Spring注解 @Configuration
一.@Configuration的作用
二.@Configuration的Spring容器启动方式
三.不加@Configuration的@Bean的解析
四.加@Configuration的@Bean的解析
五.总结与疑问
一.注解作用.
标注在类上，该类会被CGLIB动态代理生成子类，可以达到这样的效果：在某@Bean方法下调用另一个标注了@Bean的方法，得到的会是同一个Bean对象；
@Configuration注解注意点：
1.可以作为Component标签使用；
2.标注的类不能是final类型的（final类无法动态代理生成子类）；
3.注解类里的@Bean对象的id默认是方法名，如果设置了@Bean的name或者value属性，取第一个作为beanId，name中其他的作为别名使用；
4. 标注了@Configuration的类不能是普通内部类，如果非要是个内部类，那就静态内部类也是可以的； 因为普通内部类依赖于外部类的存在；
达到的效果就是这样： 回到解析@Configuration的地方四
获取bean会发现getMan和getMan2对象是同一个对象，去掉Configuration的话就是两个不同的对象
二. 注解形式的Spring容器的启动方式（非Web项目）
方式1. 启动时候将配置类作为参数传入容器，多个配置类也可以一起传入，参数是可变参数类型可以接收多个；
代码语言：javascript复制public class AppConfig1 { @Bean public Man getMan() { Man man = new Man(); man.setName("吕彬彬"); man.setAge(23); return man; } @Bean public Man getMan2() { return getMan(); } public static void main(String[] args) { AnnotationConfigApplicationContext ac = new AnnotationConfigApplicationContext(AppConfig1.class);
//传入的AppConfig1就是配置类，可以不标注@Configuration也能使用 String[] names = ac.getBeanDefinitionNames(); for (String string : names) { System.out.println(string "===" ac.getBean(string)); } ac.close(); }方式2. 空的构造器，之后手动注册配置类，但是记得要调用其refresh方法启动容器；
代码语言：javascript复制 AnnotationConfigApplicationContext ac = new AnnotationConfigApplicationContext(); ac.register(AppConfig1.class); ac.refresh(); String[] names = ac.getBeanDefinitionNames(); for (String string : names) { System.out.println(string "===" ac.getBean(string)); } ac.close();三. 分析不加@Configuration 只是一个启动类就可以解析@Bean注解
3.1 简单绘制下我理解的Spring容器bean的初始化流程：1-2是Spring容器初始化经历的过程，而3-9则是每一个bean创建必经的过程；InstantiationAwareBeanPostProcessor这些特殊的bean处理器如果有就会执行相应的方法；
如果没有 也不影响Bean初始化流程 ；这也是Spring可以丰富扩展的一个点，Spring很多功能Aop、Tx底层就为我们添加了很多这种BFPP、BPP；
AnnotationConfigApplicationContext就为我们添加了这样一个BFPP ConfigurationClassPostProcessor；同样还有很多其他的BFPP、BPP，方法位于AnnotationConfigUtils.registerAnnotationConfigProcessors(this.registry);
ConfigurationClassPostProcessor的类结构图如下，我们只需要看生命周期1、2中的方法即可；
3.2.ConfigurationClassPostProcessor的postProcessBeanDefinitionRegistry方法干了什么呢？
代码语言：javascript复制 1 public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) { //registry就是传入的Spring的基本容器BeanFactory对象，最常见的是DefaultListableBeanFactory 2 int registryId = System.identityHashCode(registry); 3 if (this.registriesPostProcessed.contains(registryId)) { 4 throw new IllegalStateException( 5 "postProcessBeanDefinitionRegistry already called on this post-processor against " registry); 6 } 7 if (this.factoriesPostProcessed.contains(registryId)) { 8 throw new IllegalStateException( 9 "postProcessBeanFactory already called on this post-processor against " registry); 10 } 11 this.registriesPostProcessed.add(registryId); 12 13 processConfigBeanDefinitions(registry);
//Spring给的解释该方法是Build and validate a configuration model based on the registry of Configuration classes. 14 }查看processConfigBeanDefinitions方法
代码语言：javascript复制 1 public void processConfigBeanDefinitions(BeanDefinitionRegistry registry) { 2 List<BeanDefinitionHolder> configCandidates = new ArrayList<>(); 3 String[] candidateNames = registry.getBeanDefinitionNames(); //遍历现有注册的所有bean, 包括了之前的配置类AppConfig1，类型是AnnotatedGenericBeanDefinition 4 5 for (String beanName : candidateNames) { 6 BeanDefinition beanDef = registry.getBeanDefinition(beanName); 7 if (ConfigurationClassUtils.isFullConfigurationClass(beanDef) || 8 ConfigurationClassUtils.isLiteConfigurationClass(beanDef)) {
//判断beanDef有没有CONFIGURATION_CLASS_FULL属性(代表有Configuration注解) CONFIGURATION_CLASS_LITE属性代表有@Bean注解
//只有解析过的beanDef才会有这两种属性 9 if (logger.isDebugEnabled()) { 10 logger.debug("Bean definition has already been processed as a configuration class: " beanDef); 11 } 12 } 13 else if (ConfigurationClassUtils.checkConfigurationClassCandidate(beanDef, this.metadataReaderFactory)) {
//checkConfigurationClassCandidate方法做了以下操作:
// 有@Configuration注解我就给beanDef添加属性CONFIGURATION_CLASS_FULL
// 有@Bean注解我就给beanDef添加属性CONFIGURATION_CLASS_LITE
// 如果两种注解都没有直接返回false,相反有一种都能为true, 就会添加到config候选集合中 14 configCandidates.add(new BeanDefinitionHolder(beanDef, beanName)); 15 } 16 } 17 18 // config候选集合为空直接返回 19 if (configCandidates.isEmpty()) { 20 return; 21 } 46 ....省略代码
47 // Configuration类解析器 48 ConfigurationClassParser parser = new ConfigurationClassParser( 49 this.metadataReaderFactory, this.problemReporter, this.environment, 50 this.resourceLoader, this.componentScanBeanNameGenerator, registry); 51 52 Set<BeanDefinitionHolder> candidates = new LinkedHashSet<>(configCandidates); // config候选集合candidates 53 Set<ConfigurationClass> alreadyParsed = new HashSet<>(configCandidates.size()); 54 do { 55 parser.parse(candidates);
// 开始解析Configuration类，解析过程较为复杂， 简单的针对@Bean对象， parser的configurationClasses集合中添加的ConfigurationClass中持有BeanMethod对象，就是含有@Bean标签的方法 56 parser.validate(); //验证config配置类不能为final类型，还有@Bean方法如果是static的也无需验证 57 58 Set<ConfigurationClass> configClasses = new LinkedHashSet<>(parser.getConfigurationClasses()); 59 configClasses.removeAll(alreadyParsed); 60 62 if (this.reader == null) { 63 this.reader = new ConfigurationClassBeanDefinitionReader( 64 registry, this.sourceExtractor, this.resourceLoader, this.environment, 65 this.importBeanNameGenerator, parser.getImportRegistry()); 66 } 67 this.reader.loadBeanDefinitions(configClasses);
//读取ConfigurationClass的集合，根据BeanMethod来创建ConfigurationClassBeanDefinition，也是一种BeanDefinition对象，不同之处是创建的使用的是factory-method工厂方式创建的
//每个ConfigurationClassBeanDefinition的工厂名就是配置类的ID，工厂方法就是@Bean得方法名；
//同样还有很多处理，比如@Bean的属性设置、init-Method、destroy-Method ; Lazy 、DependsOn等注解的解析 , 还有很多额外的注解的解析就不介绍了；最后解析完成会注册到registry中 68 alreadyParsed.addAll(configClasses); 69 70 candidates.clear(); 71 if (registry.getBeanDefinitionCount() > candidateNames.length) { 72 String[] newCandidateNames = registry.getBeanDefinitionNames(); 73 Set<String> oldCandidateNames = new HashSet<>(Arrays.asList(candidateNames)); 74 Set<String> alreadyParsedClasses = new HashSet<>(); 75 for (ConfigurationClass configurationClass : alreadyParsed) { 76 alreadyParsedClasses.add(configurationClass.getMetadata().getClassName()); 77 } 78 for (String candidateName : newCandidateNames) { 79 if (!oldCandidateNames.contains(candidateName)) { 80 BeanDefinition bd = registry.getBeanDefinition(candidateName); 81 if (ConfigurationClassUtils.checkConfigurationClassCandidate(bd, this.metadataReaderFactory) && 82 !alreadyParsedClasses.contains(bd.getBeanClassName())) { 83 candidates.add(new BeanDefinitionHolder(bd, candidateName)); 84 } 85 } 86 } 87 candidateNames = newCandidateNames; 88 } 89 } 90 while (!candidates.isEmpty()); 93 if (sbr != null && !sbr.containsSingleton(IMPORT_REGISTRY_BEAN_NAME)) { 94 sbr.registerSingleton(IMPORT_REGISTRY_BEAN_NAME, parser.getImportRegistry()); 95 } 97 if (this.metadataReaderFactory instanceof CachingMetadataReaderFactory) { 100 ((CachingMetadataReaderFactory) this.metadataReaderFactory).clearCache(); 101 } 102 }到这里postProcessBeanDefinitionRegistry方法就解析完毕，可以看到没有@Configuration注解的AppConfig1类的@Bean注解的@Bean也注册到Spring容器中了；
结束postProcessBeanDefinitionRegistry 方法时候打印下已经注册的BeanDefinition，可以看到最后两个Bean定义 主要是factoryBeanName以及factoryMethodName属性设置上了
3.3 ConfigurationClassPostProcessor的postProcessBeanFactory方法干了什么呢？
Spring初始化流程图步骤2执行postProcessBeanFactory方法： 其中enhanceConfigurationClasses方法会遍历所有的bean发现没有Configuration注解的bean就结束方法了，所以在这里不分析该方法，后面也会分析的 ：）
代码语言：javascript复制public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) { int factoryId = System.identityHashCode(beanFactory); if (this.factoriesPostProcessed.contains(factoryId)) { throw new IllegalStateException( "postProcessBeanFactory already called on this post-processor against " beanFactory); } this.factoriesPostProcessed.add(factoryId); if (!this.registriesPostProcessed.contains(factoryId)) { // BeanDefinitionRegistryPostProcessor hook apparently not supported... // Simply call processConfigurationClasses lazily at this point then. processConfigBeanDefinitions((BeanDefinitionRegistry) beanFactory); } enhanceConfigurationClasses(beanFactory); beanFactory.addBeanPostProcessor(new ImportAwareBeanPostProcessor(beanFactory)); }下面叙述下这种@Bean转换的ConfigurationClassBeanDefinition怎么实例化： AbstractAutowireCapableBeanFactory的doCreateBean方法 ===> 调用createBeanInstance ===> 发现factoryMethodName不为空，调用instantiateUsingFactoryMethod ===> 最后调用SimpleInstantiationStrategy的instantiate方法；
3.4 没有@Configuration注解下@Bean的实例化
代码语言：javascript复制 public Object instantiate(RootBeanDefinition bd, @Nullable String beanName, BeanFactory owner, @Nullable Object factoryBean, final Method factoryMethod, Object... args) { try { if (System.getSecurityManager() != null) { AccessController.doPrivileged((PrivilegedAction<Object>) () -> { ReflectionUtils.makeAccessible(factoryMethod); return null; }); } else { ReflectionUtils.makeAccessible(factoryMethod); } Method priorInvokedFactoryMethod = currentlyInvokedFactoryMethod.get(); //currentlyInvokedFactoryMethod为ThreadLocal对象，实例化Bean的时候会记录当前的factoryMethod try { currentlyInvokedFactoryMethod.set(factoryMethod); Object result = factoryMethod.invoke(factoryBean, args); //调用反射实例化该@Bean对象 if (result == null) { result = new NullBean(); } return result; } finally { //实例化完成后恢复currentlyInvokedFactoryMethod为之前的值 if (priorInvokedFactoryMethod != null) { currentlyInvokedFactoryMethod.set(priorInvokedFactoryMethod); } else { currentlyInvokedFactoryMethod.remove(); } } } catch (IllegalArgumentException ex) { throw new BeanInstantiationException(factoryMethod, "Illegal arguments to factory method '" factoryMethod.getName() "'; " "args: " StringUtils.arrayToCommaDelimitedString(args), ex); } catch (IllegalAccessException ex) { throw new BeanInstantiationException(factoryMethod, "Cannot access factory method '" factoryMethod.getName() "'; is it public?", ex); } catch (InvocationTargetException ex) { String msg = "Factory method '" factoryMethod.getName() "' threw exception"; if (bd.getFactoryBeanName() != null && owner instanceof ConfigurableBeanFactory && ((ConfigurableBeanFactory) owner).isCurrentlyInCreation(bd.getFactoryBeanName())) { msg = "Circular reference involving containing bean '" bd.getFactoryBeanName() "' - consider " "declaring the factory method as static for independence from its containing instance. " msg; } throw new BeanInstantiationException(factoryMethod, msg, ex.getTargetException()); } }到这里@Bean最简单的创建过程已经分析完成。
四.@Configuration注解下为啥 一 里面得到的@Bean就是同一个对象呢？ 回到效果图地方
前面帮助：其中3.2processConfigBeanDefinitions给标注了@Configuration的配置类设置了属性CONFIGURATION_CLASS_FULL
4.1 查看3.3中没有解析的postProcessBeanFactory的enhanceConfigurationClasses方法
代码语言：javascript复制public void enhanceConfigurationClasses(ConfigurableListableBeanFactory beanFactory) { Map<String, AbstractBeanDefinition> configBeanDefs = new LinkedHashMap<>(); for (String beanName : beanFactory.getBeanDefinitionNames()) { BeanDefinition beanDef = beanFactory.getBeanDefinition(beanName); if (ConfigurationClassUtils.isFullConfigurationClass(beanDef)) {
//遍历了所有的BeanDefinition对象，没有CONFIGURATION_CLASS_FULL就是空的configBeanDefs，方法之前直接返回了； if (!(beanDef instanceof AbstractBeanDefinition)) { throw new BeanDefinitionStoreException("Cannot enhance @Configuration bean definition '" beanName "' since it is not stored in an AbstractBeanDefinition subclass"); } else if (logger.isInfoEnabled() && beanFactory.containsSingleton(beanName)) { logger.info("Cannot enhance @Configuration bean definition '" beanName "' since its singleton instance has been created too early. The typical cause " "is a non-static @Bean method with a BeanDefinitionRegistryPostProcessor " "return type: Consider declaring such methods as 'static'."); } configBeanDefs.put(beanName, (AbstractBeanDefinition) beanDef); //存放标注了Configuration注解的beanDefinition } } if (configBeanDefs.isEmpty()) { return; } ConfigurationClassEnhancer enhancer = new ConfigurationClassEnhancer(); for (Map.Entry<String, AbstractBeanDefinition> entry : configBeanDefs.entrySet()) { AbstractBeanDefinition beanDef = entry.getValue(); // If a @Configuration class gets proxied, always proxy the target class beanDef.setAttribute(AutoProxyUtils.PRESERVE_TARGET_CLASS_ATTRIBUTE, Boolean.TRUE); try { Class<?> configClass = beanDef.resolveBeanClass(this.beanClassLoader); if (configClass != null) { Class<?> enhancedClass = enhancer.enhance(configClass, this.beanClassLoader);
//生成AppConfig1的子类CGLIB代理Class 并且在下面将beanDef类型更改为了该CGLIB class if (configClass != enhancedClass) { if (logger.isTraceEnabled()) { logger.trace(String.format("Replacing bean definition '%s' existing class '%s' with " "enhanced class '%s'", entry.getKey(), configClass.getName(), enhancedClass.getName())); } beanDef.setBeanClass(enhancedClass); } } } catch (Throwable ex) { throw new IllegalStateException("Cannot load configuration class: " beanDef.getBeanClassName(), ex); } } }4.2 既然知道了是采用CGLIB动态代理，那有很多属性需要设置，代理哪些接口，代理的父类类型已经知道了，回调函数、回调函数过滤器设置了哪些？
代码语言：javascript复制 1 private Enhancer newEnhancer(Class<?> configSuperClass, @Nullable ClassLoader classLoader) { 2 Enhancer enhancer = new Enhancer(); 3 enhancer.setSuperclass(configSuperClass); //被代理的父类类型设置上去就是AppConfig1 4 enhancer.setInterfaces(new Class<?>[] {EnhancedConfiguration.class});
//被代理的接口只设置了EnhancedConfiguration，只是为了给CGLIB子类能够设置上BeanFactory属性 5 enhancer.setUseFactory(false); 6 enhancer.setNamingPolicy(SpringNamingPolicy.INSTANCE); 7 enhancer.setStrategy(new BeanFactoryAwareGeneratorStrategy(classLoader)); 8 enhancer.setCallbackFilter(CALLBACK_FILTER); 9 enhancer.setCallbackTypes(CALLBACK_FILTER.getCallbackTypes()); 10 return enhancer; 11 }CALLBACK_FILTER对象如下：
接着利用enhancer对象生成代理子类
代码语言：javascript复制1 private Class<?> createClass(Enhancer enhancer) { 2 Class<?> subclass = enhancer.createClass(); 3 // Registering callbacks statically (as opposed to thread-local) 4 // is critical for usage in an OSGi environment (SPR-5932)... 5 Enhancer.registerStaticCallbacks(subclass, CALLBACKS); //CALLBACKS对象在上面图片里 6 return subclass; 7 }4.3 这样就生成的CGLIB代理的AppConfig对象，相当于AOP增强了该对象，本来AOP增强内的方法调用自身的方法是不能直接增强自身的，那Spring是怎么做的呢？
简单介绍下，Spring CGLIB CallBackFilter的作用； Callback我们都知道是回调方法，CGLIB对象调用方法就会调用回调方法，但是添加了CallBackFilter，他有个方法accpet(Method method)方法用来判断调用的方法，返回值为int类型，代表着走哪个Callback的下标，传入的是个Callback的数组嘛 ：）
代码语言：javascript复制1 public int accept(Method method) { 2 for (int i = 0; i < this.callbacks.length; i ) { 3 Callback callback = this.callbacks[i]; 4 if (!(callback instanceof ConditionalCallback) || ((ConditionalCallback) callback).isMatch(method)) { 5 return i; 6 } 7 } 8 throw new IllegalStateException("No callback available for method " method.getName()); 9 }4.3.1先查看第一个Callback BeanMethodInterceptor
查看其isMatch方法
代码语言：javascript复制 @Override public boolean isMatch(Method candidateMethod) { return (candidateMethod.getDeclaringClass() != Object.class && !BeanFactoryAwareMethodInterceptor.isSetBeanFactory(candidateMethod) && BeanAnnotationHelper.isBeanAnnotated(candidateMethod));
//方法不是Object中定义的，且不是setBeanFactory方法，且该方法包含@Bean注解就返回true }可以发现，只要调用自身的@Bean注解的方法都会走这个BeanMethodInterceptor回调，那我们就不看剩下两个回调函数了，另外一个不做任何操作，一个只是负责给CGLIB对象设置上BeanFactory对象，你说怎么设置，之前CGLIB中就添加了一个实现的接口EnhancedConfiguration，这个接口实现了BeanFactoryAware接口，可以注入BeanFactory对象；
4.3.2 查看 BeanMethodInterceptor的intercept方法
什么时候调用getMan、getMan2方法呢？看到3.4 这样一行 Object result = factoryMethod.invoke(factoryBean, args) 调用反射实例化Bean对象，这个时候不就会走回调方法了吗 ：）
代码语言：javascript复制 1 public Object intercept(Object enhancedConfigInstance, Method beanMethod, Object[] beanMethodArgs, 2 MethodProxy cglibMethodProxy) throws Throwable { 3 4 ConfigurableBeanFactory beanFactory = getBeanFactory(enhancedConfigInstance);
// 通过反射从CGLIB增强的对象获取beanFactory对象 5 String beanName = BeanAnnotationHelper.determineBeanNameFor(beanMethod); // 得到beanName值，默认为方法名字，可以通过@Bean注解指定 6 8 if (BeanAnnotationHelper.isScopedProxy(beanMethod)) { // 解析Scope注解 9 String scopedBeanName = ScopedProxyCreator.getTargetBeanName(beanName); 10 if (beanFactory.isCurrentlyInCreation(scopedBeanName)) { 11 beanName = scopedBeanName; 12 } 13 }
//FactoryBean类型的Bean解析方式，暂不分析
22 if (factoryContainsBean(beanFactory, BeanFactory.FACTORY_BEAN_PREFIX beanName) && 23 factoryContainsBean(beanFactory, beanName)) { 24 Object factoryBean = beanFactory.getBean(BeanFactory.FACTORY_BEAN_PREFIX beanName); 25 if (factoryBean instanceof ScopedProxyFactoryBean) { 26 // Scoped proxy factory beans are a special case and should not be further proxied 27 } 28 else { 29 // It is a candidate FactoryBean - go ahead with enhancement 30 return enhanceFactoryBean(factoryBean, beanMethod.getReturnType(), beanFactory, beanName); 31 } 32 } 33 34 if (isCurrentlyInvokedFactoryMethod(beanMethod)) {
//判断当前执行的方法是否是正在执行的@Bean的方法,getMan2中调用getMan方法,getMan含有@Bean 这时候就返回false 38 if (logger.isInfoEnabled() && 39 BeanFactoryPostProcessor.class.isAssignableFrom(beanMethod.getReturnType())) { 40 logger.info(String.format("@Bean method %s.%s is non-static and returns an object " 41 "assignable to Spring's BeanFactoryPostProcessor interface. This will " 42 "result in a failure to process annotations such as @Autowired, " 43 "@Resource and @PostConstruct within the method's declaring " 44 "@Configuration class. Add the 'static' modifier to this method to avoid " 45 "these container lifecycle issues; see @Bean javadoc for complete details.", 46 beanMethod.getDeclaringClass().getSimpleName(), beanMethod.getName())); 47 } 48 return cglibMethodProxy.invokeSuper(enhancedConfigInstance, beanMethodArgs); //getMan方法直接反射可以得到对象 49 } 50 51 return resolveBeanReference(beanMethod, beanMethodArgs, beanFactory, beanName); //在getMan2中调用getMan方法就会执行这段逻辑 52 通常情况下，比如getMan方法下，会返回true，然后调用反射直接得到Bean对象；而getMan2方法执行的时候调用getMan方法，this对象就是CGLIB对象，就会在走一次这个方法，ThreadLocal对象里存储的是getMan2，当前方法是getMan，就会返回false了，执行resolveBeanReference方法；
代码语言：javascript复制1 private boolean isCurrentlyInvokedFactoryMethod(Method method) { 2 Method currentlyInvoked = SimpleInstantiationStrategy.getCurrentlyInvokedFactoryMethod();
//获取ThreadLocalcurrentlyInvokedFactoryMethod对象currentlyInvokedFactoryMethod中当前的Method 3 return (currentlyInvoked != null && method.getName().equals(currentlyInvoked.getName()) && 4 Arrays.equals(method.getParameterTypes(), currentlyInvoked.getParameterTypes())); 5 }4.3.3 查看resolveBeanReference方法
代码语言：javascript复制 1 private Object resolveBeanReference(Method beanMethod, Object[] beanMethodArgs, 2 ConfigurableBeanFactory beanFactory, String beanName) { 3 8 boolean alreadyInCreation = beanFactory.isCurrentlyInCreation(beanName); //getMan并不是正在创建的bean,false 9 try { 10 if (alreadyInCreation) { 11 beanFactory.setCurrentlyInCreation(beanName, false); 12 } 13 boolean useArgs = !ObjectUtils.isEmpty(beanMethodArgs); 14 if (useArgs && beanFactory.isSingleton(beanName)) { 18 for (Object arg : beanMethodArgs) { 19 if (arg == null) { 20 useArgs = false; 21 break; 22 } 23 } 24 } 25 Object beanInstance = (useArgs ? beanFactory.getBean(beanName, beanMethodArgs) : 26 beanFactory.getBean(beanName)); //没有参数的情况下，直接getBean获取就可以了 27 if (!ClassUtils.isAssignableValue(beanMethod.getReturnType(), beanInstance)) { 28 if (beanInstance.equals(null)) { 29 if (logger.isDebugEnabled()) { 30 logger.debug(String.format("@Bean method %s.%s called as bean reference " 31 "for type [%s] returned null bean; resolving to null value.", 32 beanMethod.getDeclaringClass().getSimpleName(), beanMethod.getName(), 33 beanMethod.getReturnType().getName())); 34 } 35 beanInstance = null; 36 } 37 else { 38 String msg = String.format("@Bean method %s.%s called as bean reference " 39 "for type [%s] but overridden by non-compatible bean instance of type [%s].", 40 beanMethod.getDeclaringClass().getSimpleName(), beanMethod.getName(), 41 beanMethod.getReturnType().getName(), beanInstance.getClass().getName()); 42 try { 43 BeanDefinition beanDefinition = beanFactory.getMergedBeanDefinition(beanName); 44 msg = " Overriding bean of same name declared in: " beanDefinition.getResourceDescription(); 45 } 46 catch (NoSuchBeanDefinitionException ex) { 47 // Ignore - simply no detailed message then. 48 } 49 throw new IllegalStateException(msg); 50 } 51 } 52 Method currentlyInvoked = SimpleInstantiationStrategy.getCurrentlyInvokedFactoryMethod(); //当前ThreadLocal中的是getMan2 53 if (currentlyInvoked != null) { 54 String outerBeanName = BeanAnnotationHelper.determineBeanNameFor(currentlyInvoked); 55 beanFactory.registerDependentBean(beanName, outerBeanName); //设置依赖关系 56 } 57 return beanInstance; 58 } 59 finally { 60 if (alreadyInCreation) { 61 beanFactory.setCurrentlyInCreation(beanName, true); 62 } 63 } 64 }五.总结与疑问
查看CGLIB代理的AppConfig1对象
代码语言：javascript复制1 AnnotationConfigApplicationContext ac = new AnnotationConfigApplicationContext(AppConfig1.class); 2 AppConfig1 config = ac.getBean(AppConfig1.class); 3 Field[] fs = config.getClass().getFields(); 4 for (Field field : fs) { 5 System.out.println(field.getName()); 6 }查看输出：）
总结：@Configuration 可以使 该配置类中 @Bean下方法中如果调用同类的方法 返回的是同一个对象！
疑问？ 突然之间懵逼了，测试一下，会发现@Configuration标注的情况下，this对象指代的是CGLIB代理对象， 我记得Spring Aop的代理对象的this对象不是CGLIB代理对象啊？
所以望知悉的人告知，是this就是CGLIB代理对象还是 SpringAop 作了不透明的封装，this方法调用的时候走父类的方法呢？
解决方法，也算找到问题出在哪里，搞明白其中的道道了 ； 点我查看解决
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