As someone else said Soundcloud is great for listening to full sets 🙂 Because not all DJs are producers they won't always have their own music or songs to listen to so Spotify likely not your best bet. A lot of DJs will have radio shows though which is a good place to start, and those will be posted on soundcloud. Not sure what kind of thing you're after but the Hessle Audio trio (Ben UFO, Pangaea and Pearson Sound) will all have loads of sets on Soundcloud for example. Amaliah has a really good radio show on Rinse Fm.
If you let me know the kind of thing you like (house, techno, garage etc.) I'd be more than happy to suggest some things off the line up that you might like!