Spring boot auto configuration fails to bind property file from jar to a bean

Question

what I'd like to do is to have jar file with configured messaging queue. The structure of my project is the following: I have spring boot application in the module emulator which uses mq-api module (in terms of Maven)

emulator

package emulator;

@ComponentScan(basePackageClasses = {MqConfig.class})
@SpringBootApplication
public class Application {
    static final Logger log = LoggerFactory.getLogger(Application.class);


    public static void main(String[] args) throws InterruptedException {
        SpringApplication.run(Application.class, args);
    }


}

mq-api

package mq;

@Configuration
@EnableRabbit
@ImportResource(value = "classpath:/mq.properties", reader = PropertiesBeanDefinitionReader.class)
public class MqConfig {
    @Bean
    public TopicExchange topicExchange() {
        return new TopicExchange("exc");
    }
}

mq.properties inside the mq-api.jar

spring.rabbitmq.host=localhost

Running the emulator application I have the exception:

14:38:22.447 ERROR o.s.boot.SpringApplication - Application startup failed
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'spring.rabbitmq': Instantiation of bean failed; nested exception is java.lang.IllegalStateException: No bean class specified on bean definition
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:1105) ~[spring-beans-4.2.3.RELEASE.jar:4.2.3.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1050) ~[spring-beans-4.2.3.RELEASE.jar:4.2.3.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:510) ~[spring-beans-4.2.3.RELEASE.jar:4.2.3.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:482) ~[spring-beans-4.2.3.RELEASE.jar:4.2.3.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306) ~[spring-beans-4.2.3.RELEASE.jar:4.2.3.RELEASE]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230) ~[spring-beans-4.2.3.RELEASE.jar:4.2.3.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302) ~[spring-beans-4.2.3.RELEASE.jar:4.2.3.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197) ~[spring-beans-4.2.3.RELEASE.jar:4.2.3.RELEASE]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:772) ~[spring-beans-4.2.3.RELEASE.jar:4.2.3.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:838) ~[spring-context-4.2.3.RELEASE.jar:4.2.3.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:537) ~[spring-context-4.2.3.RELEASE.jar:4.2.3.RELEASE]
    at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh(EmbeddedWebApplicationContext.java:118) ~[spring-boot-1.3.0.RELEASE.jar:1.3.0.RELEASE]
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:752) [spring-boot-1.3.0.RELEASE.jar:1.3.0.RELEASE]
    at org.springframework.boot.SpringApplication.doRun(SpringApplication.java:347) [spring-boot-1.3.0.RELEASE.jar:1.3.0.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:295) [spring-boot-1.3.0.RELEASE.jar:1.3.0.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1112) [spring-boot-1.3.0.RELEASE.jar:1.3.0.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1101) [spring-boot-1.3.0.RELEASE.jar:1.3.0.RELEASE]
    at net.tipstery.emulator.Application.main(Application.java:24) [classes/:na]
Caused by: java.lang.IllegalStateException: No bean class specified on bean definition
    at org.springframework.beans.factory.support.AbstractBeanDefinition.getBeanClass(AbstractBeanDefinition.java:356) ~[spring-beans-4.2.3.RELEASE.jar:4.2.3.RELEASE]
    at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:66) ~[spring-beans-4.2.3.RELEASE.jar:4.2.3.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:1098) ~[spring-beans-4.2.3.RELEASE.jar:4.2.3.RELEASE]
    ... 17 common frames omitted

If I remove @ImportResource application starts without error and of course skips configuration file mq.properties

I use spring boot 1.3.0 (boot-starter, *-starter-amqp)

Answer 1

As @M. Deinum points out, @ImportResource is meant for importing bean definitions from XML files. It won't work for loading property files. In order to load property files, you can use @PropertySource . Take a look at this post on a good example of how to do this.