Universities usually have certain rules and requirements for students' images and services, including decorations and hairstyles. Each school may have different rules for boys to have long hair, but in general, the following methods can help boys hide their long hair:

1. Hairstyle choice: You can choose some low-key and simple hairstyles, such as combing your long hair in a ponytail or doing it neatly, which will make it look cleaner.

2. Use hair accessories: Boys can consider using hair accessories to control long hair. Hair accessories such as hairband, hairpin or headband can be used to tie up or fix long hair to make it more tidy.

3. Hair wax or gel: You can use styling products such as hair wax or gel to help control long hair. By using these products, you can fix your long hair at the back of your head, or guide it in one direction to make your hair more tidy.

4. Hat or hat: You can choose to wear a hat or hat to hide your long hair. The hat can effectively cover the long hair, and at the same time, it can also increase the fashion sense of the overall shape.

Please note that the above are just some suggestions. It is best to decide how to deal with your hairstyle according to the regulations and requirements of your school. If the school clearly stipulates that boys are not allowed to have long hair, try to abide by the relevant regulations so as not to cause unnecessary trouble. At the same time, students can also consult the relevant departments of the school to understand the specific requirements of the school for hairstyles.