How to convert multiple POJOs to xml in required format?

We've requirement where we need to generate XML file for sending it to another system. I was l开发者_如何转开发ooking at this example (which uses JAXB).

http://thomassundberg.wordpress.com/2010/01/19/how-to-convert-a-pojo-to-xml-with-jaxb/

However, this one converts only single POJO to xml whereas we have multiple POJOs e.g. Car/Wheel/Seats etc. that should appear in xml.

Any idea on how this can be achieved?

e.g. I would like to have something like this as final output

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<car registration="abc123">
    <brand>Volvo</brand>
    <description>Sedan</description>

    <wheel>
      <brand>Ceat</brand>     
    </wheel>
</car>

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It sounds like you're trying to convert a graph of Java objects to XML, which JAXB can do. Each object in the graph should have JAXB annotations. See http://numberformat.wordpress.com/2009/11/01/using-jaxb-to-convert-between-xml-and-pojos/.

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If you have multiple instances of the same POJO class, you can create a List of them and convert that to XML, remembering that you need to wrap the list in a root element.

If you have multiple POJO classes then you can create a wrapper class to hold them and convert that to XML.

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Castor to the rescue.

The link used to be to castor.org. That site appears to have gone away. Link updated compliments of Matt Ball (see comments below).

Castor Intro Info