解决方法
Jacksum：
http://www.jonelo.de/java/jacksum/index.html
- cksum algorithm: POSIX 1003.2 CRC algorithm
- length: 32 bits
- type: crc
- since: Jacksum 1.0.0
- comment: - under BeOS it is /bin/cksum
- - under FreeBSD it is /usr/bin/cksum
- - under HP-UX it is /usr/bin/cksum and
- /usr/bin/sum -p
- - under IBM AIX it is /usr/bin/cksum
- - under Linux it is /usr/bin/cksum
它是开源的.
