Class cast exception

[arnel nicolas]

Hello there

i am having problem during the invocation of my proxy bean. It says ....java.lang.ClassCastException.

  
........
import org.springframework.context.*;
import org.springframework.context.support.FileSystemXmlApplicationContext;
 
public class SpringBreakMain {
 
public static void main(String [] args) {
ApplicationContext context = new FileSystemXmlApplicationContext("D:\\AppConfig\\SpringBreak.xml");
Bank bank=(Bank)context.getBean("Bank"); //Error here....
bank.withdrawMoney(customer, 2500);

}
}

some of my bean config

....
<bean id="Bank" class="org.springframework.aop.framework.ProxyFactoryBean">
<property name="proxyInterfaces">
<value>arnel.nicolas.IBank</value>
</property>
<property name="target">
<ref bean="BankTarget"/>
</property>
 
<property name="interceptorNames">
<list>
<value>BankPointCutAdvisor</value>
</list>
</property>
 

</bean>
 

any help is highly appreciated. Thanks in advance.

arnel

[Lasse Koskela]

Should that one line say IBank instead of Bank?

[arnel nicolas]

Hi Lasse,

Thanks for your attention. The IBank there is an interface. AFAIK to create a proxy bean in Spring requires an interface instead of the direct class implementation. The target property of this proxy bean requires the IBank implementation....if i am correct.

during the invocation of this code:

  
Bank bank=(Bank)context.getBean("Bank");

it spit-out an error saying java.lang.ClassCastException

When i change my code to like this:

Bank bank=(Bank)context.getBean("Bank", Bank.class);

the error change to: Bean name "Bank" must be of type [arnel.nicolas.Bank],
but was actually of type [$Proxy0].

I have a doubt if Spring created a bean name "Bank" of arnel.nicolas.Bank type.

Anyway thanks for your reply. I will just check their forum.

[arnel nicolas]

ok guys, i just refactored my code. It seems that there is a problem during the creation of my ProxyFactoryBean Bank. My target class TargetBank has a constructor. So values can be set thru constructor-injection via my bean config file. I removed the constructor and provide a method for it and set the values via method-injection. The code works find and it fires all my advice methods as i expected.

Now, is there a way to get the instance of a ProxyFactoryBean with constructor in the source code? like

 Bank bank = (Bank)context.getBean("BeanId",<constructor parameter> :wink: ;

Funny huh!?

[Ryan Breidenbach]

From your original code example, try this instead:

IBank bank = (IBank) context.getBean("Bank");

Spring's bean factory will not return an instance of a Bank, but rather a dynamically created object that implements the IBank interface that proxies method invocations to your a Bank object.

[arnel nicolas]

Originally posted by Ryan Breidenbach:
From your original code example, try this instead:

IBank bank = (IBank) context.getBean("Bank");

Spring's bean factory will not return an instance of a Bank, but rather a dynamically created object that implements the IBank interface that proxies method invocations to your a Bank object.

Hmm...but my concrete class Bank has a constructor that takes Object of Customer type as a parameter . I am assuming that Spring's bean factory will do create a proxy object with parameter as i have in my Target class (referring to Bank). I tried to change the code basing from your suggestion but the compiler is complaining about

java.lang.ClassCastException

error. I have a doubt that the bean factory did not create a proxy bean that takes a constructor of customer type thats why i am having that error.

Here is my bean config:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN"
"http://www.springframework.org/dtd/spring-beans.dtd">
 
<beans>
<bean id="SpringCustomer" class="arnel.nicolas.Customer">
<property name="firstname">
<value>Arnel</value>
</property>
<property name="lastname">
<value>Nicolas</value>
</property>
</bean>
 
<bean id="BankTarget" class="arnel.nicolas.Bank">
<constructor-arg index="0">
 <ref bean="SpringCustomer"/>
</constructor-arg>
 
</bean>
 
<bean id="WithDrawalAdvice" class="arnel.nicolas.BeforeWithdrawal"/>
 
<bean id="BankPointCutAdvisor" class="org.springframework.aop.support.NameMatchMethodPointcutAdvisor">
<property name="advice">
<ref bean="WithDrawalAdvice"/>
</property>
<property name="mappedName">
<value>withdrawMoney</value>
</property>
</bean>
 
<bean id="Bank" class="org.springframework.aop.framework.ProxyFactoryBean">
 

<property name="proxyInterfaces">
<value>arnel.nicolas.IBank</value>
</property>
 
<property name="proxyTargetClass">
<value>true</value>
</property>
 
<property name="target">
<ref bean="BankTarget"/>
</property>
 
<property name="interceptorNames">
<list>
<value>BankPointCutAdvisor</value>
</list>
</property>
 
</bean>
 

</beans>

[arnel nicolas]

Originally posted by Ryan Breidenbach:
From your original code example, try this instead:

IBank bank = (IBank) context.getBean("Bank");

Spring's bean factory will not return an instance of a Bank, but rather a dynamically created object that implements the IBank interface that proxies method invocations to your a Bank object.

Hello there Mr. Breidenbach,

Discard my previous posting, you were right . I took your suggestion.The bug there is not during my invocation but it is now in my Advice method. I got it working already.

Just a comment, Spring AOP is nice and pretty straight forward but sometimes they are hard to debug

Thanks a lot!

arnel

[sebastian ismael]

hi arnel, i�m from argentina, sorry for my english !!!

i have the same problem!!! please help me:

ApplicationContext context = new FileSystemXmlApplicationContext("C:\\eclipse3.0\\workspace\\SpringTest\\war\\WEB-INF\\SpringTest-servlet.xml");
Product product = (Product)context.getBean("product") ;

my xml is:

<!-- Bean configuration -->
<bean id="product" class="org.springframework.aop.framework.ProxyFactoryBean">
<property name="proxyInterfaces">
<value>com.test.security.SecurityAdvices</value>
</property>
<property name="target">
<ref local="productTarget"/>
</property>
<property name="interceptorNames">
<list>
<value>securityAdvisor</value>
</list>
</property>
</bean>

<!-- Bean Classes -->
<bean id="productTarget" class="com.test.business.beans.Product">
</bean>

<!-- Advisor pointcut definition for after advice -->
<bean id="securityAdvisor" class="org.springframework.aop.support.RegexpMethodPointcutAdvisor">
<property name="advice">
<ref local="securityAdvice"/>
</property>
<property name="pattern">
<value>.*</value>
</property>
</bean>

<!-- Advice classes -->
<bean id="securityAdvice" class="com.test.aop.BeforeCreateBusinessObjectBeanAdvice"/>

regars !!!

seba