public class Node {
    String ip;
    public Node(String ip){
        this.ip = ip;
    }
}
public class ConsistentHashElegent {
    private SortedMap<Integer,Node> hashCircle = new TreeMap<>();
    public ConsistentHashElegent(Node[] nodes, int virualNums){
        for (Node node :  nodes){
            for (int i = 0;i<virualNums;i++){
                hashCircle.put(this.getHash(node.toString() + i),node);
            }
        }
    }
    public Node getConsistentNode(String key) {
        int hash = getHash(key);
        //得到大于该Hash值的所有Map
        SortedMap<Integer, Node> tailMap = hashCircle.tailMap(hash);
        hash = tailMap.isEmpty()? hashCircle.firstKey() : tailMap.firstKey();
        return hashCircle.get(hash);
    }
    //使用FNV1_32_HASH算法计算服务器的Hash值
    private int getHash(String str){
        int p = 16777619;
        int hash = (int) 2166136261L;
        for (int i = 0; i < str.length(); i++){
            hash = (hash ^ str.charAt(i)) * p;
        }
        hash += hash << 13;
        hash ^= hash >> 7;
        hash += hash << 3;
        hash ^= hash >> 17;
        hash += hash << 5;
        return hash;
    }
    public static void main(String[] args){
        Node[] nodes = {new Node("192.168.1.1"),new Node("192.168.1.2"),new Node("192.168.1.3")};
        ConsistentHashElegent consistentHashElegent = new ConsistentHashElegent(nodes,5);
        Node consistentNode = consistentHashElegent.getConsistentNode("123");
        System.out.println(consistentNode);
    }
}