ValidationEventHandler via Jaxb2Marshaller via StaxEventItemReader

[RobertGloverJr]

What I need is a suggestion for how to pass a List between a StaxEventItemReader and the "handleEvent(ValidationEvent event)" of a Jaxb2Marshaller. The only solution I can think of is to use a ThreadLocal (I'm using SimpleAsyncTaskExecutor). Does that seem like the best way to do this?.

The step is in a job I configured that is reading XML via org.springframework.batch.item.xml.StaxEventItemRe ader.

I configured the "SetUnmarshaller " method of StaxEventItemReader to unmarshall via org.springframework.oxm.jaxb.Jaxb2Marshaller, and I configured that Jaxb2Marshaller to use an implementation of the javax.xml.bind.ValidationEventHandler interface that I wrote.

When there is an XML schema violation in an xml input fragment, the "handleEvent(ValidationEvent event)" method is invoked by org.springframework.oxm.jaxb.Jaxb2Marshaller.

Within that "handleEvent(...)" I accumulate information about the XML errors into a List.

I want to make that List accessible to the StaxEventItemReader so that the StaxEventItemReader can put the List into the Execution context.

Is a ThreadLocal the best way to do this?

[Dave Syer]

ThreadLocal is a last resort I would say. When you say the StaxEventItemReader is going to stash the list in the ExecutionContext, I assume you mean your custom item reader is going to do that? Can't you just inject the ValidationEventHandler (or a common component between the two) into the reader?

[RobertGloverJr]

Can't you just inject the ValidationEventHandler (or a common component between the two) into the reader?

Wow! I never thought of the approach you suggested. It sounds perfect. I will try doing it that way.

I wonder though if my plan to use "scope=step" on both "myCustomReader" as well as on "myCustCommonComponent"
is the right way to use the "step" scope. (see proposed code example below)

<bean id="myCustomReader" scope="step"
class="foo.MyCustomReader">
    <property name="myCustCommonComponent"  ref="myCustCommonComponent" />
    ...other configs...
</bean>

<bean id="myCustCommonComponent" class="foo.MyCustCommonComponent" scope="step"
    ... configs ....
</bean>

[Dave Syer]

Anything stateful should be step-scoped. You can do that by explicitly declaring scope="step" as in your example, or by declaring a component as an inner bean of a step-scoped component which is not relevant here.