Spring 3 AOP java.lang.ClassCastException: $Proxy43 cannot be cast

Question

I use Spring 3.1 and APO(proxy).

Annotation which was provided used as Pointcat. In this case Spring AOP proxy method "getMergeMappingsAndCals" was annotated with CalendarMappingAnnotation

My advise is AfterReturning

Aspect:

@Component
@Aspect
public class MappingFilterAspect{
    /**
     *
     * @param retVal
     */
    @AfterReturning(
        pointcut="@annotation(...annotation.CalendarMappingAnnotation)",
        returning="retVal"
    )
    public void calendarMappingFilter(Object retVal) {


    }
}

Annotation:

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
public @interface CalendarMappingAnnotation {
}

Usage:

@Component
public class ApoiMappingManagerImpl implements ApoiMappingManager, ApplicationContextAware, Serializable {
    ...
    @CalendarMappingAnnotation
    public MergedMapAndCalsBeanCollection getMergeMappingsAndCals(){
        ...
    }
}

Configuration:

<context:component-scan base-package="...aus.aspect" />
<aop:aspectj-autoproxy/>

Stacktrace:

java.lang.ClassCastException: $Proxy43 cannot be cast to ...mapping.cals.ApoiMappingManagerImpl
[JVM ...]   at ...helpers.SaveFillRestCalsClientHelper.init(SaveFillRestCalsClientHelper.java:62)
[JVM ...]   at ...DispatcherImpl.loadPlugin(DispatcherImpl.java:426)
[JVM ...]   at ...dispatcher.DispatcherImpl.run(DispatcherImpl.java:181)
[JVM ...]   at ...DispatcherImpl.complete(DispatcherImpl.java:319)
[JVM ...]   at ...DispatcherImpl.process(DispatcherImpl.java:259)
[JVM ...]   at ...RunnerImpl.run(RunnerImpl.java:88)
[JVM ...]   at ...JvmLauncherSlave.main(JvmLauncherSlave.java:40)

Biju Kunjummen · Accepted Answer · 2013-05-09 14:37:19Z

2

The behavior looks correct.

It looks like you are casting an instance of a bean of type ApoiMappingManagerImpl and the code is throwing a runtime exception. The reason this is an expected behavior is because underlying you are using Spring AOP and Spring AOP essentially creates a dynamic proxy for you, this proxy essentially implements the interface ApoiMappingManager, internally composes the ApoiMappingManagerImpl and delegates calls to this composed class. So the proxy implements ApoiMappingManager and does NOT extend ApoiMappingManagerImpl and hence the error.

To fix it you should be if required casting to the interface not the implementation.

answered May 9, 2013 at 14:37

Biju Kunjummen

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Veniamin · Accepted Answer · 2013-05-09 14:39:10Z

0

Answer

This kind of issue happened because I don`t describe this method in interface which was implemented by ApoiMappingManagerImpl

public interface ApoiMappingManager {
    public MapBeanCollection assembleMaps();
    public String getRootFolder();
    public void setRootFolder(String rootFolder);
    public ErrorList getErrorList();
    public Set<String> getAgentList();
    public Set<MapBean> getMappingSetByAgentName(String agentName);
    public CalBeanCollection assembleCals(String dateStr);
    public CalBeanCollection getCalBeanCollection();
    public MergedMapAndCalsBeanCollection getMergeMappingsAndCals();  // was missed
}

answered May 9, 2013 at 14:39

Veniamin

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