Spring无法自动连线Map bean [英] Spring can't autowire Map bean

问题描述

我已经在春季定义了一个地图：

 < util：map id =AdditionalParamsscope = prototypemap-class =java.util.HashMap
 key-type =java.lang.Stringvalue-type =java.lang.String> 
 
< entry key =Startvalue =12345/> 
< entry key =Finishvalue =12365/> 
< / util：map> 
  

然后我将这个bean自动连接到一个定义为：

  private @Autowired @Qualifier（value =AdditionalParams）Map< String，String> additionalParams; 
  

当这样做时，抛出异常，说：

导致：org.springframework.beans.factory.BeanCreationException：创建名称为DutyCreator的bean时出错：自动连线依赖关系的注入失败;嵌套异常是org.springframework.beans.factory.BeanCreationException：无法自动连线字段：private java.util.Map DutyCreator.additionalParams;嵌套异常是org.springframework.beans.factory.NoSuchBeanDefinitionException：找不到类型为[java.lang.String]的匹配bean，用于依赖关系[值为java.lang.String类型的值]：至少有1个bean符合autowire候选为此依赖。依赖关系注释：{@ org.springframework.beans.factory.annotation.Autowired（required = true），@ org.springframework.beans.factory.annotation.Qualifier（value = AdditionalParams）}

导致：org.springframework.beans.factory.NoSuchBeanDefinitionException：找不到类型为[java.lang.String]的匹配bean，用于依赖关系[值为java.lang.String]的值：至少有一个bean它符合这种依赖性的自动线路候选。依赖关系注释：{@ org.springframework.beans.factory.annotation.Autowired（required = true），@ org.springframework.beans.factory.annotation.Qualifier（value = AdditionalParams）}

<

任何想法？

干杯。

解决方案

从Spring 4.3开始， @Autowired 可以注入列表和映射，该问题中的给定代码将起作用：

说，从4.3开始，可以通过Spring的 @Autowired 类型匹配来匹配收集/映射和数组类型算法，只要元素类型信息保存在 @Bean 中返回类型签名或集合继承层次结构。

但是使用较低的Spring版本，您无法自动连接一个集合在。但是，您可以执行以下操作：

  @Resource（name =AdditionalParams）
 private Map< String，串GT; additionalParams; 
  

甚至：

  @Value（＃{AdditionalParams}）
 private Map< String，String> additionalParams; 
  

检查 spring docs ，提示部分：

自己定义为集合或地图类型的bean不能通过@Autowired注入
，因为类型匹配不适用于
。对此类bean使用@Resource

I've defined a map in spring as such:

<util:map id="AdditionalParams" scope="prototype" map-class="java.util.HashMap" 
          key-type="java.lang.String" value-type="java.lang.String">

    <entry key="Start" value="12345" />
    <entry key="Finish" value="12365" />
</util:map>

And then I'm autowiring this bean to a property defined as:

private @Autowired @Qualifier(value = "AdditionalParams") Map<String, String> additionalParams;

When doing this, the an exception get's thrown saying that:

Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'DutyCreator': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private java.util.Map DutyCreator.additionalParams; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No matching bean of type [java.lang.String] found for dependency [map with value type java.lang.String]: 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=AdditionalParams)}

Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No matching bean of type [java.lang.String] found for dependency [map with value type java.lang.String]: 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=AdditionalParams)}

Any ideas?

Cheers.

解决方案

Starting with Spring 4.3, @Autowired can inject lists and maps and the given code in the question would work:

That said, as of 4.3, collection/map and array types can be matched through Spring’s @Autowired type matching algorithm as well, as long as the element type information is preserved in @Bean return type signatures or collection inheritance hierarchies.

But with a lower Spring version, you can't autowire a collection like that. However, you can do the following:

@Resource(name="AdditionalParams")
private Map<String, String> additionalParams;

or even:

@Value("#{AdditionalParams}")
private Map<String, String> additionalParams;

Check the spring docs, the tips section:

beans that are themselves defined as a collection or map type cannot be injected through @Autowired, because type matching is not properly applicable to them. Use @Resource for such beans

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