<p>I'm currently looking for ways to create automated tests for a <a href="https://jsr311.dev.java.net/" rel="noreferrer">JAX-RS</a> (Java API for RESTful Web Services) based web service. </p>

<p>I basically need a way to send it certain inputs and verify that I get the expected responses. I'd prefer to do this via JUnit, but I'm not sure how that can be achieved.</p>

<p>What approach do you use to test your web-services?</p>

<p><strong>Update:</strong> As entzik pointed out, decoupling the web service from the business logic allows me to unit test the business logic. However, I also want to test for the correct HTTP status codes etc.</p>

You probably wrote some java code that implements your business logic and then you have generated the web services end point for it.
An important thing to do is to independently test your business logic. Since it's pure java code you can do that with regular JUnit tests.
Now, since the web services part is just an end point, what you want to make sure is that the generated plumbing (stubs, etc) are in sync with your java code. you can do that by writing JUnit tests that invoke the generated web service java clients. This will let you know when you change your java signatures without updating the web services stuff.
If your web services plumbing is automatically generated by your build system at every build, then it may not be necessary to test the end points (assuming it's all properly generated). Depends on your level of paranoia.