SpringFramework:预期单个匹配的bean，但找到了2 [英] SpringFramework: expected single matching bean but found 2

问题描述

我正在构建一个项目，该项目使用SpringFramework从MongoDB中读取数据，其结构如下所示:存储库和服务:

I'm building a project read data from MongoDB using SpringFramework, with structure for Repository and Service as below:

Repository:
    + Interfaces: 
        - I <T extends Object>
        - I1 extends I<M1>
        - I2 extends I<M2>
    + Implements: 
        - RI Abstract RI<T extends Object>
        - RI1 extends RI<M1> implements I1
        - RI2 extends RI<M2> implements I2

Service:
    + Interfaces: 
        - SI <T extends Object>
        - SI1 extends SI<M1>
        - SI2 extends SI<M1>
    + Implements:
        - Abstract SIIMPL : @Autowired I<?>
        - SI1IMPL : extends SIIMPL<M1> implements SI1
        - SI2IMPL : extends SIIMPL<M2> implements SI2

我跑步时会抛出异常:

没有可用的'I'类型的合格Bean:预期的单个匹配 豆，但发现2:I1，I2

No qualifying bean of type 'I' available: expected single matching bean but found 2: I1,I2

当我删除RI2时，它可以正常工作.我认为，根本原因是@Autowired从Abstract(SIIMPL)到另一个具有 RI1和RI2是2种执行器，因此spring不知道该选择哪个bean.

When I delete RI2, it work properly. In my opinion, I think the root cause is the @Autowired from Abstract(SIIMPL) to another abstract(I) that have 2 implements are RI1 and RI2 so spring does not know what bean to pick.

如果有人有任何想法，请给我评论.谢谢！

If someone have any idea, please leave me a comment. Thank you!

推荐答案

首先，您应该在Abstract SIIMPL类中使用非通配符的泛型.看起来像这样:

Firstly you should use a generics not wildcarding in the Abstract SIIMPL class. So that it looks like:

public abstract class SIIMPL<T> {

   protected I<T> foo; // Don't autowire here

}

然后如上所述，不要将泛型I对象自动连接到抽象类中，只需在那里定义它，然后通过构造函数注入将其自动连接到您的具体类中即可:

Then as above don't autowire the generic I object into the abstract class just define it there and then autowire it into your concrete classes via constuctor injection:

public class SI1IMPL extends SIIMPL<M1> implements ST1 {

  public ST1IMPL(@Autowired I<M1> foo) {
      this.foo = foo;
  }

}

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