How to get File both MD5 and SHA1 checksum at the same time when upload a new file?

问题

I am working on a storage system. Users upload files to the server.

On the server side, I want to implement a program to get the checksums of the file using both MD5 and SHA1.

I know how to calculate checksums using DigestInputStream functions, but it seems only supports one method (either MD5 or SHA1) a time. How can I calculate both MD5 and SHA1 a the same time when dealing with the upload stream in JAVA?

Thanks guys

回答1:

Use two MessageDigest instances (one for MD5 and one for SHA1) and feed the bytes you read into both.

回答2:

as java-ish pseudocode, since you can look up the API for OpenSSL or BSafe or the Java Crypto API on your own...

Buffered reader = ...;
char[MY_ARRAY_SIZE] buf = ...;

while( true ) {
  int count = reader.read(buf, 0, buf.length);
  if( count == -1 ) { break };

  /* You'll need to check for the right API and handle errors yourself */
  md5.add(buf, count);
  sha256.add(buf, count);
}

String md5sum = base64(md5.finalize()); // assumes an appropriate base64 method
String sha256sum = base64(sha256.finalize());

来源：https://stackoverflow.com/questions/14610850/how-to-get-file-both-md5-and-sha1-checksum-at-the-same-time-when-upload-a-new-fi