Question

I was using spring to create objects through beans. Now I tried to use aop to create the same object and I get $Proxy cannot be cast to SaleRoom exception.

the previous xml was:

<?xml version="1.0" encoding="UTF-8"?>

<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:aop="http://www.springframework.org/schema/aop/spring-aop-2.5.xsd"
xmlns:context="http://www.springframework.org/schema/context/spring-context-2.5.xsd"
xmlns:flow="http://www.springframework.org/schema/webflow-config/spring-webflow-config- 1.0.xsd"
xmlns:jm s="http://www.springframework.org/schema/jms/spring-jms-2.5.xsd"
xmlns:jee="http://www.springframework.org/schema/jee/spring-jee-2.5.xsd"
xmlns:lang="http://www.springframework.org/schema/lang/spring-lang-2.5.xsd"
xmlns:osgi="http://www.springframework.org/schema/osgi/spring-osgi.xsd"
xmlns:tx="http://www.springframework.org/schema/tx/spring-tx-2.5.xsd"
xmlns:util="http://www.springframework.org/schema/util/spring-util-2.5.xsd"
xmlns:p="http://www.springframework.org/schema/p"

xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
http://www.springframework.org/schema/aop/spring-aop-2.5.xsd     http://www.springframework.org/schema/aop/spring-aop-2.5.xsd/spring-spring-aop-2.5.xsd-2.5.xsd
http://www.springframework.org/schema/context/spring-context-2.5.xsd     http://www.springframework.org/schema/context/spring-context-2.5.xsd/spring-spring-context-2.5.xsd-2.5.xsd
http://www.springframework.org/schema/webflow-config/spring-webflow-config-1.0.xsd     http://www.springframework.org/schema/webflow-config/spring-webflow-config-1.0.xsd/spring-spring-webflow-config-1.0.xsd-2.5.xsd
http://www.springframework.org/schema/jms/spring-jms-2.5.xsd     http://www.springframework.org/schema/jms/spring-jms-2.5.xsd/spring-spring-jms-2.5.xsd-2.5.xsd
http://www.springframework.org/schema/jee/spring-jee-2.5.xsd     http://www.springframework.org/schema/jee/spring-jee-2.5.xsd/spring-spring-jee-2.5.xsd-2.5.xsd
http://www.springframework.org/schema/lang/spring-lang-2.5.xsd     http://www.springframework.org/schema/lang/spring-lang-2.5.xsd/spring-spring-lang-2.5.xsd-2.5.xsd
http://www.springframework.org/schema/osgi/spring-osgi.xsd     http://www.springframework.org/schema/osgi/spring-osgi.xsd/spring-spring-osgi.xsd-2.5.xsd
http://www.springframework.org/schema/tx/spring-tx-2.5.xsd     http://www.springframework.org/schema/tx/spring-tx-2.5.xsd/spring-spring-tx-2.5.xsd-2.5.xsd
http://www.springframework.org/schema/util/spring-util-2.5.xsd     http://www.springframework.org/schema/util/spring-util-2.5.xsd/spring-spring-util-2.5.xsd-2.5.xsd
">
<bean id="sale01" class="application.common.entities.BidRoom">
<property name="itemId" value="0001"/>
<property name="lifeTime" value="15"/>
</bean>
</beans>

And I used the following code to create the sales:

    ApplicationContext context = new FileSystemXmlApplicationContext(SalesManager.getSalesSourceFile());
    SaleRoom saleRoom;
    List<String> salesNames = new LinkedList<String>();
    List<SaleRoom> allSales = new LinkedList<SaleRoom>();

    // Get all sales id's for beans
    NodeList salesNodeList = salesDoc.getElementsByTagName("bean");

    for (int i = 0; i < salesNodeList.getLength(); i++) {
        Node nNode = salesNodeList.item(i);
        salesNames.add(((Element) nNode).getAttribute("id").toString());
    }

    for (String saleName : salesNames) {
        if(saleName.contains("sale")) {
            saleRoom = (SaleRoom) context.getBean(saleName);
            allSales.add(saleRoom);
        }
    }

    return allSales;

This is the new xml:

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
           xmlns:aop="http://www.springframework.org/schema/aop"
           xsi:schemaLocation="
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.0.xsd
http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.0.xsd">

    <aop:aspectj-autoproxy>
        <aop:include name="logSettersCalls"/>
    </aop:aspectj-autoproxy>
    <bean id="logSettersCalls" class="application.logging.aop.LogSettersCalls"/>

    <bean id="sale01" class="application.common.entities.BidRoom">
        <constructor-arg index="0" type="int" value="0001"/>
        <constructor-arg index="1" type="int" value="15"/>
    </bean>
</beans>

The Aspect logging class:

@Aspect
public class LogSettersCalls {
   @Pointcut("execution(void set*(*))")
    public void setMethod() {}

    @Before("setMethod()")
    public void logSetterCall(JoinPoint theJoinPoint) {
        String methodName = theJoinPoint.getSignature().getName();
        Object newValue = theJoinPoint.getArgs()[0];
        Object theObject = theJoinPoint.getTarget();
        System.out.println("The method " + methodName + " is called on object " 
                + theObject + " with the value " + newValue);
    }
}

I’m using the same code for creating the beans via aop. and I get
Exception in thread “main” java.lang.ClassCastException: $Proxy11 cannot be cast to application.common.entities.SaleRoom

The line that throws the exception:
saleRoom = (SaleRoom) context.getBean(saleName);

Any help will be appreciated. Thanks.

Answer 1

Does your SaleRoom class implement some interface? If yes, then you should use interface and not class in you code:

ISaleRoom saleRoom = (ISaleRoom) context.getBean(saleName);

Because if your bean implements some interface then Spring by default will create proxy based on this interface.

Here is a good article about proxy creation in Spring.

Also you can change proxying mechanism for Spring AOP if you want to create proxy for target class. This is described here in reference documentation.