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Spring?Boot如何處理@Resource示例分析

更新時(shí)間：2023年07月06日 11:34:24 作者：子瞻

這篇文章主要為大家介紹了Spring?Boot如何處理@Resource示例分析，有需要的朋友可以借鑒參考下，希望能夠有所幫助，祝大家多多進(jìn)步，早日升職加薪

先造一個(gè)測(cè)試用例

public class TransactionServiceTest {
    @Resource
    private IQrcodeAdScheduleService qrcodeAdScheduleService;
}

啟動(dòng)Spring Boot調(diào)用棧信息

圖1

解析@Resource對(duì)應(yīng)的bean信息

由上圖可知，在創(chuàng)建完bean實(shí)例后，通過(guò)applyMergedBeanDefinitionPostProcessors()修改beanDefinition結(jié)構(gòu)(針對(duì)這種場(chǎng)景可以理解為解析@Resource對(duì)應(yīng)的bean信息)

protected void applyMergedBeanDefinitionPostProcessors(RootBeanDefinition mbd, Class<?> beanType, String beanName) {
        for (BeanPostProcessor bp : getBeanPostProcessors()) {
            if (bp instanceof MergedBeanDefinitionPostProcessor) {
                MergedBeanDefinitionPostProcessor bdp = (MergedBeanDefinitionPostProcessor) bp;
                //執(zhí)行CommonAnnotationBeanPostProcessor類(lèi)postProcessMergedBeanDefinition()
                bdp.postProcessMergedBeanDefinition(mbd, beanType, beanName);
            }
        }
    }

圖2

CommonAnnotationBeanPostProcessor

有圖2可知，處理@Resource的PostProcessor是“CommonAnnotationBeanPostProcessor”，然后看一下CommonAnnotationBeanPostProcessor的部分細(xì)節(jié)：

private InjectionMetadata buildResourceMetadata(final Class<?> clazz) {
        LinkedList<InjectionMetadata.InjectedElement> elements = new LinkedList<>();
        Class<?> targetClass = clazz;
        do {
            final LinkedList<InjectionMetadata.InjectedElement> currElements =
                    new LinkedList<>();
            ReflectionUtils.doWithLocalFields(targetClass, field -> {
                if (webServiceRefClass != null && field.isAnnotationPresent(webServiceRefClass)) {
                    if (Modifier.isStatic(field.getModifiers())) {
                        throw new IllegalStateException("@WebServiceRef annotation is not supported on static fields");
                    }
                    currElements.add(new WebServiceRefElement(field, field, null));
                }
                else if (ejbRefClass != null && field.isAnnotationPresent(ejbRefClass)) {
                    if (Modifier.isStatic(field.getModifiers())) {
                        throw new IllegalStateException("@EJB annotation is not supported on static fields");
                    }
                    currElements.add(new EjbRefElement(field, field, null));
                }
                //解析@Resource.class
                else if (field.isAnnotationPresent(Resource.class)) {
                    if (Modifier.isStatic(field.getModifiers())) {
                        throw new IllegalStateException("@Resource annotation is not supported on static fields");
                    }
                    if (!ignoredResourceTypes.contains(field.getType().getName())) {
                        currElements.add(new ResourceElement(field, field, null));
                    }
                }
            });
}

上面的代碼塊出現(xiàn)了期待已久的“Resource.class”關(guān)鍵字，我們就放心了。

我們?cè)倩仡櫼幌拢?br />其流程是這樣的：在AbstractAutowireCapableBeanFactory.populateBean()->ibp.postProcessPropertyValue()->CommonAnnotationBeanPostProcessor.postProcessPropertyValue()去實(shí)例化@Resource作用的bean;

除了和處理@Autowired不是一個(gè)PostProcessor（處理@AutoWireds是用這個(gè)“AutowiredAnnotationBeanPostProcessor”PostProcessor）其他處理流程和@Autowired的處理流程一毛一樣?。?/p>

以上就是Spring Boot如何處理@Resource示例分析的詳細(xì)內(nèi)容，更多關(guān)于Spring Boot處理@Resource的資料請(qǐng)關(guān)注腳本之家其它相關(guān)文章！

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