java中如何获取文件MD5值

??????MD5?,????Java?MessageDigest???????????:

import java.io.FileInputStream;
import java.io.IOException;
import java.security.DigestInputStream;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
public class FileMD5Checksum {
public static String getFileMD5(String filePath) {
try {
MessageDigest md = MessageDigest.getInstance("MD5");
FileInputStream fis = new FileInputStream(filePath);
DigestInputStream dis = new DigestInputStream(fis, md);
byte[] buffer = new byte[1024];
while (dis.read(buffer) != -1) {
// ????????????MD5?
}
dis.close();
byte[] digest = md.digest();
StringBuilder sb = new StringBuilder();
for (byte b : digest) {
sb.append(String.format("x", b & 0xff));
}
return sb.toString();
} catch (NoSuchAlgorithmException | IOException e) {
e.printStackTrace();
return null;
}
}
public static void main(String[] args) {
String filePath = "path/to/file";
String md5 = getFileMD5(filePath);
System.out.println("File MD5: " + md5);
}
}

??????filePath???????????????,????????MD5??