WS_QUERY的QUERY是'DE'
CALLMETHODcl_gui_frontend_services=>directory_exist
WS_QUERY的QUERY是'FE'
CALL METHODcl_gui_frontend_services=>file_exist
WS_QUERY的QUERY是'FL'
CALL
METHODcl_gui_frontend_services=>file_get_size
注意：后面加上CALLMETHOD
cl_gui_cfw=>flush().