hhhmm, you asked for some "Spring wizardry!", here you are:
I think this is an excellent case for some AOP magics. I will define an interceptor for all the DAO (or services if you like) calls. My interceptor will intercept :wink: Spring unchecked exceptions (all Spring thrown exceptions are unchecked), extract the cause exception and convert it to a User Defined Exception.
1. my interceptor
import org.aopalliance.intercept.MethodInterceptor;
import org.aopalliance.intercept.MethodInvocation;
import org.springframework.core.NestedRuntimeException;
public class Interceptor implements MethodInterceptor {
public Object invoke(MethodInvocation invocation) throws Throwable {
try {
//invoke the underlying method
Object result = invocation.proceed();
return result;
} catch (NestedRuntimeException e) {
//extract the cause exception
NestedRuntimeException cause = e.getCause();
//convert the exception into User defined exception then rethrow it
throw new Exception ("error returned", e.getCause());
}
}
}
2. configure my interceptor in applicationContext.xml
<bean id="myInterceptor" class="Interceptor" />
3. configure a transaction template, I will omit the configuration for transactionManager and sessionFactory:
<!-- transaction template -->
<bean id="txProxyTemplate" class="org.springframework.transaction.interceptor.Transa ctionProxyFactoryBean" lazy-init="true">
<property name="transactionManager"><ref local="transactionManager"/></property>
<property name"preInterceptors">
<list>
<ref local="myInterceptor"/>
</list>
</property>
<property name="transactionAttributes">
<props>
<prop key="get*">PROPAGATION_REQUIRED,readOnly</prop>
<prop key="save*">PROPAGATION_REQUIRED</prop>
<prop key="delete*">PROPAGATION_REQUIRED</prop>
</props>
</property>
</bean>
This is one way to do it, thank you Colin (http://blog.exis.com/colin/archives/2004/07/31/concise-transaction-definitions-spring-11/)!!!
4. configure myDAO (no changes required!!!)
<bean id="myDAO" parent="txProxyTemplate">
<property name="target">
<bean class="MyDAO">
<property name="sessionFactory"><ref local="sessionFactory"/></property>
</bean>
</property>
</bean>