java - 枚举到类对象的转换

Question

我获取枚举值作为输入，每个枚举值对应于一个类。 如何定义 spring 配置给定的枚举值应转换为类对象

public enum R {
eR1,
eR2,
eR3;
}

//simple interface
interface R {
    dosomething();
}

//R1 class
class R1 implements R {
    dosomething() {
    //implmentation for R1
    }
}

//R2 class
class R2 implements R {
    dosomething() {
        //implementation for R2
    }
}

我有 API 说，

getR(R er1) {
   //How do I define spring configuration to get class object given enum value??
}

I want to avoid if conditions in API, something like this
getR(R er) {
    if(er.equals(R.eR1)) {
        //do this
    } else if(er.equals(R.eR2)) {
       //do this
    }
}
I want to spring to inject right class based on input parameter so that I can avoid if statement.

假设对于三个枚举字段，我想避免在 spring 中拥有三个 id。

Can I define somethign like this
<bean id="r" class="com.myProject.R1">
    <property name="er1" value="eR1"/>
</bean>
<bean id="r" class="com.myProject.R2">
    <property name="er2" value="eR2"/>
</bean>
//similary for R3 as well

Answer 1

在你的 spring 配置中只需使用枚举值

示例如果你想将 eR2 注入(inject) R2 内，

 <bean id="r2" class="com.myProject.R2">
     <property name="er2" value="eR2"/>
 </bean>

查看示例 here 。您无需使用完全限定名称。请参阅 How assign bean's property an Enum value in Spring config file? 上的讨论.