7ea7\u7f13\u5b58\u4e2d\u7684\u5bf9\u8c61\u662f\u5982\u4f55\u8fc7\u6e21\u5230\u4e00\u7ea7\u7f13\u5b58\u4e2d\uff08\u5355\u4f8b\u6c60\uff09\u7684\u3002<\/p>\n\n\n\n
        \u4e5d\u4e5d\u5f52\u4e00\uff0c\u5b8c\u6574\u5355\u4f8b\u521b\u5efa\u7684\u540e\u7eed\u64cd\u4f5c<\/h4>\n\n\n\n
        \u672c\u4f8b\u4e2dBService\u5176\u5b9e\u53ea\u662f\u4f5c\u4e3a\u590d\u73b0\u5faa\u73af\u4f9d\u8d56\u573a\u666f\u7684\u4e00\u4e2a\u5de5\u5177\u4eba\uff0c\u6240\u6709\u8fc7\u7a0b\u548cAService\u5355\u4f8b\u521b\u5efa\u76f8\u540c\uff0c\u6240\u4ee5\u6211\u4eec\u8df3\u8fc7\u5b83\u7684\u6267\u884c\u8fc7\u7a0b\uff0c\u76f4\u63a5\u5feb\u8fdb\u5230\u6700\u5916\u5c42\uff08\u5373AService\uff09\u7684createBean(beanName, mad, args)\u8fd4\u56de\u8fd9\u884c\u4ee3\u7801\uff08\u8fd9\u91cc\u5c5e\u6027\u8d4b\u503c\u548c\u521d\u59cb\u5316\u5df2\u7ecf\u6267\u884c\u5b8c\uff09\uff1a<\/p>\n\n\n\n
            \/\/ DefaultSingletonBeanRegistry.class\n\n    public Object getSingleton(String beanName, ObjectFactory<?> singletonFactory) {\n        Assert.notNull(beanName, \"Bean name must not be null\");\n        synchronized(this.singletonObjects) {\n            Object singletonObject = this.singletonObjects.get(beanName);\n            if (singletonObject == null) {\n                ...\n\n                \/\/ \u5c06\u5f53\u524dbeanName\u52a0\u5165\u5230singletonsCurrentlyInCreation\u7684Set\u4e2d\uff0c\u662f\u5224\u65ad\u5faa\u73af\u4f9d\u8d56\u7684\u524d\u63d0\n                this.beforeSingletonCreation(beanName);\n                ...\n\n                try {\n                    singletonObject = singletonFactory.getObject();\n                    newSingleton = true;\n                } catch (IllegalStateException var16) {\n                    ...\n                } catch (BeanCreationException var17) {\n                    ...\n                } finally {\n                    ...\n\n                    \/\/ \u5c06\u5f53\u524dbeanName\u4ecesingletonsCurrentlyInCreation\u5220\u9664\n                    this.afterSingletonCreation(beanName);\n                }\n\n                if (newSingleton) {\n                    this.addSingleton(beanName, singletonObject);\n                }\n            }\n\n            return singletonObject;\n        }\n    }<\/code><\/pre>\n\n\n\n
        createBean()\u65b9\u6cd5\u4f5c\u4e3a\u62c9\u59c6\u8fbe\u8868\u8fbe\u5f0f\u7684\u4e00\u90e8\u5206\uff0csingletonFactory.getObject()\u8fd4\u56de\u7684\u5b9e\u9645\u5c31\u662fcreateBean()\u65b9\u6cd5\u7684\u8fd4\u56de\u503c\uff0c\u5373\u4e8c\u7ea7\u7f13\u5b58\u3002
        \u56e0\u4e3aAService\u5b9e\u4f8b\u521b\u5efa\u57fa\u672c\u7ed3\u675f\uff0c\u8fd9\u91cc\u8c03\u7528this.afterSingletonCreation(beanName)\u5c06beanName\u4ecesingletonCurrentlyInCreation\u4e2d\u5220\u9664\u3002
        \u6700\u540e\u770b\u770bthis.addSingleton(beanName, singletonObject)\u5e72\u4e86\u4ec0\u4e48\uff1a<\/p>\n\n\n\n
            \/\/ DefaultSingletonBeanRegistry.class\n\n    protected void addSingleton(String beanName, Object singletonObject) {\n        synchronized(this.singletonObjects) {\n            this.singletonObjects.put(beanName, singletonObject);\n            this.singletonFactories.remove(beanName);\n            this.earlySingletonObjects.remove(beanName);\n            ...\n        }\n    }<\/code><\/pre>\n\n\n\n
        \u6ca1\u9519\uff0c\u5982\u9884\u6599\u4e00\u6837\u65e0\u8da3\uff0c\u5c31\u662f\u5c06\u4e8c\u7ea7\u7f13\u5b58\u4e2d\u7684bean\u5b9e\u4f8b\u653e\u5230\u4e00\u7ea7\u7f13\u5b58\uff08\u5355\u4f8b\u6c60\uff09\u4e2d\uff0c\u7136\u540e\u5c06\u5176\u4ece\u4e8c\u7ea7\u7f13\u5b58\u548c\u4e09\u7ea7\u7f13\u5b58\u4e2d\u5220\u9664\u3002\u81f3\u6b64\u5faa\u73af\u4f9d\u8d56\u573a\u666f\u4e0bSpring\u7684\u6267\u884c\u5b8c\u6574\u8fc7\u7a0b\u5c31\u8bb2\u89e3\u5b8c\u6bd5\u3002\u540e\u9762\u6211\u4eec\u6d45\u6790\u4e00\u4e0b\u5404\u4e2a\u6570\u636e\u7ed3\u6784\u7684\u4f5c\u7528\u3002<\/p>\n\n\n\n
        spring\u5982\u4f55\u89e3\u51b3\u5faa\u73af\u4f9d\u8d56\u7684\uff1f<\/h2>\n\n\n\n
        \u5e38\u8bf4\u7684\u5faa\u73af\u4f9d\u8d56\u5982\u4f55\u5f62\u6210\u7684\uff08\u5047\u8bbe\u6ca1\u6709\u4e8c\u7ea7\u7f13\u5b58\u548c\u4e09\u7ea7\u7f13\u5b58\u53ca\u76f8\u5173\u903b\u8f91\uff09\uff1f<\/h4>\n\n\n\n
          \n
        1. \u521b\u5efaA\u7684bean\u5b9e\u4f8b\uff08getBean()\u8c03\u7528doGetBean()\uff0cdoGetBean()\u91cc\u9762\u4f1a\u8c03\u7528createBean()\u65b9\u6cd5\uff09\uff0ccreateBean()\u4f1a\u6267\u884c\u5b9e\u4f8b\u5316\u3001\u5c5e\u6027\u8d4b\u503c\u3001\u521d\u59cb\u5316\uff0c\u5728\u5c5e\u6027\u8d4b\u503c\u65f6\u4f1a\u8fdb\u884c\u4f9d\u8d56\u6ce8\u5165\uff0c\u6b64\u65f6\u4f1a\u521b\u5efaB\u7684bean\u5b9e\u4f8b\u3002<\/li>\n\n\n\n
        2. B\u5355\u4f8b\u521b\u5efa\u65f6\u4f9d\u7136\u4f1a\u6267\u884cB\u7684createBean()\u65b9\u6cd5\uff0c\u7136\u540e\u5728b\u7684\u5c5e\u6027\u8d4b\u503c\u65f6\uff0c\u4f1a\u8c03\u7528getBean(beanName)\u65b9\u6cd5\u83b7\u53d6A\u5b9e\u4f8b\u3002<\/li>\n\n\n\n
        3. \u518d\u6b21\u901a\u8fc7getBean(beanName)\u65b9\u6cd5\u83b7\u53d6A\u5b9e\u4f8b\uff0c\u8fd9\u65f6\u5982\u679c\u53ea\u6709\u4e00\u7ea7\u7f13\u5b58\uff0c\u56e0\u4e3a\u6700\u5916\u5c42A\u7684\u5b9e\u4f8b\u521b\u5efa\u8fc7\u7a0b\u6ca1\u6709\u6267\u884c\u5b8c\uff0c\u6240\u4ee5\u4ece\u4e00\u7ea7\u7f13\u5b58\u4e2d\u5e76\u627e\u4e0d\u5230bean\u5bf9\u8c61\uff0c\u4f1a\u518d\u6b21\u6267\u884cA\u5b9e\u4f8b\u7684\u521b\u5efa\u64cd\u4f5c\uff0c\u4ece\u800c\u5f62\u6210\u6b7b\u5faa\u73af\u3002<\/li>\n<\/ol>\n\n\n\n
          \u53ea\u6709\u4e00\u7ea7\u7f13\u5b58\uff0c\u5e76\u4e0d\u80fd\u77e5\u9053\u8fd9\u4e2aBean\u5230\u5e95\u521b\u5efa\u8fc7\u6ca1\u6709\u3002<\/p>\n\n\n\n
          \u4e24\u7ea7\u7f13\u5b58\u80fd\u89e3\u51b3\u5faa\u73af\u4f9d\u8d56\u5417\uff08\u6ca1\u6709\u7b2c\u4e8c\u7ea7\u7f13\u5b58\u53ca\u76f8\u5173\u903b\u8f91\uff09\uff1f<\/h4>\n\n\n\n
          \u4e0d\u884c\uff0c\u5982\u679c\u6709\u591a\u4e2abean\u4e0e\u4e00\u4e2abean\u5f62\u6210\u4e86\u5faa\u73af\u4f9d\u8d56\uff0c\u4f8b\u5982A\u4e0eB\u5f62\u6210\u4e86\u5faa\u73af\u4f9d\u8d56\u7684\u540c\u65f6\u4e5f\u4e0eC\u5f62\u6210\u4e86\u5faa\u73af\u4f9d\u8d56\u3002\u8fd9\u65f6B\u4e0eC\u5728\u5c5e\u6027\u8d4b\u503c\u65f6\u4f1a\u540c\u65f6\u8c03\u7528getBean()\u65b9\u6cd5\u83b7\u53d6\u5355\u4f8b\uff0c\u56e0\u4e3a\u6ca1\u6709\u7b2c\u4e8c\u7ea7\u7f13\u5b58\uff0c\u65e0\u6cd5\u5224\u65ad\u662f\u5426\u5df2\u7ecf\u521b\u5efa\u8fc7\u4ee3\u7406\u5bf9\u8c61\uff0c\u6240\u4ee5\u4e24\u8005\u90fd\u4f1a\u91cd\u65b0\u751f\u6210\u4e00\u4e2abean\u7684\u4ee3\u7406\u5bf9\u8c61\uff0c\u8fd9\u6837\u5c31\u7834\u574f\u4e86\u5355\u4f8b\u4f5c\u7528\u57df\u3002<\/p>\n\n\n\n
          \u5404\u6570\u636e\u7ed3\u6784\u7684\u4f5c\u7528<\/h4>\n\n\n\n
            \n
          • singletonObjects\uff08\u4e00\u7ea7\u7f13\u5b58\uff0c\u5373\u5355\u4f8b\u6c60\uff09\u3002\u5b58\u50a8\u5b8c\u6574\u8d70\u5b8cBean\u751f\u547d\u5468\u671f\u7684bean\u5355\u4f8b\u5bf9\u8c61\u3002<\/li>\n\n\n\n
          • earlySingletonObjects\uff08\u4e8c\u7ea7\u7f13\u5b58\uff09\u3002\u5b58\u50a8\u8fd8\u672a\u5b8c\u5168\u8d70\u5b8cBean\u751f\u547d\u5468\u671f\u7684\u4ee3\u7406\u5bf9\u8c61\u3002\u7528\u6765\u5224\u65ad\u662f\u5426\u5b58\u5728\u5df2\u7ecf\u521b\u5efa\u7684\u4ee3\u7406\u5bf9\u8c61\u5b9e\u4f8b\uff0c\u548c\u83b7\u53d6\u5df2\u7ecf\u521b\u5efa\u7684\u4ee3\u7406\u5bf9\u8c61\u5b9e\u4f8b\u3002<\/li>\n\n\n\n
          • singleFactories\uff08\u4e09\u7ea7\u7f13\u5b58\uff09\u3002\u5b58\u50a8\u5e26\u6709beanName\u548c\u666e\u901abean\u4fe1\u606f\u7684\u62c9\u59c6\u8fbe\u8868\u8fbe\u5f0f\uff0c\u4f5c\u4e3a\u4e00\u4e2abean\u5df2\u7ecf\u5b58\u5728\u5b9e\u4f8b\u7684\u4f9d\u636e\uff0c\u7528\u6765\u6253\u7834\u5faa\u73af\u3002\u7528\u6765\u5224\u65ad\u662f\u5426\u5b58\u5728\u5df2\u7ecf\u521b\u5efa\u7684\u666e\u901abean\u5b9e\u4f8b\uff0c\u548c\u83b7\u53d6\u5df2\u7ecf\u521b\u5efa\u7684\u666e\u901abean\u5b9e\u4f8b\u3002<\/li>\n\n\n\n
          • singletonsCurrentlyInCreation\uff08\u7528\u6765\u5224\u65adbean\u662f\u5426\u5728\u521b\u5efa\u8fc7\u7a0b\u4e2d\uff09\u3002<\/li>\n<\/ul>\n\n\n\n
            \u89e6\u53d1\u5faa\u73af\u4f9d\u8d56\u65f6\u4f1a\u53d1\u751fAOP\u63d0\u524d<\/h2>\n\n\n\n
            \u5f53\u51fa\u73b0\u5faa\u73af\u4f9d\u8d56\u65f6\uff0c\u4f1a\u5c06\u5728\u521d\u59cb\u5316\u8fc7\u7a0b\u4e2d\u7684AOP\u5904\u7406\u8fc7\u7a0b\u63d0\u524d\u5230\u5c5e\u6027\u8d4b\u503c\u4e4b\u524d\u5b9e\u4f8b\u5316\u4e4b\u540e\uff0c\u770b\u770bSpring\u662f\u5982\u4f55\u5b9e\u73b0\u7684\u3002<\/p>\n\n\n\n
            \u63a5\u53e3\u8bbe\u8ba1\u53ca\u5b9e\u73b0<\/h4>\n\n\n\n
            \u5148\u6765\u770b\u770bAOP\u5b9e\u73b0\u7c7b\u53ca\u5176\u63a5\u53e3\u8bbe\u8ba1\uff1a<\/p>\n\n\n\n
            public abstract class AbstractAutoProxyCreator extends ProxyProcessorSupport implements SmartInstantiationAwareBeanPostProcessor, BeanFactoryAware {...}<\/code><\/pre>\n\n\n\n
            \u5b9e\u73b0\u4e86SmartInstantiationAwareBeanPostProcessor\u63a5\u53e3\uff0c\u8fd9\u662f\u5c06\u9700\u8981\u63d0\u524d\u83b7\u53d6\u7684\u8fd9\u79cd\u884c\u4e3a\u4f5c\u4e3a\u89c4\u8303\u62bd\u8c61\u6210\u4e86\u63a5\u53e3\uff1a<\/p>\n\n\n\n
            public interface SmartInstantiationAwareBeanPostProcessor extends InstantiationAwareBeanPostProcessor {\n    @Nullable\n    default Class<?> predictBeanType(Class<?> beanClass, String beanName) throws BeansException {\n        return null;\n    }\n\n    @Nullable\n    default Constructor<?>[] determineCandidateConstructors(Class<?> beanClass, String beanName) throws BeansException {\n        return null;\n    }\n\n    default Object getEarlyBeanReference(Object bean, String beanName) throws BeansException {\n        return bean;\n    }\n}<\/code><\/pre>\n\n\n\n
            \u6211\u4eec\u91cd\u70b9\u5173\u6ce8\u4e0bgetEarlyBeanReference(Object bean, String beanName)\u65b9\u6cd5\u5c31\u884c\u3002<\/p>\n\n\n\n
            \u5f53\u7136\uff0c\u8fd9\u4e2a\u63a5\u53e3\u7684\u7236\u63a5\u53e3\u662f\u7ecf\u5178\u7684\u540e\u7f6e\u5904\u7406\u5668\uff1a<\/p>\n\n\n\n
            public interface InstantiationAwareBeanPostProcessor extends BeanPostProcessor {...}<\/code><\/pre>\n\n\n\n
            \u6240\u4ee5\u9700\u8981\u5b9e\u73b0\u8fd9\u4e24\u4e2a\u65b9\u6cd5\uff1a<\/p>\n\n\n\n
            public interface BeanPostProcessor {\n    @Nullable\n    default Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {\n        return bean;\n    }\n\n    @Nullable\n    default Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {\n        return bean;\n    }\n}<\/code><\/pre>\n\n\n\n
            \u6240\u4ee5\u9700\u8981\u5b9e\u73b0\u8fd9\u4fe9\u65b9\u6cd5\u3002<\/p>\n\n\n\n
            \u8bf4\u4e86\u8fd9\u4e48\u591a\uff0c\u5176\u5b9e\u6700\u4e3b\u8981\u7684\u65b9\u6cd5\u5c31\u53ea\u6709\u51e0\u4e2a\uff1a<\/p>\n\n\n\n
            \/\/ AbstractAutoProxyCreator.class\n\npublic abstract class AbstractAutoProxyCreator extends ProxyProcessorSupport implements SmartInstantiationAwareBeanPostProcessor, BeanFactoryAware {\n    ...\n\n    public Object getEarlyBeanReference(Object bean, String beanName) {\n        Object cacheKey = this.getCacheKey(bean.getClass(), beanName);\n        this.earlyProxyReferences.put(cacheKey, bean);\n        return this.wrapIfNecessary(bean, beanName, cacheKey);\n    }\n\n    ...\n\n    public Object postProcessAfterInitialization(@Nullable Object bean, String beanName) {\n        if (bean != null) {\n            Object cacheKey = this.getCacheKey(bean.getClass(), beanName);\n            if (this.earlyProxyReferences.remove(cacheKey) != bean) {\n                return this.wrapIfNecessary(bean, beanName, cacheKey);\n            }\n        }\n\n        return bean;\n    }\n\n    protected Object getCacheKey(Class<?> beanClass, @Nullable String beanName) {\n        if (StringUtils.hasLength(beanName)) {\n            return FactoryBean.class.isAssignableFrom(beanClass) ? \"&\" + beanName : beanName;\n        } else {\n            return beanClass;\n        }\n    }\n\n    protected Object wrapIfNecessary(Object bean, String beanName, Object cacheKey) {\n        if (StringUtils.hasLength(beanName) && this.targetSourcedBeans.contains(beanName)) {\n            return bean;\n        } else if (Boolean.FALSE.equals(this.advisedBeans.get(cacheKey))) {\n            return bean;\n        } else if (!this.isInfrastructureClass(bean.getClass()) && !this.shouldSkip(bean.getClass(), beanName)) {\n            Object[] specificInterceptors = this.getAdvicesAndAdvisorsForBean(bean.getClass(), beanName, (TargetSource)null);\n            if (specificInterceptors != DO_NOT_PROXY) {\n                this.advisedBeans.put(cacheKey, Boolean.TRUE);\n                Object proxy = this.createProxy(bean.getClass(), beanName, specificInterceptors, new SingletonTargetSource(bean));\n                this.proxyTypes.put(cacheKey, proxy.getClass());\n                return proxy;\n            } else {\n                this.advisedBeans.put(cacheKey, Boolean.FALSE);\n                return bean;\n            }\n        } else {\n            this.advisedBeans.put(cacheKey, Boolean.FALSE);\n            return bean;\n        }\n    }\n\n    ...\n}<\/code><\/pre>\n\n\n\n
              \n
            • getEarlyBeanReference(Object bean, String beanName)\u3002AOP\u63d0\u524d\u65f6\u8c03\u7528\u7684\u5c31\u662f\u8fd9\u4e2a\u65b9\u6cd5\uff0c\u5185\u90e8\u5b9e\u73b0\u548cpostProcessAfterInitialization(@Nullable Object bean, String beanName)\u7c7b\u4f3c\u3002<\/li>\n\n\n\n
            • postProcessAfterInitialization(@Nullable Object bean, String beanName)\u3002\u5f53\u4e0d\u51fa\u73b0\u5faa\u73af\u4f9d\u8d56\u65f6\u6267\u884cAOP\u7684\u65b9\u6cd5\u3002\u5f53\u51fa\u73b0\u5faa\u73af\u4f9d\u8d56\u65f6\uff0c\u56e0\u4e3a\u4e4b\u524d\u7f13\u5b58\u8fc7\u5f53\u524dbean\uff0c\u6240\u4ee5\u4f1a\u8df3\u8fc7\u3002<\/li>\n\n\n\n
            • wrapIfNecessary(Object bean, String beanName, Object cacheKey)\u3002AOP\u5b9e\u73b0\u903b\u8f91\u5728\u8fd9\u4e2a\u65b9\u6cd5\u4e2d\u5b9e\u73b0\u3002<\/li>\n<\/ul>\n\n\n\n
              \u73b0\u5728\u6211\u4eec\u53ea\u9700\u8981getEarlyBeanReference\u548cgetEarlyBeanReference\u65b9\u6cd5\u7684\u8c03\u7528\u65f6\u673a\u5c31\u80fd\u641e\u61c2Spring\u662f\u5982\u4f55\u5c06AOP\u63d0\u524d\u7684\u4e86\u3002<\/p>\n\n\n\n
              AOP\u63d0\u524d\u7684\u5b9e\u73b0\u6d41\u7a0b<\/h4>\n\n\n\n
              \u8fd9\u91cc\u6211\u4eec\u57fa\u4e8e\u5faa\u73af\u4f9d\u8d56\u4e2d\u6267\u884c\u6d41\u7a0b\u7684\u573a\u666f\u4e8b\u4f8b\u6765\u6a21\u62dfAOP\u7684\u5b9e\u73b0\u8fc7\u7a0b\u3002<\/p>\n\n\n\n
              \u9996\u5148\u5728\u521b\u5efaAService\u5355\u4f8b\u65f6\uff0c\u57fa\u4e8e\u8c03\u7528\u94fegetBean()->doGetBean()->createBean()->doCreateBean()\uff0c\u5feb\u8fdb\u5230\u8fd9\uff1a<\/p>\n\n\n\n
                  \/\/ AbstractAutowireCapableBeanFactory.class\n\n    protected Object doCreateBean(String beanName, RootBeanDefinition mbd, @Nullable Object[] args) throws BeanCreationException {\n        BeanWrapper instanceWrapper = null;\n        if (mbd.isSingleton()) {\n            instanceWrapper = (BeanWrapper)this.factoryBeanInstanceCache.remove(beanName);\n        }\n\n        \/\/ \u5b9e\u4f8b\u5316\n        if (instanceWrapper == null) {\n            instanceWrapper = this.createBeanInstance(beanName, mbd, args);\n        }\n\n        Object bean = instanceWrapper.getWrappedInstance();\n        ...\n\n        \/\/ \u5224\u65ad\u662f\u5426\u662f\u6b63\u5728\u521b\u5efa\u7684\u5355\u4f8bBean\n        boolean earlySingletonExposure = mbd.isSingleton() && this.allowCircularReferences && this.isSingletonCurrentlyInCreation(beanName);\n        if (earlySingletonExposure) {\n            ...\n\n            \/\/ \u6dfb\u52a0\u5230\u4e09\u7ea7\u7f13\u5b58\n            this.addSingletonFactory(beanName, () -> {\n                return this.getEarlyBeanReference(beanName, mbd, bean);\n            });\n        }\n\n        Object exposedObject = bean;\n\n        try {\n            \/\/ \u5c5e\u6027\u8d4b\u503c\n            this.populateBean(beanName, mbd, instanceWrapper);\n            \/\/ \u521d\u59cb\u5316\n            exposedObject = this.initializeBean(beanName, exposedObject, mbd);\n        } catch (Throwable var18) {\n            if (var18 instanceof BeanCreationException && beanName.equals(((BeanCreationException)var18).getBeanName())) {\n                throw (BeanCreationException)var18;\n            }\n\n            throw new BeanCreationException(mbd.getResourceDescription(), beanName, \"Initialization of bean failed\", var18);\n        }\n\n        ...\n    }<\/code><\/pre>\n\n\n\n
              \u5728\u4e09\u7ea7\u7f13\u5b58\u4e2d\u6dfb\u52a0\u4e86AbstractAutowireCapableBeanFactory\u7c7bgetEarlyBeanReference(Object bean, String beanName)\u65b9\u6cd5\u7684\u5177\u4f53\u5b9e\u73b0\uff0c\u6211\u4eec\u770b\u770b\u5177\u4f53\u5b9e\u73b0\uff1a<\/p>\n\n\n\n
                  \/\/ AbstractAutowireCapableBeanFactory.class\n    \n    protected Object getEarlyBeanReference(String beanName, RootBeanDefinition mbd, Object bean) {\n        Object exposedObject = bean;\n        if (!mbd.isSynthetic() && this.hasInstantiationAwareBeanPostProcessors()) {\n            Iterator var5 = this.getBeanPostProcessors().iterator();\n\n            while(var5.hasNext()) {\n                BeanPostProcessor bp = (BeanPostProcessor)var5.next();\n                \/\/ \u5b9e\u73b0\u4e86AOP\u63d0\u524d\n                if (bp instanceof SmartInstantiationAwareBeanPostProcessor) {\n                    SmartInstantiationAwareBeanPostProcessor ibp = (SmartInstantiationAwareBeanPostProcessor)bp;\n                    exposedObject = ibp.getEarlyBeanReference(exposedObject, beanName);\n                }\n            }\n        }\n\n        return exposedObject;\n    }<\/code><\/pre>\n\n\n\n
              \u8fd9\u91cc\u904d\u5386\u4e86\u6240\u6709SmartInstantiationAwareBeanPostProcessor\u63a5\u53e3\u7684\u5b9e\u4f8b\u5e76\u8c03\u7528\u4e86getEarlyBeanReference(exposedObject, beanName)\u65b9\u6cd5\uff0c\u8fd9\u4e0b\u6211\u4eec\u77e5\u9053\u4e86AOP\u63d0\u524d\u64cd\u4f5c\u662f\u5728\u54ea\u884c\u4ee3\u7801\u5b9e\u73b0\u7684\u3002<\/p>\n\n\n\n
              \u4f46\u662f\u4e09\u7ea7\u7f13\u5b58\u4e2d\u4fdd\u5b58\u7684\u662f\u62c9\u59c6\u8fbe\u8868\u8fbe\u5f0f\uff0c\u5b9e\u9645\u4e0a\u6dfb\u52a0\u7f13\u5b58\u65f6\u5e76\u6ca1\u6709\u6267\u884c\uff0c\u8fd9\u65f6\u5c31\u6709\u4e24\u79cd\u60c5\u51b5\uff0c\u5982\u679c\u6ca1\u6709\u5faa\u73af\u4f9d\u8d56\uff0c\u90a3\u5c31\u4e00\u76f4\u4e0d\u4f1a\u6267\u884c\uff0c\u5982\u679c\u5b58\u5728\u5faa\u73af\u4f9d\u8d56\uff0c\u5219\u5728\u89e6\u53d1\u5faa\u73af\u4f9d\u8d56\u7684\u77ac\u95f4\u624d\u4f1a\u6267\u884cAOP\uff0c\u5373\u521b\u5efaBService\u5355\u4f8b\u65f6\u7684getBean(BService)->doGetBean()->createBean()->doCreateBean()->populateBean()->getBean(AService)->doGetBean()->getSingleton()<\/p>\n\n\n\n
                  \/\/ DefaultSingletonBeanRegistry.class\n\n    \/\/ \u5f53\u5141\u8bb8\u5faa\u73af\u4f9d\u8d56\uff08allowEarlyReeference\uff09\u65f6\uff0c\u4f1a\u6709\u4e09\u79cd\u53ef\u80fd\u6027\n    \/\/ 1. \u5f53\u4e00\u7ea7\u7f13\u5b58\u4e8c\u7ea7\u7f13\u5b58\u4e2d\u90fd\u6ca1\u6709\u5bf9\u5e94bean\uff0c\u4e14\u6ca1\u6709\u89e6\u53d1\u5faa\u73af\u4f9d\u8d56\uff08\u5373this.isSingletonCurrentlyInCreation\uff09\uff0c\u5219\u8fd4\u56denull\n    \/\/ 2. \u5f53\u4e00\u7ea7\u7f13\u5b58\u4e8c\u7ea7\u7f13\u5b58\u4e2d\u90fd\u6ca1\u6709\u5bf9\u5e94bean\uff0c\u4f46\u662f\u89e6\u53d1\u4e86\u5faa\u73af\u4f9d\u8d56\u65f6\uff0c\u5f53\u4e09\u7ea7\u7f13\u5b58\u4e0d\u4e3a\u7a7a\u65f6\uff0c\u5219\u57fa\u4e8e\u4e09\u7ea7\u7f13\u5b58\u7684\u62c9\u59c6\u8fbe\u8868\u8fbe\u5f0f\u751f\u6210\u5bf9\u5e94\u4ee3\u7406\u5bf9\u8c61\u5e76\u653e\u5230\u4e8c\u7ea7\u7f13\u5b58\u4e2d\uff0c\u5e76\u5220\u9664\u4e09\u7ea7\u7f13\u5b58\u4e2d\u5bf9\u5e94\u7684\u9879\uff08\u8fd9\u91cc\u4f7f\u7528\u4e86\u53cc\u91cd\u68c0\u67e5\u9501\uff09\u3002\n    \/\/ 3. \u5f53\u4e00\u7ea7\u7f13\u5b58\u4e2d\u5b58\u5728\u5bf9\u5e94\u7684bean\uff0c\u5219\u8fd4\u56de\u4e00\u7ea7\u7f13\u5b58\n    \/\/ 4. \u5f53\u4e8c\u7ea7\u7f13\u5b58\u4e2d\u5b58\u5728\u5bf9\u5e94\u7684bean\uff0c\u5219\u8fd4\u56de\u4e8c\u7ea7\u7f13\u5b58\n    protected Object getSingleton(String beanName, boolean allowEarlyReference) {\n        Object singletonObject = this.singletonObjects.get(beanName);\n        if (singletonObject == null && this.isSingletonCurrentlyInCreation(beanName)) {\n            singletonObject = this.earlySingletonObjects.get(beanName);\n            if (singletonObject == null && allowEarlyReference) {\n                synchronized(this.singletonObjects) {\n                    singletonObject = this.singletonObjects.get(beanName);\n                    if (singletonObject == null) {\n                        singletonObject = this.earlySingletonObjects.get(beanName);\n                        if (singletonObject == null) {\n                            ObjectFactory<?> singletonFactory = (ObjectFactory)this.singletonFactories.get(beanName);\n                            if (singletonFactory != null) {\n                                \/\/ \u57fa\u4e8e\u62c9\u59c6\u8fbe\u8868\u8fbe\u5f0f\u751f\u6210\u4e8c\u7ea7\u7f13\u5b58\n                                singletonObject = singletonFactory.getObject();\n                                this.earlySingletonObjects.put(beanName, singletonObject);\n                                this.singletonFactories.remove(beanName);\n                            }\n                        }\n                    }\n                }\n            }\n        }\n\n        return singletonObject;\n    }<\/code><\/pre>\n\n\n\n
              \u6267\u884c\u5230singletonFactory.getObject()\u4ee3\u7801\u65f6\uff0c\u624d\u4f1a\u771f\u6b63\u6267\u884cAOP\u64cd\u4f5c\u5e76\u8fd4\u56de\u4ee3\u7406\u5bf9\u8c61\u3002\u5728BService\u505a\u5c5e\u6027\u8d4b\u503c\u7684\u4f9d\u8d56\u6ce8\u5165\u65f6\u4f1a\u76f4\u63a5\u5c06AService\u7684\u4ee3\u7406\u5bf9\u8c61\u8fd4\u56de\u3002<\/p>\n\n\n\n
              \u6700\u540e\u6211\u4eec\u770b\u770b\u5728\u521b\u5efaAService\u5b9e\u4f8b\u7684\u521d\u59cb\u5316\u9636\u6bb5\uff08getBean()->doGetBean()->createBean()->doCreateBean()->initializeBean()\uff09\u662f\u5982\u4f55\u8df3\u8fc7AOP\u7684\u3002<\/p>\n\n\n\n
              protected Object initializeBean(String beanName, Object bean, @Nullable RootBeanDefinition mbd) {\n        if (System.getSecurityManager() != null) {\n            AccessController.doPrivileged(() -> {\n                this.invokeAwareMethods(beanName, bean);\n                return null;\n            }, this.getAccessControlContext());\n        } else {\n            this.invokeAwareMethods(beanName, bean);\n        }\n\n        Object wrappedBean = bean;\n        if (mbd == null || !mbd.isSynthetic()) {\n            wrappedBean = this.applyBeanPostProcessorsBeforeInitialization(bean, beanName);\n        }\n\n        try {\n            this.invokeInitMethods(beanName, wrappedBean, mbd);\n        } catch (Throwable var6) {\n            throw new BeanCreationException(mbd != null ? mbd.getResourceDescription() : null, beanName, \"Invocation of init method failed\", var6);\n        }\n        \/\/ \u521d\u59cb\u5316\u540e\u7684\u6269\u5c55 \n        if (mbd == null || !mbd.isSynthetic()) {\n            wrappedBean = this.applyBeanPostProcessorsAfterInitialization(wrappedBean, beanName);\n        }\n\n        return wrappedBean;\n    }<\/code><\/pre>\n\n\n\n
              this.applyBeanPostProcessorsAfterInitialization(wrappedBean, beanName)\u8fd9\u4e2a\u65b9\u6cd5\u5b9e\u73b0\u4e86AOP\u64cd\u4f5c\uff1a<\/p>\n\n\n\n
                  public Object applyBeanPostProcessorsAfterInitialization(Object existingBean, String beanName) throws BeansException {\n        Object result = existingBean;\n\n        Object current;\n        for(Iterator var4 = this.getBeanPostProcessors().iterator(); var4.hasNext(); result = current) {\n            BeanPostProcessor processor = (BeanPostProcessor)var4.next();\n            current = processor.postProcessAfterInitialization(result, beanName);\n            if (current == null) {\n                return result;\n            }\n        }\n\n        return result;\n    }<\/code><\/pre>\n\n\n\n
              \u8fd9\u91cc\u4f1a\u8c03\u7528AOP\u5b9e\u73b0\u7c7bAbstractAutoProxyCreator\u7684postProcessAfterInitialization\u65b9\u6cd5\uff08\u524d\u9762\u6709\u5206\u6790\u8fc7\uff09\uff0c\u6240\u4ee5\u8fd9\u91cc\u4f1a\u76f4\u63a5\u8fd4\u56de\u4ee3\u7406\u5bf9\u8c61\u3002\u81f3\u6b64AOP\u63d0\u524d\u7684\u4ee3\u7801\u539f\u7406\u5df2\u7ecf\u5168\u90e8\u89e3\u6790\u5b8c\u6bd5\u3002<\/p>\n\n\n\n
              \u603b\u7ed3<\/h2>\n\n\n\n
                \n
              • \u4e09\u7ea7\u7f13\u5b58\u53ca\u4f5c\u7528\u3002\n
                  \n
                • singletonObjects\uff08\u4e00\u7ea7\u7f13\u5b58\uff09\u3002\u7528\u6765\u5b58\u50a8\u5b8c\u6574\u8d70\u5b8cBean\u751f\u547d\u5468\u671f\u4e2d\u5b9e\u4f8b\u5316\u3001\u5c5e\u6027\u8d4b\u503c\u548c\u521d\u59cb\u5316\u4e09\u4e2a\u9636\u6bb5\u7684\u5355\u4f8b\u3002\u4e00\u7ea7\u7f13\u5b58\u4e3b\u8981\u7528\u6765\u7f13\u5b58\u5355\u4f8b\u5bf9\u8c61\uff0cspring\u57fa\u4e8e\u5b83\u5b9e\u73b0\u4e86\u5355\u4f8b\u6a21\u5f0f\u3002<\/li>\n\n\n\n
                • earlySingletonObjects\uff08\u4e8c\u7ea7\u7f13\u5b58\uff09\u3002\u7528\u6765\u5b58\u50a8\u8fd8\u672a\u5b8c\u5168\u8d70\u5b8cBean\u751f\u547d\u5468\u671f\u7684Bean\u5bf9\u8c61\uff08\u53ef\u80fd\u662f\u666e\u901aBean\u6216\u666e\u901aBean\u7684\u4ee3\u7406\u5bf9\u8c61\uff09\u3002\u4e8c\u7ea7\u7f13\u5b58\u4e3a\u4e86\u4fdd\u8bc1Bean\u5bf9\u8c61\u7684\u5355\u4f8b\u7279\u6027\uff0c\u56e0\u4e3a\u6700\u7ec8\u521b\u5efa\u7684\u5355\u4f8b\u53ef\u80fd\u662f\u666e\u901aBean\u5bf9\u8c61\u4e5f\u53ef\u80fd\u662f\u666e\u901aBean\u7684\u4ee3\u7406\u5bf9\u8c61\u3002<\/li>\n\n\n\n
                • singleFactories\uff08\u4e09\u7ea7\u7f13\u5b58\uff09\u3002\u7528\u6765\u5b58\u50a8\u57fa\u4e8ebean\u7684\u62c9\u59c6\u8fbe\u8868\u8fbe\u5f0f\u3002<\/li>\n<\/ul>\n<\/li>\n\n\n\n
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