一致性算法实现

public class ConsistenceHashWithVnNode {
    private static final String VN_FLAG = "&&vn";
    /** 真实节点 */
    private List<String> realNodes;
    /** 虚拟节点的数量 */
    private int vnNodeCount;
    /** 虚拟节点 */
    private TreeMap<Integer,String> vnNodes = new TreeMap<Integer, String>();
    public ConsistenceHashWithVnNode(List<String> realNodes,int vnNodeCount){
        this.realNodes = realNodes;
        this.vnNodeCount = vnNodeCount;
        // 初始化
        initVnNode();
    }
    private void initVnNode() {
        for (String realNode : realNodes) {
            for (int i = 0; i < vnNodeCount; i++) {
                String vnNodeName = realNode + VN_FLAG;
                int hash = getHash(vnNodeName);
                vnNodes.put(hash,vnNodeName);
                System.out.println("添加虚拟节点 hash = "+hash+", vnNodeName = "+ vnNodeName);
            }
        }
    }
    /** 使用FNV1_32_HASH算法计算服务器的Hash值 */
    private int getHash(String str) {
        final 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;
        // 如果算出来的值为负数则取其绝对值
        if (hash < 0)
                hash = Math.abs(hash);
        return hash;
    }
    public String getServer(String node){
        int hash = getHash(node);
        Map.Entry<Integer, String> entry = vnNodes.ceilingEntry(hash);
        if(entry == null){
            entry = vnNodes.firstEntry();
        }
        String vnNode = entry.getValue();
        return vnNode.substring(0,vnNode.lastIndexOf(VN_FLAG));
    }
}

public class Test {
    
    public static void main(String[] args) {
        List<String> servers = new LinkedList<>();
        servers.add("192.168.0.1:111");
        servers.add("192.168.0.2:111");
        servers.add("192.168.0.3:111");
        servers.add("192.168.0.4:111");
        servers.add("192.168.0.5:111");
        ConsistenceHashWithVnNode consistenceHashWithVnNode = new ConsistenceHashWithVnNode(servers, 10000);
        int count = 1000000;
        Map<String,Integer> map = new HashMap<>();
        for (int i = 0; i < count; i++) {
            String randomIp = getRandomIp();
            String server = consistenceHashWithVnNode.getServer(randomIp);
            doCount(map,server);
        }
        map.forEach((key,value)->{
            System.out.println("server: "+key+", count = "+ value );
        });
    }
    public static String getRandomIp() {
        // ip范围
        int[][] range = {
                {607649792, 608174079}, // 36.56.0.0-36.63.255.255
                {1038614528, 1039007743}, // 61.232.0.0-61.237.255.255
                {1783627776, 1784676351}, // 106.80.0.0-106.95.255.255
                {2035023872, 2035154943}, // 121.76.0.0-121.77.255.255
                {2078801920, 2079064063}, // 123.232.0.0-123.235.255.255
                {-1950089216, -1948778497}, // 139.196.0.0-139.215.255.255
                {-1425539072, -1425014785}, // 171.8.0.0-171.15.255.255
                {-1236271104, -1235419137}, // 182.80.0.0-182.92.255.255
                {-770113536, -768606209}, // 210.25.0.0-210.47.255.255
                {-569376768, -564133889}, // 222.16.0.0-222.95.255.255
        };
        Random random = new Random();
        int index = random.nextInt(10);
        String ip = num2ip(range[index][0] + new Random().nextInt(range[index][1] - range[index][0]));
        return ip;
    }
    /*
     * 将十进制转换成IP地址
     */
    public static String num2ip(int ip) {
        int[] b = new int[4];
        String ipStr = "";
        b[0] = (int) ((ip >> 24) & 0xff);
        b[1] = (int) ((ip >> 16) & 0xff);
        b[2] = (int) ((ip >> 8) & 0xff);
        b[3] = (int) (ip & 0xff);
        ipStr = Integer.toString(b[0]) + "." + Integer.toString(b[1]) + "." + Integer.toString(b[2]) + "." + Integer.toString(b[3]);
        return ipStr;
    }
    private static void doCount(Map<String,Integer> map , String server) {
        Integer count = map.getOrDefault(server, 0);
        map.put(server,count+1);
    }
}

server: 192.168.0.1:111, count = 383832
server: 192.168.0.2:111, count = 8760
server: 192.168.0.3:111, count = 331552
server: 192.168.0.4:111, count = 199585
server: 192.168.0.5:111, count = 76271