How to gently tell him not to send me messages? He is a classmate of mine in high school and sends me messages almost every day. What are you doing? Have you eaten?

The best way to put it is, "I want to wait until after the college entrance examination to talk about feelings." But if that boy really likes you, I'm afraid it will be even more troublesome when you finish the college entrance examination. You can consider telling him gently that you don't like him. Generally speaking, after being rejected, boys rarely make friends with girls they like. One is face and the other is embarrassment. I think you should find a suitable time to talk to him. Communication is the best way to solve problems. If you don't make a quick decision on emotional matters, the longer you wait, the more painful your heart will be, and the harder it will be to be cruel.