算法

最新推荐文章于 2025-12-04 16:02:12 发布

原创最新推荐文章于 2025-12-04 16:02:12 发布 · 381 阅读

0 ·

CC 4.0 BY-SA版权

文章标签：

#算法 #string #byte #java #null

ketama　清纯版（参考　http://www.metabrew.com/article/libketama-consistent-hashing-algo-memcached-clients，https://github.com/RJ/ketama/blob/master/java_ketama/SockIOPool.java）　java实现：

	/**

	 * Calculates the ketama hash value for a string 

	 * @param s

	 * @return

	 */

	public
 static
 Long
 md5HashingAlg
(
String
 key
)
 {




		if
(
md5
==
null
)
 {

			try
 {

				md5
 =
 MessageDigest
.
getInstance
(
"MD5"
);

			}
 catch
 (
NoSuchAlgorithmException
 e
)
 {

				log
.
error
(
 "++++ no md5 algorythm found"
 );

				throw
 new
 IllegalStateException
(
 "++++ no md5 algorythm found"
);
			
			}

		}




		md5
.
reset
();

		md5
.
update
(
key
.
getBytes
());

		byte
[]
 bKey
 =
 md5
.
digest
();

		long
 res
 =
 ((
long
)(
bKey
[
3
]&
0
xFF
)
 <<
 24
)
 |
 ((
long
)(
bKey
[
2
]&
0
xFF
)
 <<
 16
)
 |
 ((
long
)(
bKey
[
1
]&
0
xFF
)
 <<
 8
)
 |
 (
long
)(
bKey
[
0
]&
0
xFF
);

		return
 res
;

	}