Spring Data JPA - dependency injection of concrete entity class - spring

Question

We are migrating from MyBatis over to Spring Data JPA (using hibernate). Originally, the Spring configuration specified a util:map of specific domain level objects as values that were referenced by an enum key. Thus the map was injected in to a service level class. This map was then used to get the domain level object based on a specific enum during the process flow. Now we have refactored the service layer to use Spring Data enabled #Entity domain level objects, when we try and get an instance of the entity using the enum key, it returns a proxy (as you would expect). As such, when we try and make use of the returned instance we get a ClassCastException (Caused by: java.lang.ClassCastException: com.sun.proxy.$Proxy43 cannot be cast to com.ourpackage.Event). My question is: How can I inject an #Entity class in to a util:map configuration so further properties can be set?
Here is the configuration of the map of entity objects and enum lookup keys:
<?xml version="1.0" encoding="UTF-8"?>
<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-3.1.xsd
http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-3.1.xsd">
<!--*********************************************************************-->
<!-- Event bean definitions -->
<!--*********************************************************************-->
<bean id="workEvent" class="com.ourpackage.Event">
<constructor-arg name="action" type="java.lang.String" value="action"/>
<constructor-arg name="type" type="java.lang.String" value="type"/>
<constructor-arg name="description" type="java.lang.String" value="A description"/>
</bean>
<!--*********************************************************************-->
<!-- Event Maps -->
<!--*********************************************************************-->
<util:map id="workEvents" map-class="java.util.HashMap" key-type="com.anotherpackage.EventType" value-type="com.ourpackage.Event">
<entry>
<key><value type="com.anotherpackage.EventType">WORK_ITEM</value></key>
<ref local="workEvent"/>
</entry>
</util:map>
</beans>
And here is the entity domain class definition:
package com.ourpackage;
import static javax.persistence.GenerationType.IDENTITY;
import static javax.persistence.TemporalType.TIMESTAMP;
import java.util.Date;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.Table;
import javax.persistence.Temporal;
import org.apache.commons.lang.builder.ToStringBuilder;
import org.apache.commons.lang.builder.ToStringStyle;
import org.springframework.transaction.annotation.Transactional;
import com.basepackage.ServiceEntity;
/**
* The Class Event.
*
*/
#Entity
#Table(name = "events")
#Transactional(readOnly = true)
public class Event extends ServiceEntity {
....
}
Here is the code from the service class making use of this map:
// The following line produces the ClassCastException
workEvent = workEvents.get(EventType.WORK_ITEM);
This can of course be resolved by scrapping the dependency injection configuration and simply constructing the Event class on the fly, however configuration is the preferred approach.
Any help would be greatly appreciated.

Answer 1

The problem is the concrete class is no longer com.ourpackage.Event, because Spring wrapped in it an proxy of type com.sun.proxy.$Proxy43, and it's not possible to cast a proxy to an Event because they are two completely different types.
To solve this, make event implement an interface and cast to that interface instead of casting to a concrete class.
In general it is a generally good practice to avoid casting to concrete types in applications that heavily use proxying/AOP (like Spring/Hibernate applications).