Question

I have two Service classes which implement the same interface

ServiceClass1

@Service
public class ServiceClass1 implements ItemsService{

@Autowired
Class1DaoImpl class1Dao;

@Transactional
public List<Class1> getAllItems() {
    return class1Dao.getAllItems();

}

ServiceClass2

@Service
public class ServiceClass2 implements ItemsService{

@Autowired
Class2DaoImpl class2Dao;

@Transactional
public List<Class2> getAllItems() {
    return class2Dao.getAllItems();

}

And this is the controller class

     @Controller
     public class IndexController {


    @Autowired
    ServiceClass1 serviceClass1;

    @Autowired
    ServiceClass1 serviceClass2;    

        ............
        .....
}

I got this error when the page was requested

java.lang.IllegalArgumentException: Can not set com.package.ServiceClass1 field com.package.IndexController.serviceClass1 to $Proxy25
sun.reflect.UnsafeFieldAccessorImpl.throwSetIllegalArgumentException(UnsafeFieldAccessorImpl.java:146)
sun.reflect.UnsafeFieldAccessorImpl.throwSetIllegalArgumentException(UnsafeFieldAccessorImpl.java:150)
sun.reflect.UnsafeObjectFieldAccessorImpl.set(UnsafeObjectFieldAccessorImpl.java:63)
java.lang.reflect.Field.set(Field.java:657)
org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:500)
org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:84)
org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:284)
org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1074)
org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:517)
org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:456)
org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:295)
org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:225)
org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:292)
org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:194)
org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:580)
org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:913)
org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:464)
org.springframework.web.servlet.FrameworkServlet.configureAndRefreshWebApplicationContext(FrameworkServlet.java:609)
org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:571)
org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:623)
org.springframework.web.servlet.FrameworkServlet.initWebApplicationContext(FrameworkServlet.java:491)
org.springframework.web.servlet.FrameworkServlet.initServletBean(FrameworkServlet.java:432)
org.springframework.web.servlet.HttpServletBean.init(HttpServletBean.java:133)
javax.servlet.GenericServlet.init(GenericServlet.java:212)
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:859)
org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
java.lang.Thread.run(Thread.java:662)

I did some google-ing and can’t seem to find any solid answer to why am I getting this error?

Answer 1

You need to autowire against the interface type, not the class type, i.e.

@Autowired
ItemsService serviceClass1;

If you have multiple beans that implement ItemsService, then autowiring isn’t really appropriate. Consider using @Resource instead:

@Resource(name="serviceClass1")
ItemsService serviceClass1;

@Resource(name="serviceClass2")
ItemsService serviceClass1;