Bean的属性不是通过util:list对象设置的

问题描述

我已经在spring配置文件中使用spring util名称空间声明了以下列表:

I have declared following list using spring util namespace in my spring configuration file:

<util:list id="childList">
        <ref bean="child1"/>
        <ref bean="child2"/>
        <ref bean="child3"/>
</util:list>

，其中所有引用bean均标有@Componant批注，并且正在创建它们各自的bean.但是，每当我尝试自动连线任何bean属性时，例如:

where all reference bean are marked with @Componant annotation and their respective beans are creating. But whenever I am trying to Autowired any beans property like:

@Component
public class ListTest{

@Autowired
@Qualifier("childList")
private List<IParent> list;

public List<IParent> getList() {
    return list;
}

}

给出如下异常:org.springframework.beans.factory.BeanCreationException:创建名称为'listTest'的bean时出错:自动连接依赖项的注入失败；嵌套的异常是org.springframework.beans.factory.BeanCreationException:无法自动装配字段:私有java.util.List com.spring3.componentScanFilterTest.ListTest.list;嵌套的异常是org.springframework.beans.factory.NoSuchBeanDefinitionException:没有找到类型为[com.spring3.componentScanFilterTest.IParent]的匹配bean依赖项[com.spring3.componentScanFilterTest.IParent的集合]:至少需要1个符合以下条件的bean:自动关联此依赖项的候选对象.依赖注释:{@ org.springframework.beans.factory.annotation.Autowired(required = true)，@ org.springframework.beans.factory.annotation.Qualifier(value = childList)}

Gives exception as: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'listTest': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private java.util.List com.spring3.componentScanFilterTest.ListTest.list; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No matching bean of type [com.spring3.componentScanFilterTest.IParent] found for dependency [collection of com.spring3.componentScanFilterTest.IParent]: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true), @org.springframework.beans.factory.annotation.Qualifier(value=childList)}

但是如果我用作@，则不是@Autowired和@Qualifier: @Resource(name ="childList")

But instead of @Autowired and @Qualifier if I use as: @Resource(name="childList")

有效.为什么?据我了解，@ Autowired用于按类型自动匹配匹配的属性，而@Qualifier用于从多个模棱两可的bean中选择任何一个bean.

It works. Why? As per my understanding @Autowired is used to autowire the property matching by type and @Qualifier is used to select any one bean from multiple ambiguous beans.

请解释.

推荐答案

Spring 文档说.

由于这种语义差异的特定结果，本身定义为集合或映射类型的bean无法通过@Autowired注入，因为类型匹配不适用于它们.对此类bean使用@Resource，通过唯一的名称引用特定的collection或map bean.

希望这可以清除您的疑问.

Hope this clear your doubt.

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