How to generate JUnit style XML report using TestNG?

I'm using TestNG framework for our integration testing. I want to generate JUnit style XML report using TestNG. My project does not use Ant but we use Maven. Can you please tell what is the format of JUnit style XML looks like and how to generate JUnit XML files using TestNG API. Later I want to integrate this JUnit XML file with Hudson and I even want to customize this JUnit XML report using TestNG.

So How can I do the above tasks?

Can we generate JUnit report for the test cases generated in TestNG?

TestNG, by default, generates JUnit XML reports for any test execution (in the test-output folder). We can use these XML report files as input for generating a JUnit HTML report.

TestNG already generates these files, look under test-output/junitreports.