Yeah, it rans a lot in July, but not every single day, and usually only for a few minutes in the afternoon (but very, very strong).
Sometimes it's a lasting rain, too, but that's the exeption.
If you are among the cogniscenti (and you are now that your have consuted these boards!), you know that the rain will scare away lots of people, and that the park is less crowded after the rain stops, so you just stick it out and enjoy the respite from the crowds.
Some people just toss on ponchos and keep going. Some duck into shops and see if the rain will pass soon (it often does).
Some people just simply don't like the rain. If you are one of these and you are staying at a nearby resort, a the rain looks like it will last a while, you can always nip back for a change of socks and shoes (and other things depending on how wet you get), have a bite, and head back to the same or a different park. Just be aware that a lot of other folk will be doing the same thing.
For me, if rain is predicted at all, we either wear sandals or bring dry socks with us, and stick it out. I view a rainstorm as an opportunity to enjoy the lack of crowds, rather than as a disapointment. Sure, some attractions will close due to safety; just do other stuff, like HOP or COP, etc. Those other attractions will open soon when the rain stops.
One way to avoid the rain most days is to get to the parks early, early in the morning. In July it almost never rains early in the day.
Have a magical trip!