Spring?Boot?@Autowired?@Resource屬性賦值時機探究

更新時間：2023年07月06日 10:49:27 作者：子瞻

這篇文章主要為大家介紹了Spring?Boot?@Autowired?@Resource屬性賦值時機，有需要的朋友可以借鑒參考下，希望能夠有所幫助，祝大家多多進步，早日升職加薪

@Resource

先貼出測試類

@Service
public class TransactionServiceTest {
    @Resource
    private IQrcodeAdScheduleService qrcodeAdScheduleService;
}

Spring Boot啟動之后調用棧信息

圖1

圖2

由圖1，圖2可知InjectionMetadata.inject()執(zhí)行屬性織入邏輯，下面是部分細節(jié)

protected void inject(Object target, @Nullable String requestingBeanName, @Nullable PropertyValues pvs)
                throws Throwable {
            if (this.isField) {
                Field field = (Field) this.member;
                ReflectionUtils.makeAccessible(field);
                //通過反射對目標target對象也就是我們之前定義的TransactionServiceTest的屬性賦值
                field.set(target, getResourceToInject(target, requestingBeanName));
            }
}

其中，CommonAnnotationBeanPostProcessor.ResourceElement的member屬性存儲的是Filed信息，對于本示例就是：

圖3

@Autowired

對于@Autowired來說，就是AutowiredAnnotationBeanPostProcessor.AutowiredFieldElement.inject()：

protected void inject(Object bean, @Nullable String beanName, @Nullable PropertyValues pvs) throws Throwable {
            Field field = (Field) this.member;
            Object value;
            if (this.cached) {
                value = resolvedCachedArgument(beanName, this.cachedFieldValue);
            }
            else {
                DependencyDescriptor desc = new DependencyDescriptor(field, this.required);
                desc.setContainingClass(bean.getClass());
                Set<String> autowiredBeanNames = new LinkedHashSet<>(1);
                Assert.state(beanFactory != null, "No BeanFactory available");
                TypeConverter typeConverter = beanFactory.getTypeConverter();
                try {
                    //遞歸調用createBean()實例化目標bean的屬性bean實例
                    value = beanFactory.resolveDependency(desc, beanName, autowiredBeanNames, typeConverter);
                }
                catch (BeansException ex) {
                    throw new UnsatisfiedDependencyException(null, beanName, new InjectionPoint(field), ex);
                }
                synchronized (this) {
                    if (!this.cached) {
                        if (value != null || this.required) {
                            this.cachedFieldValue = desc;
                            registerDependentBeans(beanName, autowiredBeanNames);
                            if (autowiredBeanNames.size() == 1) {
                                String autowiredBeanName = autowiredBeanNames.iterator().next();
                                if (beanFactory.containsBean(autowiredBeanName) &&
                                        beanFactory.isTypeMatch(autowiredBeanName, field.getType())) {
                                    this.cachedFieldValue = new ShortcutDependencyDescriptor(
                                            desc, autowiredBeanName, field.getType());
                                }
                            }
                        }
                        else {
                            this.cachedFieldValue = null;
                        }
                        this.cached = true;
                    }
                }
            }
            if (value != null) {
                //通過field進行賦值
                ReflectionUtils.makeAccessible(field);
                field.set(bean, value);
            }
        }
}

其他的流程一毛一樣啊～

以上就是Spring Boot @Autowired @Resource屬性賦值時機探究的詳細內容，更多關于SpringBoot @Autowired @Resource的資料請關注腳本之家其它相關文章！

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