基础知识：

MessageDigest

FileInputStream

技巧while((len=in.read(buffer,0,1024))!=-1){

}

BigInteger


publicstaticStringgetFileMD5(Filefile){if(!file.isFile()){returnnull;}MessageDigestdigest=null;FileInputStreamin=null;bytebuffer[]=newbyte[1024];intlen;try{digest=MessageDigest.getInstance("MD5");in=newFileInputStream(file);while((len=in.read(buffer,0,1024))!=-1){digest.update(buffer,0,len);}in.close();}catch(Exceptione){e.printStackTrace();returnnull;}BigIntegerbigInt=newBigInteger(1,digest.digest());returnbigInt.toString(16);}