JAXB marshaling: how to include exceptions info into xml output file?

I have a very basic application that uses JAXB marshaller to validate input information against an xsd schema. I register a validation event handler to obtain information about the exceptions. What I would like to achieve is the ability to include this information into xml output structure I receive as a result of marshaling. I’ve included excepti开发者_运维百科on collection section into my xsd and now I can instantiate the corresponding exception object once an exception is encountered. The question is how do I attach this object to the rest of my JAXB generated Java objects structure considering the fact that marshaling process had already started? Is it even possible? Or should I try and modify the xml result after the marshaling is done? Any advice would be highly appreciated. Thanks!

There a couple of ways to do this:

Option #1 - Add an "exceptions" Property to You Root Object

1. Ensure that the exceptions property is marshalled last, this can be configured using propOrder on the @XmlType annotation.
2. Create a validation handler that holds onto the root object.
3. When the validation handler encounters an exception, add that exception to the exceptions property on the root object.

Option #2 - Use an XMLStreamWriter

1. Create an XMLStreamWriter
2. Write out a root element
3. Set the validation handler on the marshaller, ensure that it will store the exceptions encountered.
4. Marshal the root object to the XMLStreamWriter.
5. Marshal the individual exceptions encountered to the XMLStreamWriter.
6. Write out the close for the root element.

Short answer: no. JAXB is intended to take an object graph and produce XML. it's not intended to do this.

Longer answer: You could inject the exception representation into the graph after JAXB is done the first time.

Even longer answer: There are a number of plugin and customization technologies for JAX-B, and it's possible that you could use one of them. However, it's very hard to conceptualize this at the abstract level of your question.