Spring IoC和通用接口类型 [英] Spring IoC and Generic Interface Type

问题描述

  public interface ISimpleService< T>< p> {
 void someOp（T t）; 
 T otherOp（）; 
} 
  

Spring可以提供基于泛型类型参数T的IoC吗？我的意思是，像这样：

  public class SpringIocTest {
 @Autowired 
 ISimpleService< Long> longSvc; 
 
 @Autowired 
 ISimpleService< String> strSvc; 
 // ... 
} 
  

当然，不工作：

 期望单个匹配的bean，但找到2：[serviceLong，serviceString] 
 at org.springframework.beans .factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessAfterInstantiation（AutowiredAnnotationBeanPostProcessor.java:243）
 at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean（AbstractAutowireCapableBeanFactory.java:957）
  

我的问题：是否可以通过对Interface或实现类的最小修改来提供类似的功能？我知道例如我可以使用@Qualifiers，但我希望尽可能简单。

解决方案

我不相信这是可能的，因为擦除。我们通常在进行完全自动装配时切换到强类型的子接口：

  public interface LongService extends ISimpleService< Long> {} 
 public interface StringService extends ISimpleService< String> {} 
  

在做这个转换之后，我们发现我们确实很喜欢这个，因为它可以让我们做查找使用情况跟踪效果要好得多，你用泛型界面放松了一些。

I'm trying to use Spring IoC with an interface like this:

public interface ISimpleService<T> {
    void someOp(T t);
    T otherOp();
}

Can Spring provide IoC based on the generic type argument T? I mean, something like this:

public class SpringIocTest {
    @Autowired
    ISimpleService<Long> longSvc;

    @Autowired
    ISimpleService<String> strSvc;
    //...
}

Of course, my example above does not work:

expected single matching bean but found 2: [serviceLong, serviceString]
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessAfterInstantiation(AutowiredAnnotationBeanPostProcessor.java:243)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:957)

My Question: is it possible to provide a similar functionality with minimum modifications to either the Interface or the implementing classes? I know for instance I can use @Qualifiers, but I want to keep things as simple as possible.

解决方案

I do not believe this is possible due to erasure. We generally switched to strongly typed sub-interfaces when going for full-autowiring:

public interface LongService extends ISimpleService<Long> {}
public interface StringService extends ISimpleService<String> {}

Upon doing this switch we found we actually liked this pretty well, because it allows us to do "find usage" tracking much better, something you loose with the generics interfaces.

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