How to concatenate two web.xml?

Question

I have Java project with different modules on it. The project have one core module where all the common configuration files kept. Each module has separate configuration files like .properties files, hibernate.cfg, web.xml etc. It is not necessary that every time all modules will be there on the final build.

My problem is that, suppose 3 modules such as A, B & C are present. Each has its on web.xml and it contains only the servlets and mapping necessary for that. I want to know how concatenate these web.xml while building. I know that from ant I can call a Java application. The position of tags is important in web.xml.

How it possible to concatenate these web.xml effectively? I tried xstream for this but it was a failure.

Answer 1

The xmltask is great for xmlprocessing with ant.
See details and examples here :
xmltask :
xml task manual
xml manipulation using xml task
useful xpath links :
http://zvon.org/xxl/XPathTutorial/
http://www.w3schools.com/xpath/

Answer 2

If you are using an Servlet 3.0 container, then only your core module would have a web.xml and your other modules would each provide their own web-fragment.xml.

Answer 3

There are following ways you can achieve this:

1. using xstream marshalling for your purpose; see the question on marshalling of Map for how to marshal an object. or use the official tutorial
2. Use a SAX Parsing, by manually converting it.
3. Convert the whole XML to a JSON using JSON.org and merge each of the XMLs and rebuild the XML from the JSON. NOTE: the don't use the xstream for this purpose, it reverses the whole XML, causing validation errors to the resulting XMLs.

Answer 4

Your quesion itself has answer , Write a small java program to parse all XML you want to combine , get required nodeList , write in new XML in the order you want. Call this java program during Ant build.