spring應用手冊-IOC（XML配置實現）-(36)-context:component-scan的scope-resolver屬性

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context:component-scan的scope-resolver屬性

注意這個屬性scope-resolver和scoped-proxy是互斥的。

這個屬性跟name-generator有點類似，它是基於介面ScopeMetadataResolver的，實現resolveScopeMetadata方法，目的是為了將@Scope(value="",proxyMode=ScopedProxyMode.NO,scopeName="")的配置解析成為一個ScopeMetadata物件,Spring這裡也提供了兩個實現，我們一起看下。首先是org.springframework.context.annotation.AnnotationScopeMetadataResolver中，

public ScopeMetadata resolveScopeMetadata(BeanDefinition definition) {
        ScopeMetadata metadata = new ScopeMetadata();
        if (definition instanceof AnnotatedBeanDefinition) {
            AnnotatedBeanDefinition annDef = (AnnotatedBeanDefinition) definition;
            AnnotationAttributes attributes = AnnotationConfigUtils.attributesFor(annDef.getMetadata(), this.scopeAnnotationType);
            if (attributes != null) {
                metadata.setScopeName(attributes.getAliasedString("value", this.scopeAnnotationType, definition.getSource()));
                ScopedProxyMode proxyMode = attributes.getEnum("proxyMode");
                if (proxyMode == null || proxyMode == ScopedProxyMode.DEFAULT) {
                    proxyMode = this.defaultProxyMode;
                }
                metadata.setScopedProxyMode(proxyMode);
            }
        }
        return metadata;
    }

org.springframework.context.annotation.Jsr330ScopeMetadataResolver中的實現

public ScopeMetadata resolveScopeMetadata(BeanDefinition definition) {
        ScopeMetadata metadata = new ScopeMetadata();
        metadata.setScopeName(BeanDefinition.SCOPE_PROTOTYPE);
        if (definition instanceof AnnotatedBeanDefinition) {
            AnnotatedBeanDefinition annDef = (AnnotatedBeanDefinition) definition;
            Set<String> annTypes = annDef.getMetadata().getAnnotationTypes();
            String found = null;
            for (String annType : annTypes) {
                Set<String> metaAnns = annDef.getMetadata().getMetaAnnotationTypes(annType);
                if (metaAnns.contains("javax.inject.Scope")) {
                    if (found != null) {
                        throw new IllegalStateException("Found ambiguous scope annotations on bean class [" +
                                definition.getBeanClassName() + "]: " + found + ", " + annType);
                    }
                    found = annType;
                    String scopeName = resolveScopeName(annType);
                    if (scopeName == null) {
                        throw new IllegalStateException(
                                "Unsupported scope annotation - not mapped onto Spring scope name: " + annType);
                    }
                    metadata.setScopeName(scopeName);
                }
            }
        }
        return metadata;
    }