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import java.io.InputStream;
import java.net.URL;
import java.security.MessageDigest;
public class Main {
public static void main(String[] args) throws Exception {
URL source = new URL("http://www.a.com");
URL mirror = new URL("http://www.b.com");
byte[] sourceDigest = getDigestFromURL(source);
byte[] mirrorDigest = getDigestFromURL(mirror);
if (MessageDigest.isEqual(sourceDigest, mirrorDigest)) {
System.out.println(mirror + " is up to date");
} else {
System.out.println(mirror + " needs to be updated");
}
}
public static byte[] getDigestFromURL(URL u) throws Exception {
MessageDigest md5 = MessageDigest.getInstance("MD5");
InputStream in = u.openStream();
byte[] data = new byte[1024];
int bytesRead = -1;
while ((bytesRead = in.read(data)) >= 0) {
md5.update(data, 0, bytesRead);
}
return md5.digest();
}
}
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