Spring中抽象類中能不能進行＠autoware？

之前做項目中，有時候會突發奇想，這個就是在菜鳥階段想到的，所以對java思想理解的比較低，勿噴。

當時還真發現一些有意思的東西，我們可以思考下，

（1）stackoverflow中的一個答案，說的是，抽象類不能被實例化，需要進行繼承實現；當你去繼承之後，實現了抽象方法時，此時會創建一個匿名類，不是父類的實例化；有多個子類實現時，進行autoware注入，spring不知道which bean去注入；

（2）Abstract classes can』t be instantiated, you need to use a concrete implementation. Same as in regular java, if you try to instantiate an abstract class, it tells you to implement the abstract methods within. When you do, an anonymous class is created. It』s not an instatiation of the abstract class, but a new subclass of that abstract class.

Spring will look for classes which extend your base class, being Report1 and Report2, Spring sees it has multiple classes which match the requirements and doesn』t know which one to choose. thus you get the error that there are multiple matching beans.

You can fix this by making an 「adapter」 basicly create a concrete class which extends your base-class, implements the abstract methods, but doesn』t do anything them. Then you can autowire that implementation and test against it. However your abstract class should allready be tested due to the fact you are testing report 1 and 2. If errors still occur with your base class, it means logic you don』t use is causing bugs, which is a bad practice anyway. also with a test coveage tool you could spot unused code that way.

（3）在抽象類中需要注入（@autowire），在繼承了該抽象類的子類中同樣需要再次注入。比如在項目中用戶購買物品的模板抽象類中需要使用userservice，則在改抽象類中和道具服務類（實現了道具介面並繼承了模板抽象類）均需要對userservice進行注入。

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