Spring MapFactoryBean example

The ‘MapFactoryBean‘ class provides developer a way to create a concrete Map collection class (HashMap and TreeMap) in Spring’s bean configuration file.

Here’s a MapFactoryBean example, it will instantiate a HashMap at runtime,, and inject it into a bean property.

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

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="maps">
			<bean class="org.springframework.beans.factory.config.MapFactoryBean">
				<property name="targetMapClass">
					<value>java.util.HashMap</value>
				</property>
				<property name="sourceMap">
					<map>
						<entry key="Key1" value="1" />
						<entry key="Key2" value="2" />
						<entry key="Key3" value="3" />
					</map>
				</property>
			</bean>
		</property>
	</bean>
 
</beans>

Alternatively, you also can use util schema and <util:map> 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="maps">
			<util:map map-class="java.util.HashMap">
				<entry key="Key1" value="1" />
				<entry key="Key2" value="2" />
				<entry key="Key3" value="3" />
			</util:map>
		</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:map" 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 [maps={Key2=2, Key1=1, Key3=3}] Type=[class java.util.HashMap]

You have instantiated a HashMap and injected it into Customer’s map property at runtime.

Download Source Code

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

Reference

  1. MapFactoryBean Javadoc
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About the Author

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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