使用 Java 对 FTP 文件进行校验和

Question

I'm have created a java app which transfers files from FTP location to HDFS. This is done using copying the file first to temp folder in the edge node then move it to HDFS (cloudera cluster). Currently I'm doing byte check on the file - I'm comparing total file size in bytes of the FTP file and the copied HDFS file. I want to implement checksum. I have googled but I couldn't get any answers. Please let me know if you any ideas. (FTP server is a Windows machine where we enabled FTP)

Answer 1

If you want to calculate checksum, I think that the easiest solution is to use Apache Common Codec.

String sha256hex = org.apache.commons.codec.digest.DigestUtils.sha256Hex(stringText); 

Another alternative is Guava which has an easy-to-use suite of Hashing utilities. For example, to hash a string using SHA256 as a hex-string you would simply do:

final String hashed = Hashing.sha256()
        .hashString("your input", StandardCharsets.UTF_8)
        .toString();