为什么自动装配对于这个 Spring MVC String bean 属性不起作用？
@Autowired
private String defaultLanguage;
当我尝试使用 @Autowire CountryBean 类的 defaultLanguage 字段时，如下所示：
<beans:bean id="countryBean" class="geoapp.CountryBean">
<beans:property name="defaultLanguage" value="English" />
</beans:bean>
我收到此错误：
Error creating bean with name 'CountryBean':
Injection of autowired dependencies failed;
nested exception is
org.springframework.beans.factory.BeanCreationException:
Could not autowire field:
private java.lang.String geoapp.CountryBean.defaultLanguage;
nested exception is
org.springframework.beans.factory.NoSuchBeanDefinitionException:
No matching bean of type [java.lang.String] found for dependency:
expected at least 1 bean which qualifies as autowire candidate for
this dependency.
Dependency annotations:
{@org.springframework.beans.factory.annotation.Autowired(required=true)}:
当它显示 Nomatching 时找到依赖项 [java.lang.String] 类型的 bean，我想知道是否还需要说一些其他内容来让它知道值 English 是一个 String< /代码>？
@Autowired
private String defaultLanguage;
When I try to @Autowire the defaultLanguage field of the CountryBean class as follows:
<beans:bean id="countryBean" class="geoapp.CountryBean">
<beans:property name="defaultLanguage" value="English" />
</beans:bean>
I get this error:
Error creating bean with name 'CountryBean':
Injection of autowired dependencies failed;
nested exception is
org.springframework.beans.factory.BeanCreationException:
Could not autowire field:
private java.lang.String geoapp.CountryBean.defaultLanguage;
nested exception is
org.springframework.beans.factory.NoSuchBeanDefinitionException:
No matching bean of type [java.lang.String] found for dependency:
expected at least 1 bean which qualifies as autowire candidate for
this dependency.
Dependency annotations:
{@org.springframework.beans.factory.annotation.Autowired(required=true)}:
When it says No matching bean of type [java.lang.String] found for dependency, I wonder if there's something else I need to say to let it know that the value English is a String?
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评论（5）
由于您是通过 xml 显式指定属性值，因此不需要 AutoWired 注释。
Since you are explicitly specifying the property value via xml, there is no need to have the AutoWired annotation.
您没有正确使用自动装配功能。
您可以：
@Autowired注释自动在 Spring 上下文中查找具有您的属性 class 的现有 bean（在您的情况下为String）You are not using the autowire feature properly.
You can either:
<beans:property ... />in the XML and add a setter for the property in the class@Autowiredannotation that automatically looks in the Spring context for an existing bean that has your property class (in your case,String)其他答案是正确的，但为了澄清问题，*.xml 文件中定义的那些 bean 在处理任何 @ 类型注释之前进行处理。因此，对于您的示例，bean“CountryBean”在处理属性“defaultLanguage”之前被处理，从而使依赖项为空。
The other answers are correct, but to clarify things, those beans defined in the *.xml files are processed before any @ type annotations get processed. So for your example, the bean "CountryBean" is processed before the property "defaultLanguage" is processed, leaving the dependency null.
还有一个“其他答案是正确的”，但这里有另一个花絮给你——Spring会自动为你设置枚举，所以如果你有一个语言枚举并且你的bean定义有类似“的东西，你会得到一个类型安全的那里有枚举，而不是字符串。
Yet another 'the other answers are correct', but here's another tidbit for you -- Spring will automatically set enums for you, so if you had an enum of languages and your bean definition had something like ", you'd get a type safe enum in there, instead of a String.
如果您想自动装配您的属性，则需要为该 defaultLanguage 字符串创建一个新 bean。然后将 bean 的名称和字段的名称等同起来。
If you want autowiring your property, you need to make a new bean for that defaultLanguage String. Then equate the bean's name and field's name.