如何在Scala对象中使用Spring自动接线(或手动接线)? [英] How to use Spring Autowired (or manually wired) in Scala object?

问题描述

我正在尝试将Spring与Scala结合使用.我知道Autowired可以与Scala类一起使用，但是我正在使用一个需要对象的Web框架，并且我想向其中注入dao.我不知道该怎么做?抱歉，我对Scala还是陌生的，谢谢.

I am trying to use Spring with Scala. I know Autowired works with Scala class, but I am using a web-framework that requires an object and I want to inject a dao into it. I wonder how to do this? Sorry, I am quite new to Scala, thanks in advance.

    @Service
    object UserRest extends RestHelper {
        @Autowired
        @BeanProperty
        val userRepository: UserRepository = null;

        .....
    }

    <beans>
         .....
         <bean id="userRest" class="com.abc.rest.UserRest" >
              <!--- this is my attempt to manually wire it --->
              <property name="userRepository" ref="userRepository"/>
         </bean>
    </beans>

推荐答案

基本上，您有两个问题:

Basically, you have two problems:

• 属性应该是可变的，即var而不是val

Scala object的所有方法均为static，而Spring需要实例方法.实际上，Scala在幕后创建了一个名为UserRest$的实例方法的类，您需要使它的单例实例UserRest$.MODULE$可用于Spring.
Spring可以将配置应用于预先存在的单例实例，但是它们应该由方法返回，而UserRest$.MODULE$是一个字段.因此，您需要创建一个返回它的方法.

All methods of Scala object are static, whereas Spring expects instance methods. Actually Scala creates a class with instance methods named UserRest$ behind the scene, and you need to make its singleton instance UserRest$.MODULE$ available to Spring.
Spring can apply configuration to preexisting singleton instances, but they should be returned by a method, whereas UserRest$.MODULE$ is a field. Thus, you need to create a method to return it.

因此，类似这样的方法应该起作用:

So, something like this should work:

object UserRest extends RestHelper {
   @BeanProperty
   var userRepository: UserRepository = null;

   def getInstance() = this
   ...
}

.

<bean id="userRest" 
    class="com.abc.rest.UserRest" 
    factory-method = "getInstance">
    <property name="userRepository" ref="userRepository"/>
</bean>

您可以将<property>替换为@Autowired，但由于上述单例实例的问题，因此无法使用@Service替换手动bean声明.

You can replace <property> with @Autowired, but cannot replace manual bean declaration with @Service due to problems with singleton instance described above.

另请参见:

• Scala对象的Java等效项是什么?
• 3.3.2.2使用静态工厂方法实例化

• What is the Java equivalent of a Scala object?
• 3.3.2.2 Instantiation with a static factory method

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