spring源码-BeanFactoryPostProcessor-3.2

　　一、BeanFactoryPostProcessor这个是spring容器的拓展之一，其目的是在容器初始化完成之前，通过beanFactory对上下文进行进行操作。

　　二、常用场景，需要对beanDefinition做处理，提供获取bean的方式。基本上涉及到的容器的加载修改，都可以操作。

　　三、实现方式

    public class TestBeanFactoryPostProcessor implements BeanFactoryPostProcessor {

    //这里是要求必须实现的，也是我们操作的地方
    @Override
    public void postProcessBeanFactory(ConfigurableListableBeanFactory configurableListableBeanFactory) throws BeansException {

    }
}

　　说明：这里的ConfigurableListableBeanFactory 也就是我们初始化中用到的DefaultListableBeanFactory

　　四、源码实现

　　　　1）在容器初始化的refresh中实现的方式是

//beanFactory的后置操作
this.invokeBeanFactoryPostProcessors(beanFactory);

　　　　2）invokeBeanFactoryPostProcessors

　　protected void invokeBeanFactoryPostProcessors(ConfigurableListableBeanFactory beanFactory) {
        Set<String> processedBeans = new HashSet();
        Iterator var9;
        ArrayList orderedPostProcessors;
        //这里判断是否是DefaultListableBeanFactory的接口
        if (beanFactory instanceof BeanDefinitionRegistry) {
            BeanDefinitionRegistry registry = (BeanDefinitionRegistry)beanFactory;
            List<BeanFactoryPostProcessor> regularPostProcessors = new LinkedList();
            List<BeanDefinitionRegistryPostProcessor> registryPostProcessors = new LinkedList();
            //获取初始化是否就存在BeanFactoryPostProcessor的类型
            Iterator var7 = this.getBeanFactoryPostProcessors().iterator();

            BeanDefinitionRegistryPostProcessor postProcessor;
            while(var7.hasNext()) {
                BeanFactoryPostProcessor postProcessor = (BeanFactoryPostProcessor)var7.next();
                //如果是BeanDefinitionRegistryPostProcessor注册类型的调用postProcessBeanDefinitionRegistry
                if (postProcessor instanceof BeanDefinitionRegistryPostProcessor) {
                    postProcessor = (BeanDefinitionRegistryPostProcessor)postProcessor;
                    //主要是注册bean的方式，这个是BeanFactoryPostProcessor的子接口
                    postProcessor.postProcessBeanDefinitionRegistry(registry);
                    registryPostProcessors.add(postProcessor);
                } else {
                    //不是BeanDefinitionRegistryPostProcessor类型的直接放入regularPostProcessors
                    regularPostProcessors.add(postProcessor);
                }
            }

            //这里通过getBeansOfType方式加载继承BeanDefinitionRegistryPostProcessor方式的所有bean
            Map<String, BeanDefinitionRegistryPostProcessor> beanMap = beanFactory.getBeansOfType(BeanDefinitionRegistryPostProcessor.class, true, false);
            orderedPostProcessors = new ArrayList(beanMap.values());
            //根据@Order进行排序
            OrderComparator.sort(orderedPostProcessors);
            var9 = orderedPostProcessors.iterator();

            while(var9.hasNext()) {
                postProcessor = (BeanDefinitionRegistryPostProcessor)var9.next();
                //执行相关操作
                postProcessor.postProcessBeanDefinitionRegistry(registry);
            }
            //这里执行对应的后置beanFactory后置操作
            this.invokeBeanFactoryPostProcessors(registryPostProcessors, beanFactory);
            this.invokeBeanFactoryPostProcessors(orderedPostProcessors, beanFactory);
            this.invokeBeanFactoryPostProcessors(regularPostProcessors, beanFactory);
            //添加BeanDefinitionRegistryPostProcessor的bean
            processedBeans.addAll((Collection)beanMap.keySet());
        } else {
            //如果不是DefaultListableBeanFactory(当然还有其他类型)
            this.invokeBeanFactoryPostProcessors(this.getBeanFactoryPostProcessors(), beanFactory);
        }

        //这里才是重点，主要是实现BeanFactoryPostProcessor的接口bean
        String[] postProcessorNames = beanFactory.getBeanNamesForType(BeanFactoryPostProcessor.class, true, false);
        List<BeanFactoryPostProcessor> priorityOrderedPostProcessors = new ArrayList();
        //这里分两种，一中是有序的一中是无序的
        List<String> orderedPostProcessorNames = new ArrayList();
        List<String> nonOrderedPostProcessorNames = new ArrayList();
        String[] var10 = postProcessorNames;
        int var19 = postProcessorNames.length;

        for(int var18 = 0; var18 < var19; ++var18) {
            String ppName = var10[var18];
            if (!processedBeans.contains(ppName)) {
                //匹配对应排序
                if (this.isTypeMatch(ppName, PriorityOrdered.class)) {
                    priorityOrderedPostProcessors.add((BeanFactoryPostProcessor)beanFactory.getBean(ppName, BeanFactoryPostProcessor.class));
                } else if (this.isTypeMatch(ppName, Ordered.class)) {
                    orderedPostProcessorNames.add(ppName);
                } else {
                    //一般使用无序的操作
                    nonOrderedPostProcessorNames.add(ppName);
                }
            }
        }

        //有序的操作
        OrderComparator.sort(priorityOrderedPostProcessors);
        this.invokeBeanFactoryPostProcessors(priorityOrderedPostProcessors, beanFactory);
        orderedPostProcessors = new ArrayList();
        var9 = orderedPostProcessorNames.iterator();

        while(var9.hasNext()) {
            String postProcessorName = (String)var9.next();
            orderedPostProcessors.add((BeanFactoryPostProcessor)this.getBean(postProcessorName, BeanFactoryPostProcessor.class));
        }

        OrderComparator.sort(orderedPostProcessors);
        this.invokeBeanFactoryPostProcessors(orderedPostProcessors, beanFactory);

        //无序的BeanFactoryPostProcessor操作
        List<BeanFactoryPostProcessor> nonOrderedPostProcessors = new ArrayList();
        Iterator var23 = nonOrderedPostProcessorNames.iterator();

        while(var23.hasNext()) {
            String postProcessorName = (String)var23.next();
            nonOrderedPostProcessors.add((BeanFactoryPostProcessor)this.getBean(postProcessorName, BeanFactoryPostProcessor.class));
        }

        this.invokeBeanFactoryPostProcessors(nonOrderedPostProcessors, beanFactory);
    }

    //执行BeanFactoryPostProcessor结构中的postProcessBeanFactory方法
    private void invokeBeanFactoryPostProcessors(Collection<? extends BeanFactoryPostProcessor> postProcessors, ConfigurableListableBeanFactory beanFactory) {
        Iterator var4 = postProcessors.iterator();

        while(var4.hasNext()) {
            BeanFactoryPostProcessor postProcessor = (BeanFactoryPostProcessor)var4.next();
            //实现BeanFactoryPostProcessor的方法可以通过beanFactory进行操作
            postProcessor.postProcessBeanFactory(beanFactory);
        }

    }

　　3）getBeanNamesForType

　　public String[] getBeanNamesForType(Class type, boolean includeNonSingletons, boolean allowEagerInit) {
        List<String> result = new ArrayList();
        //获取beanName
        String[] beanDefinitionNames = this.getBeanDefinitionNames();
        String[] var9 = beanDefinitionNames;
        int var8 = beanDefinitionNames.length;

        for(int var7 = 0; var7 < var8; ++var7) {
            String beanName = var9[var7];
            //检查是否是别名
            if (!this.isAlias(beanName)) {
                try {
                    //获取BeanDefinition
                    RootBeanDefinition mbd = this.getMergedLocalBeanDefinition(beanName);
                    if (!mbd.isAbstract() && (allowEagerInit || (mbd.hasBeanClass() || !mbd.isLazyInit() || this.allowEagerClassLoading) && !this.requiresEagerInitForType(mbd.getFactoryBeanName()))) {
                        boolean isFactoryBean = this.isFactoryBean(beanName, mbd);
                        boolean matchFound = (allowEagerInit || !isFactoryBean || this.containsSingleton(beanName)) && (includeNonSingletons || this.isSingleton(beanName)) && this.isTypeMatch(beanName, type);
                        if (!matchFound && isFactoryBean) {
                            beanName = "&" + beanName;
                            //查看是否匹配
                            matchFound = (includeNonSingletons || mbd.isSingleton()) && this.isTypeMatch(beanName, type);
                        }

                        if (matchFound) {
                            result.add(beanName);
                        }
                    }
                } catch (CannotLoadBeanClassException var13) {
                    if (allowEagerInit) {
                        throw var13;
                    }

                    if (this.logger.isDebugEnabled()) {
                        this.logger.debug("Ignoring bean class loading failure for bean '" + beanName + "'", var13);
                    }

                    this.onSuppressedException(var13);
                } catch (BeanDefinitionStoreException var14) {
                    if (allowEagerInit) {
                        throw var14;
                    }

                    if (this.logger.isDebugEnabled()) {
                        this.logger.debug("Ignoring unresolvable metadata in bean definition '" + beanName + "'", var14);
                    }

                    this.onSuppressedException(var14);
                }
            }
        }

        //查看单例中是否存在
        String[] singletonNames = this.getSingletonNames();
        String[] var18 = singletonNames;
        int var17 = singletonNames.length;

        for(var8 = 0; var8 < var17; ++var8) {
            String beanName = var18[var8];
            if (!this.containsBeanDefinition(beanName)) {
                if (this.isFactoryBean(beanName)) {
                    //查看是否匹配
                    if ((includeNonSingletons || this.isSingleton(beanName)) && this.isTypeMatch(beanName, type)) {
                        result.add(beanName);
                        continue;
                    }

                    beanName = "&" + beanName;
                }

                if (this.isTypeMatch(beanName, type)) {
                    result.add(beanName);
                }
            }
        }

        return StringUtils.toStringArray(result);
    }

    public String[] getBeanDefinitionNames() {
        Map var1 = this.beanDefinitionMap;
        //这里的锁，主要是方式新的bean加入进来
        synchronized(this.beanDefinitionMap) {
            return this.frozenBeanDefinitionNames != null ? this.frozenBeanDefinitionNames : StringUtils.toStringArray(this.beanDefinitionNames);
        }
    }

    public boolean isTypeMatch(String name, Class targetType) throws NoSuchBeanDefinitionException {
        String beanName = this.transformedBeanName(name);
        Class typeToMatch = targetType != null ? targetType : Object.class;
        //在单例中获取
        Object beanInstance = this.getSingleton(beanName, false);
        if (beanInstance != null) {
            if (beanInstance instanceof FactoryBean) {
                if (!BeanFactoryUtils.isFactoryDereference(name)) {
                    Class type = this.getTypeForFactoryBean((FactoryBean)beanInstance);
                    return type != null && typeToMatch.isAssignableFrom(type);
                } else {
                    return typeToMatch.isAssignableFrom(beanInstance.getClass());
                }
            } else {
                return !BeanFactoryUtils.isFactoryDereference(name) && typeToMatch.isAssignableFrom(beanInstance.getClass());
            }
        } else if (this.containsSingleton(beanName) && !this.containsBeanDefinition(beanName)) {
            return false;
        } else {
            BeanFactory parentBeanFactory = this.getParentBeanFactory();
            if (parentBeanFactory != null && !this.containsBeanDefinition(beanName)) {
                return parentBeanFactory.isTypeMatch(this.originalBeanName(name), targetType);
            } else {
                //通过BeanDefinitionHolder方式判定
                RootBeanDefinition mbd = this.getMergedLocalBeanDefinition(beanName);
                BeanDefinitionHolder dbd = mbd.getDecoratedDefinition();
                Class type;
                if (dbd != null && !BeanFactoryUtils.isFactoryDereference(name)) {
                    RootBeanDefinition tbd = this.getMergedBeanDefinition(dbd.getBeanName(), dbd.getBeanDefinition(), mbd);
                    type = this.predictBeanType(dbd.getBeanName(), tbd, FactoryBean.class, typeToMatch);
                    if (type != null && !FactoryBean.class.isAssignableFrom(type)) {
                        //判断是否匹配
                        return typeToMatch.isAssignableFrom(type);
                    }
                }

                Class beanClass = this.predictBeanType(beanName, mbd, FactoryBean.class, typeToMatch);
                if (beanClass == null) {
                    return false;
                } else if (FactoryBean.class.isAssignableFrom(beanClass)) {
                    if (!BeanFactoryUtils.isFactoryDereference(name)) {
                        //通过bean类型进行判断
                        type = this.getTypeForFactoryBean(beanName, mbd);
                        return type != null && typeToMatch.isAssignableFrom(type);
                    } else {
                        return typeToMatch.isAssignableFrom(beanClass);
                    }
                } else {
                    return !BeanFactoryUtils.isFactoryDereference(name) && typeToMatch.isAssignableFrom(beanClass);
                }
            }
        }
    }

　　五、说明(源码部分解说，比较简单。主要是实现过程不复杂，主要是其中的操作，太多了)

　　　　1、BeanFactoryPostProcessor的后置beanFactroy处理主要是在refresh的this.invokeBeanFactoryPostProcessors(beanFactory);上面完成的。

　　　　2、在invokeBeanFactoryPostProcessors中是处理的BeanFactoryPostProcessor的子接口BeanDefinitionRegistryPostProcessor的postProcessBeanDefinitionRegistry方法。

　　　　3、在BeanFactoryPostProcessor的使用过程中使用了2中排序方式PriorityOrder和Order的方式

　　　　4、通过beanFactory的getBeanNamesForType方法，匹配实现BeanFactoryPostProcessor的bean.

　　　　5、在getBeanNamesForType中isTypeMatch是主要匹配类型的关键。

　　　　6、总体来说就是xml解析完成过后，进行的后置beanFactory的处理。