Spring使用注释从一个类创建两个bean

Question

我可以使用以下代码使用xml配置从一个java类中的两个bean创建:

    <context:component-scan base-package="some.package"/>

    <bean id="dependentBean" class="some.package.DependentBean">
        <property name="firstBean" ref="firstBean"/>
    </bean>

    <bean id="firstBean" class="some.package.Handler">
        <constructor-arg index="0" ref="service"></constructor-arg>
        <property name="defaultUrl" value="url/first"></property>
    </bean>

    <bean id="secondBean" class="some.package.Handler">
        <constructor-arg index="0" ref="service"></constructor-arg>
        <property name="defaultUrl" value="url/second"></property>
    </bean> 

我的目标是将firstBean和secondBean移动到基于java的配置,如下所示:

package some.package;

@Configuration
public class Configuration {

    @Bean(name="firstBean")
    public Handler firstHandler(Service service){
        Handler handler= new Handler(service);
        handler.setDefaultTargetUrl("url/first");
        return handler;
    }


    @Bean(name="secondBean")
    public Handler secondHandler(Service service){
        Handler handler = new Handler(service);
        handler.setDefaultTargetUrl("url/second");
        return handler;
    }
}

但是当上下文开始加载时,spring会抛出以下异常:

Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No bean named 'firstBean' is defined

然而,它适用于这种情况:

package some.package;

    @Component
    public class Filter{

        private Handler handler;

        @Autowired
        public Filter(@Qualifier("secondBean") Handler handler) {
             this.handler = handler;
        }

    }

处理程序实现:

public class Handler {

    private Service service;

    @Autowired
    public Handler(Service service) {
        this.service = service;
    }

}

Answer 1

@Autowired始终按类型。但是您的配置中有两个处理程序。因此，当您尝试自动装配处理程序类时，您必须指定限定符。通过这个 spring 可以确定要注入哪个实例。否则，spring 会抛出错误并显示NoSuchBeanDefinitionFoundError。预计一发现二。

希望有帮助。