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 aHashMapand injected it intoCustomer’smap` property at runtime.