What are your requirements/constraints? Do you have any security constraints? You could directly consume it in javascript/jquery using $.getjson() or server side using HTL/Sling models if you have any orchestration requirements. You could also do it in various other frameworks/libraries.
As @gauravb10066713 mentions you can write a custom AEM service that is able to use Java to consume a 3rd party RESTFul web service. In our little example - we consume a Google RESTFul service and displays the result in an AEM component.
