3 Mob XP Farm

It's a long, tough day. You've just arrived at your home after a day of exploring. You found some desert temple, inside of which there is several enchanted book contained. You were happy, but now you realized you don't have enough XP to apply it to your beloved tools and armors. What you can do? You know there is a mob spawner just nearby, but you don't know how to make it so you can gain XP easily without getting hurt. Well worry not players! I, Ironcraft, am here to show you 3 different mob XP Farm design that you can make!