call function 'SPLIT_FILENAME' "函数:拆分文件绝对路径
exporting
long_filename = l_local_file_path "文件绝对路径 C://DOC/TEST.TXT
importing
pure_filename = l_pure_filename "文件名称（不带后缀） C://DOC/TEST
pure_extension = l_pure_extension. "文件后缀TXT
或者：
FORM getfiletype USING filename TYPE localfile filetype TYPE c.
DATA: len TYPE i,
pos TYPE i,
char TYPE c.
len = STRLEN( filename ).
pos = len.
DO len TIMES.
pos = pos - 1.
char = filename+pos(1).
IF char ='.'.
len = len - pos.
pos = pos + 1.
filetype = filename+pos(len).
TRANSLATE filetype TO UPPER CASE.
EXIT.
ENDIF.
ENDDO.
ENDFORM.
