io.polaris.core.hash.KetamaHash Maven / Gradle / Ivy
package io.polaris.core.hash;
import io.polaris.core.lang.primitive.Bytes;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
/**
* Ketama算法，用于在一致性Hash中快速定位服务器位置
*
* @author Qt
* @since 1.8, Aug 01, 2023
*/
public class KetamaHash {
public static long hash64(String key) {
byte[] bKey = md5(key);
return ((long) (bKey[3] & 0xFF) << 24)
| ((long) (bKey[2] & 0xFF) << 16)
| ((long) (bKey[1] & 0xFF) << 8)
| (bKey[0] & 0xFF);
}
public static int hash32(String key) {
return (int) (hash64(key) & 0xffffffffL);
}
public static long hash(String key) {
return hash64(key);
}
/**
* 计算MD5值，使用UTF-8编码
*
* @param key 被计算的键
* @return MD5值
*/
private static byte[] md5(String key) {
final MessageDigest md5;
try {
md5 = MessageDigest.getInstance("MD5");
} catch (NoSuchAlgorithmException e) {
throw new IllegalArgumentException("MD5 algorithm not support!", e);
}
return md5.digest(Bytes.utf8Bytes(key));
}
}