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Java library to initiate VWo instance for server side a/b testing
package com.vwo;
import java.nio.charset.Charset;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Objects;
import java.util.UUID;
public class UUIDType5 {
private static final Charset UTF8 = Charset.forName("UTF-8");
public static final UUID NAMESPACE_DNS = UUID.fromString("6ba7b810-9dad-11d1-80b4-00c04fd430c8");
public static final UUID NAMESPACE_URL = UUID.fromString("6ba7b811-9dad-11d1-80b4-00c04fd430c8");
public static final UUID NAMESPACE_OID = UUID.fromString("6ba7b812-9dad-11d1-80b4-00c04fd430c8");
public static final UUID NAMESPACE_X500 = UUID.fromString("6ba7b814-9dad-11d1-80b4-00c04fd430c8");
public static UUID nameUUIDFromNamespaceAndString(UUID namespace, String name) {
return nameUUIDFromNamespaceAndBytes(namespace, Objects.requireNonNull(name, "name == null").getBytes(UTF8));
}
public static UUID nameUUIDFromNamespaceAndBytes(UUID namespace, byte[] name) {
MessageDigest md;
try {
md = MessageDigest.getInstance("SHA-1");
} catch (NoSuchAlgorithmException nsae) {
throw new InternalError("SHA-1 not supported");
}
md.update(toBytes(Objects.requireNonNull(namespace, "namespace is null")));
md.update(Objects.requireNonNull(name, "name is null"));
byte[] sha1Bytes = md.digest();
sha1Bytes[6] &= 0x0f; /* clear version */
sha1Bytes[6] |= 0x50; /* set to version 5 */
sha1Bytes[8] &= 0x3f; /* clear variant */
sha1Bytes[8] |= 0x80; /* set to IETF variant */
return fromBytes(sha1Bytes);
}
private static UUID fromBytes(byte[] data) {
// Based on the private UUID(bytes[]) constructor
long msb = 0;
long lsb = 0;
assert data.length >= 16;
for (int i = 0; i < 8; i++) {
msb = (msb << 8) | (data[i] & 0xff);
}
for (int i = 8; i < 16; i++) {
lsb = (lsb << 8) | (data[i] & 0xff);
}
return new UUID(msb, lsb);
}
private static byte[] toBytes(UUID uuid) {
// inverted logic of fromBytes()
byte[] out = new byte[16];
long msb = uuid.getMostSignificantBits();
long lsb = uuid.getLeastSignificantBits();
for (int i = 0; i < 8; i++) {
out[i] = (byte) ((msb >> ((7 - i) * 8)) & 0xff);
}
for (int i = 8; i < 16; i++) {
out[i] = (byte) ((lsb >> ((15 - i) * 8)) & 0xff);
}
return out;
}
}
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