The ‘SetFactoryBean‘ class provides developer a way to create a concrete Set collection (HashSet and TreeSet) in Spring’s bean configuration file.
package com.mkyong.common;
import java.util.Set;
public class Customer {
private Set sets;
//...
}
Spring’s bean configuration file.
<?xml version="1.0"?>
<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.
<?xml version="1.0"?>
<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.
