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.
<?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="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.
<?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="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.
