Spring SetFactoryBean example

The ‘SetFactoryBean‘ class provides developer a way to create a concrete Set collection (HashSet and TreeSet) in Spring’s bean configuration file.

Here’s a ListFactoryBean example, it will instantiate an HashSet at runtime, and inject it into a bean property

package com.mkyong.common;
 
import java.util.Set;
 
public class Customer 
{
	private Set sets;
	//...
}

Spring’s bean configuration file.

<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://www.springframework.org/schema/beans
	http://www.springframework.org/schema/beans/spring-beans-2.5.xsd">
 
	<bean id="CustomerBean" class="com.mkyong.common.Customer">
		<property name="sets">
			<bean class="org.springframework.beans.factory.config.SetFactoryBean">
				<property name="targetSetClass">
					<value>java.util.HashSet</value>
				</property>
				<property name="sourceSet">
					<list>
						<value>1</value>
						<value>2</value>
						<value>3</value>
					</list>
				</property>
			</bean>
		</property>
	</bean>
 
</beans>

Alternatively, you also can use util schema and <util:set> to achieve the same thing.

<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
	xmlns:util="http://www.springframework.org/schema/util"
	xsi:schemaLocation="http://www.springframework.org/schema/beans
	http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
	http://www.springframework.org/schema/util
	http://www.springframework.org/schema/util/spring-util-2.5.xsd">
 
	<bean id="CustomerBean" class="com.mkyong.common.Customer">
		<property name="sets">
			<util:set set-class="java.util.HashSet">
				<value>1</value>
				<value>2</value>
				<value>3</value>
			</util:set>
		</property>
	</bean>
 
</beans>

Remember to include the util schema, else you will hit the following error

Caused by: org.xml.sax.SAXParseException: 
	The prefix "util" for element "util:set" is not bound.

Run it…

package com.mkyong.common;
 
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
 
public class App 
{
    public static void main( String[] args )
    {
    	ApplicationContext context = new ClassPathXmlApplicationContext("SpringBeans.xml");
 
    	Customer cust = (Customer)context.getBean("CustomerBean");
    	System.out.println(cust);
 
    }
}

Ouput

Customer [sets=[3, 2, 1]] Type=[class java.util.HashSet]

You have instantiated HashSet and and injected it into Customer’s sets property at runtime.

Download Source Code

Download It – Spring-SetFactoryBean-Example.zip (5KB)

Reference

  1. SetFactoryBean Javadoc
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mkyong
Founder of Mkyong.com and HostingCompass.com, love Java and open source stuff. Follow him on Twitter, or befriend him on Facebook or Google Plus. If you like my tutorials, consider make a donation to these charities.

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