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Posted to dev@aries.apache.org by "Ancoron Luciferis (JIRA)" <ji...@apache.org> on 2015/01/21 18:29:34 UTC
[jira] [Commented] (ARIES-1288) ClassCastException with proxy set
in bean of generic class
[ https://issues.apache.org/jira/browse/ARIES-1288?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14285928#comment-14285928 ]
Ancoron Luciferis commented on ARIES-1288:
------------------------------------------
The key seems to be the type detection for the setter method being invoked for the "secureMeterDaoBean" bean.
The {{ReflectionUtils}} use the very simple {{setterMethod.getGenericParameterTypes()[0]}} to determine the setter parameter type, which in this case only results in {{CrudDao}} as the setter method itself is declared in the generic {{SecureDao}} class, missing out the static type information provided only by the concrete implementation like the {{SecureMeterDao}} class in this example.
> ClassCastException with proxy set in bean of generic class
> ----------------------------------------------------------
>
> Key: ARIES-1288
> URL: https://issues.apache.org/jira/browse/ARIES-1288
> Project: Aries
> Issue Type: Bug
> Components: Blueprint
> Affects Versions: blueprint-core-1.4.2
> Reporter: Ancoron Luciferis
>
> I have a blueprint configuration as follows (actually from a third-party application):
> {code:xml}
> <?xml version="1.0" encoding="UTF-8"?>
> <blueprint xmlns="http://www.osgi.org/xmlns/blueprint/v1.0.0"
> xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
> xmlns:jpa="http://aries.apache.org/xmlns/jpa/v1.0.0"
> xmlns:tx="http://aries.apache.org/xmlns/transactions/v1.0.0"
> xsi:schemaLocation="
> http://www.osgi.org/xmlns/blueprint/v1.0.0 http://www.osgi.org/xmlns/blueprint/v1.0.0/blueprint.xsd
> http://aries.apache.org/xmlns/jpa/v1.0.0 http://aries.apache.org/xmlns/jpa/v1.0.0
> http://aries.apache.org/xmlns/transactions/v1.0.0 http://aries.apache.org/xmlns/transactions/v1.0.0">
> <bean id="meterDaoBean" class="com.third.party.impl.dao.jpa.JpaMeterDao">
> <jpa:context unitname="MeterUnit" property="entityManager" />
> </bean>
> <reference id="securityService" interface="com.third.party.api.SecurityService" availability="optional"/>
> <bean id="secureMeterDaoBean" class="com.third.party.impl.dao.secure.SecureMeterDao">
> <property name="dao" ref="meterDaoBean" />
> <property name="securityService" ref="securityService" />
> </bean>
> <bean id="meterBean" class="com.third.party.impl.MeterServiceImpl">
> <tx:transaction method="*" value="Required" />
> <property name="meterDao" ref="secureMeterDaoBean" />
> </bean>
> <service ref="meterBean" interface="com.third.party.api.MeterService"/>
> </blueprint>
> {code}
> ...and the (for this issue relevant) class definitions look as follows:
> {code}
> public interface CrudDao<T> {
> }
> public abstract class SecureDao<T, R extends CrudDao<T>> implements CrudDao<T> {
> protected R dao;
> // ...
> public void setDao(R dao) {
> this.dao = dao;
> }
> }
> public interface MeterDao extends CrudDao<MeterEntity> {
> }
> public class JpaMeterDao extends JpaCrudDao<MeterEntity> implements MeterDao {
> }
> public class SecureMeterDao extends SecureDao<MeterEntity, MeterDao> implements MeterDao {
> // ...
> public MeterEntity get(String id) {
> // some security stuff...
> dao.get(id);
> }
> }
> {code}
> \\
> ...now with that usage of generics the proxy that gets created for the "dao" member in the {{SecureMeterDao}} bean instance only implements {{CrudDao}}, but not {{MeterDao}}.
> So, although the initial blueprint setup of beans and services is fine, any call traveling through the {{SecureMeterDao}} results in a {{ClassCastException}}:
> {noformat}
> java.lang.ClassCastException: Proxyf427f861_7a7d_41e8_98c7_a09aea99f756 cannot be cast to com.third.party.impl.dao.MeterDao
> at com.third.party.impl.dao.secure.SecureMeterDao.get(SecureMeterDao.java:47)
> at com.third.party.impl.MeterServiceImpl.get(MeterServiceImpl.java:96)
> at Proxy8bef53d7_0df3_4724_a67c_fb296af2aee2.get(Unknown Source)
> at Proxya8f9ae87_fa39_42ae_bf11_baa82efa76cc.get(Unknown Source)
> ...
> {noformat}
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