Shulou(Shulou.com)05/31 Report--

This article introduces how the java implementation of the consistent hash algorithm is, the content is very detailed, interested friends can refer to it, I hope it can be helpful to you.

Today we use java to implement the consistent hash algorithm, focusing on two aspects: consistency and virtual nodes.

Cut the crap and go straight to the code:

Public class ConsistencyHash {

Private TreeMap nodes = null

Private List shards = new ArrayList ()

Private int VIRTUAL_NUM = 4

Public void init () {

Shards.add ("10.10.0.0-Server 0")

Shards.add ("10.10.0.1-Server 1")

Shards.add ("10.10.0.2-Server 2")

Shards.add ("10.10.0.3-Server 3")

Shards.add ("10.10.0.4-Server 4")

Nodes = new TreeMap ()

For (int I = 0; I < shards.size (); iTunes +) {

String shardInfo = shards.get (I)

For (int j = 0; j < VIRTUAL_NUM; jacks +) {

Byte [] md5Value = computeMd5 ("SHARD-" + I + "- NODE-" + j)

Long hashCode = hash (md5Value, j)

System.out.println (hashCode)

Nodes.put (hashCode, shardInfo)

}

}

Iterator iter = nodes.keySet () .iterator ()

While (iter.hasNext ()) {

Long key = iter.next ()

String obj = (String) nodes.get (key)

System.out.println (String.valueOf (key) + ":" + obj)

}

}

Public Object getShardInfo (long hash) {

Long key = hash

SortedMap tailMap = nodes.tailMap (key)

If (tailMap.isEmpty ()) {

Key = nodes.firstKey ()

} else {

Key = tailMap.firstKey ()

}

Return nodes.get (key)

}

Public void printMap () {

System.out.println (nodes)

}

Public long hash (byte [] digest, int nTime) {

Long rv = (long) (digest [3 + nTime * 4] & 0xFF)

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