Autowiring of fields failed; nested exception is org.springframework.beans.factory.BeanCreationExcep

[peter tong]

it is a standalone application to test Ioc feature of spring, but I always got the following exception:
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'customerService': Autowiring of fields failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private com.cybelink.ioc.DataSource com.cybelink.ioc.CustomerService.dataSource; nested exception is java.lang.NoClassDefFoundError: org/apache/velocity/exception/VelocityException

the application has 3 class as follow (the customer class is not related and so not paste the source here):

package com.cybelink.ioc;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import org.springframework.stereotype.Component;
import org.springframework.stereotype.Controller;

/**
 *
 * This class uses the DataSource to load Customer data 
 */

@Controller
public class CustomerService {
	@Autowired
	private DataSource dataSource;
	private Customer customer;
	
	public static void main(String[] args){
		CustomerService customerService = new CustomerService();
		customerService.method1();		
	}
	
	public void method1(){
		ClassPathXmlApplicationContext ctx = new ClassPathXmlApplicationContext("applicationContext.xml");
		if (dataSource == null)
			System.out.println("dataSource == null");
		customer=(Customer)dataSource.retrieveObject();
		//System.out.println(getCustomerName());
	}	
	
	public CustomerService() {
		super();		
	}
}

Interface DataSource

package com.cybelink.ioc;

/**
 *
 * Interface that must be implemented by all types of DataSource
 */
public interface DataSource {
	public Object retrieveObject();
	public void setDataSourceName(String name);
	public String getDataSourceName();
	public void storeObject(Object object);
}

Implementation class of interface DataSource

package com.cybelink.ioc;

import org.springframework.stereotype.Component;
import org.springframework.stereotype.Repository;

/**
 *
 * This class will be used to load the Customer from a Relational Database.
 */

@Repository
public class RelationalDataSource implements DataSource {
	private String name;
	
	/**
	 * Default constructor
	 */
	public RelationalDataSource() {
		super();
	}

	/**
	 * Using the DataSource retrieve data for Customer and build a 
	 * Customer object to return it to the caller
	 */
	public Object retrieveObject() {
		//get data for Customer object from DB and create a 
		//Customer object
		return new Customer("Relational",10);
	}

	/**
	 * Set the DataSource name
	 */
	public void setDataSourceName(String name) {
		this.name=name;		
	}

	/**
	 * Return the name of the DataSource
	 */
	public String getDataSourceName() {
		return name;
	}

	/**
	 * Store Customer into relatioanl DB
	 */
	public void storeObject(Object object) {
		//store the customer data into Relatioanl DB
		
	}

}

the applicationContext.xml is as follow

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

<!--
  - Application context definition for JPetStore's business layer.
  - Contains bean references to the transaction manager and to the DAOs in
  - dataAccessContext-local/jta.xml (see web.xml's "contextConfigLocation").
  -->
<beans xmlns="http://www.springframework.org/schema/beans"
		xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
		xmlns:context="http://www.springframework.org/schema/context"
		xmlns:aop="http://www.springframework.org/schema/aop"
		xmlns:tx="http://www.springframework.org/schema/tx"
		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 http://www.springframework.org/schema/aop/spring-aop-2.5.xsd
			http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-2.5.xsd
			http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-2.5.xsd">

	<!-- To allow autodetect and register of beans under com.cybelink.ioc package -->
	<context:component-scan base-package="com.cybelink.ioc" />
	
	
 
	<!-- Velocity Engine for email template -->
	<bean id="velocityEngine" class="org.springframework.ui.velocity.VelocityEngineFactoryBean">
      <property name="velocityProperties">
         <value>
         		input.encoding=UTF-8
            resource.loader=class
            class.resource.loader.class=org.apache.velocity.runtime.resource.loader.ClasspathResourceLoader
         </value>
      </property>
   </bean>    
</beans>

[peter tong]

after change the CustomerService class as follow, the program can run

@Component
public class CustomerService {
	@Autowired	
	private DataSource dataSource;
	private Customer customer;
	
	public static void main(String[] args){
		ApplicationContext ctx = new ClassPathXmlApplicationContext("applicationContext.xml");
		// don't create the customerService using new, should use spring method to make
		// customerService a spring managed bean!!
		//CustomerService customerService = new CustomerService();
		
		CustomerService customerService = (CustomerService)ctx.getBean("customerService");
		customerService.method1();		
	}
	
	public void method1(){		
		if (dataSource == null)
			System.out.println("dataSource == null");
		customer=(Customer)dataSource.retrieveObject();
		System.out.println(getCustomerName());
	}
	...
// other non-related code
}

But now if I change the constructor of class RelationalDataSource to non-default, like the following:

public RelationalDataSource(int a) {  // remove the empty args constructor
     super();  
}  

then the following error prompted

Exception in thread "main" org.springframework.beans.factory.BeanCreationException: 
Error creating bean with name 'customerService': Autowiring of fields failed; 
nested exception is org.springframework.beans.factory.BeanCreationException: 
Could not autowire field: private com.cybelink.ioc.DataSource com.cybelink.ioc.CustomerService.dataSource; 
nested exception is org.springframework.beans.factory.BeanCreationException: 
Error creating bean with name 'relationalDataSource' defined in file [C:\workspace\workspace1\Test\bin\com\cybelink\ioc\RelationalDataSource.class]: 
Instantiation of bean failed; nested exception is org.springframework.beans.BeanInstantiationException: 
Could not instantiate bean class [com.cybelink.ioc.RelationalDataSource]: 
No default constructor found; nested exception is java.lang.NoSuchMethodException: 
com.cybelink.ioc.RelationalDataSource.<init>()

so if the bean has no default constructor, then how to pass constructor args using autowire annotation?