按类型将引用bean自动装配到列表中 [英] Autowire reference beans into list by type

问题描述

我有一个类，其中包含守护程序类型的对象列表。

I have one class that has a list of objects of Daemon type.

class Xyz {    
    List<Daemon> daemons;
}

我的弹簧配置如下所示。

My spring configuration looks like this.

<bean id="xyz" class="package1.Xyz">
   <property name="daemons" ref="daemonsList">
</bean>

<bean id="daemon1" class="package1.DaemonImpl1"/>
<bean id="daemon2" class="package1.DaemonImpl2"/>

<bean id="daemonsList" class="java.util.ArrayList">
        <constructor-arg>
            <list>
                <ref bean="daemon1" />      
                <ref bean="daemon2" />
            </list>
        </constructor-arg>
</bean>

现在不是在列表中显式连接每个守护进程实现，而是可以自动装配所有类型的bean 守护程序自动列在列表中。我试图解决的问题是，如果有人创建了一个新的守护程序类实现的bean，并忘记将其连接到列表中。

Now instead of explicitly wiring each daemon implementation in list, is it possible to autowire all beans of type Daemon automatically in list. Problem I am trying to solve is, If someone creates a bean of new implementation of Daemon class and forgets to wire it into list.

我在stackoverflow上的某个地方看到过这个问题，但是无法再找到它。为它道歉。

I have seen this question somewhere on stackoverflow but not able to find that again. Apologies for it.

推荐答案

它应该像这样工作（从你的XML中删除ArrayList bean）：

It should work like this (remove the ArrayList bean from your XML):

public Class Xyz {    

    private List<Daemon> daemons;

    @Autowired
    public void setDaemons(List<Daemon> daemons){
        this.daemons = daemons;
    }

}

我认为没有在XML中执行此操作的方法。

I don't think there's a way to do this in XML.

请参阅：
3.9.2。 @Autowired 和 @Inject ：

See: 3.9.2. @Autowired and @Inject:

还可以通过将注释添加到
期望该类型数组的字段或方法中，从
ApplicationContext提供特定类型的所有bean：

It is also possible to provide all beans of a particular type from the ApplicationContext by adding the annotation to a field or method that expects an array of that type:

public class MovieRecommender {

  @Autowired
  private MovieCatalog[] movieCatalogs;

  // ...
}

同样适用于类型化集合：

The same applies for typed collections:

public class MovieRecommender {

  private Set<MovieCatalog> movieCatalogs;

  @Autowired
  // or if you don't want a setter, annotate the field
  public void setMovieCatalogs(Set<MovieCatalog> movieCatalogs) {
      this.movieCatalogs = movieCatalogs;
  }

  // ...
}

BTW，从Spring 4.x开始，可以使用 @Ordered 机制自动订购这些列表。

BTW, as of Spring 4.x, these lists can be ordered automatically using the @Ordered mechanism.

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