一个屏幕小键盘程序的源码，可以直接使用。作为初学者的成果，代码可能有点小乱，有部分作了注释，读起来应该很容易。-A screen keypad program source code, can be used directly. As a result of beginners, the code may be a little messy, some comments were made, it should be easy to read.