Spring 限定符和属性占位符 [英] Spring Qualifier and property placeholder

问题描述

有谁知道我是否应该能够在限定符中使用属性占位符作为表达式?我似乎无法正常工作.

Does anyone know if I should be able to use property placeholder as an expression in a Qualifier? I can't seem to get this working.

我使用的是 spring 3.0.4.

I am using spring 3.0.4.

@Controller
public class MyController {
   @Autowired
   @Qualifier("${service.class}")
   Service service;
}

@Service
@Qualifier("ServiceA")
ServiceA implements Service {
   public void print() {
       System.out.println("printing ServiceA.print()");
   } 
}

@Service
@Qualifier("ServiceB")
ServiceB implements Service {
   public void print() {
      System.out.println("printing ServiceB.print()");
   } 
}

XML:

<bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
        <property name="location" value="file:/etc/config.properties"/>
</bean>

config.properties:

config.properties:

config.properties
service.class=serviceB

推荐答案

这有效.如果您只使用默认的 spring bean 名称，则可以不使用服务名称.serviceA vs ServiceA 等

This works. You can leave off the service names if you just use the default spring bean name. serviceA vs ServiceA, etc.

@Controller
class MyController {
@Autowired(required=false)
@Qualifier("Service")
Service service;

public static void main(String[] args) {
   ApplicationContext context = new ClassPathXmlApplicationContext("app-ctx.xml", MyController.class);
   for(String s:context.getBeanDefinitionNames()){
       System.out.println(s);
       for(String t:context.getAliases(s)){
           System.out.println("	" + t);
       }
   }
   context.getBean(MyController.class).service.print();
  }
}

public interface Service {
    void print();
}

@Service(value="ServiceA")
public class ServiceA implements example.Service {
    public void print() {
        System.out.println("printing ServiceA.print()");
    } 
}

@Service(value="ServiceB")
public class ServiceB implements example.Service {
    public void print() {
        System.out.println("printing ServiceB.print()");
    } 
}

XML:

<beans>
    <alias name="${service.class}" alias="Service"/>
    <context:property-placeholder location="example/app.properties"/>
    <context:component-scan base-package="example"/>
<beans>

道具:

service.class=ServiceB

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