Getting instance of a ProxyFactoryBean

[arnel]

Hello there!

New to Spring.

How do we get instance of a ProxyFactoryBean in java.
The usual way is context.getBean("BeanId").

What if i have a constructor? How do we get the instance. This can be achieve via constructor injection in my config file but i get java.lang.ClassCastException when i call the ProxyFactoryBean in my code.

arnel


[/code]

[Rod Johnson]

You want the instance of the factory bean, not the object it creates? You can do this as follows:

context.getBean("&BeanId").

Note the use of the ampersand before the name.[/quote]

[arnel]

No sir. I need an object but my object has a constructor that takes a parameter of certain type. I have a doubt that the proxy bean factory does not create an object that has a constructor. What i need to be proxied is an object that takes parameter of a certain type.

Take a look at my bean config:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN"
	"http&#58;//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">
		<constructor-arg index="0">
 				<ref bean="SpringCustomer"/>
		</constructor-arg>
		
		<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>

This is my java code:

........

import org.springframework.context.*;
import org.springframework.context.support.FileSystemXmlApplicationContext;
import org.springframework.aop.framework.ProxyFactoryBean;

public class SpringBreakMain {

	public static void main(String [] args) {
		ApplicationContext context = new FileSystemXmlApplicationContext("D:\\SpringBreak\\src\\SpringBreak.xml");
		(Bank) bank =(Bank)context.getBean("Bank");
		bank.withdrawMoney(2500);
		
	}
}

[/code]
Now if i run the code it spits-out this error:

....................... 1 constructor arguments specified but no matching constructor found in bean 'Bank' (hint: specify index arguments for simple parameters to avoid type ambiguities.

[robh]

Try removing the constructor-arg definition from the ProxyFactoryBean and setting proxyTargetClass to false.

Rob

[arnel]

Try removing the constructor-arg definition from the ProxyFactoryBean and setting proxyTargetClass to false.

...now i got this error:

.......initialization of bean failed; nested exception is org.aopalliance.aop.AspectException: null

I am new to Spring so i really don't have any idea about this error. My assumption is that the ProxyFactoryBean did not create my object with constructor that takes a parameter, thats why when i try to invoke in my code using context.getBean("BeanId") i am geting a null object. I think one solution for this is by method-injection instead of constructor-injection bcause the ProxyFactoryBean does not allow me to do this. Correct me if i am wrong.

Thanks

[robh]

With proxyTargetClass set to false, you only create the object once in its definition so you DO need the <constructor-arg> definitions there. In the ProxyFactoryBean you don't need the <constructor-arg> definition because the proxy is created from your defined interface.

Can you post the full stack trace for this error?

Rob

[arnel]

Hi rob !

I got it working already . All my advice methods are being fired as i expected. Thank you for your support. More power to the Spring Team.