AT+FTPRETR="heyunfei.txt"
AT+FTPRETR="heyunfei.txt"
AT+FTPRETR="heyunfei.txt"
AT+FTPOPEN="39.108.157.65","ftptest","ftptest"
AT+FTPCWD="testdir0811"
AT+FTPRETR="heyunfei.txt"
AT+GTFCLOSE=1025
AT+GTFCLOSE=1025
AT+GTFCLOSE=1025
AT+GTFCLOSE=1025
AT+GTFWRITE=1025,"585858523423423441111118"
AT+GTFWRITE=1025,"585858523423423441111118"