java 实现一致性 hash 算法

public interface LoadBalancer {    String select(List<String> serverName, String requestUrl);}

public interface HashStrategy {    int getHashCode(String requestUrl);}

public class VirtualNodeConsistentHash implements LoadBalancer{    private final static int VIRTUAL_NODE_SIZE = 16;    private final static String VIRTUAL_NODE_SUFFIX = "&&";
    private HashStrategy hashStrategy = new MurmurHashStrategy();
    @Override    public String select(List<String> servers, String requestUrl) {        int hashCode = hashStrategy.getHashCode(requestUrl);        TreeMap<Integer, String> hashRing = buildHashRing(servers);
        Map.Entry<Integer, String> entry = hashRing.ceilingEntry(hashCode);        if (entry == null) {            entry = hashRing.firstEntry();        }        return entry.getValue();    }
    public TreeMap<Integer, String> buildHashRing(List<String> servers) {        TreeMap<Integer, String> virtualNodeRing = new TreeMap<>();        for (String server : servers) {            for (int i = 0; i < VIRTUAL_NODE_SIZE; i++) {                virtualNodeRing.put(hashStrategy.getHashCode(server + VIRTUAL_NODE_SUFFIX + i), server);            }        }        return virtualNodeRing;    }}

public class MurmurHashStrategy implements HashStrategy {    @Override    public int getHashCode(String requestUrl) {        HashFunction murmur3 = Hashing.murmur3_32();        HashCode murmur3HashCode = murmur3.hashString(requestUrl, Charsets.UTF_8);        int result = murmur3HashCode.asInt();        return result;    }
    public static void main(String[] args) {        MurmurHashStrategy m = new MurmurHashStrategy();        System.out.println( m.getHashCode("1231234"));;    }}

public class TestMain {    private static VirtualNodeConsistentHash virtualNodeConsistentHash = new VirtualNodeConsistentHash();    private static TreeMap<Integer, String> virtualNodeRing;    private static List<String> servers = Lists.newArrayList();
    private static void init() {        for (int i = 0; i < 10; i++) {            StringBuilder stringBuilder = new StringBuilder();            servers.add(stringBuilder.append("192.168.0.").append(String.valueOf(i)).toString());        }        virtualNodeRing = virtualNodeConsistentHash.buildHashRing(servers);    }
    private static List<String> getIPAddress(int num) {        List<String> res = Lists.newArrayList();        Random random = new Random();        for (int i = 0; i < num; i++) {            String ip = String.valueOf(random.nextInt(256)) + "." + String.valueOf(random.nextInt(256)) + "."                    + String.valueOf(random.nextInt(256)) + "." + String.valueOf(random.nextInt(256));            res.add(ip);        }        return res;    }
    public static void main(String[] args) {        init();        List<String> reqNodeList = getIPAddress(99);        Map<String, String> result = Maps.newHashMap();        Map<String, Integer> statistic = Maps.newHashMap();        reqNodeList.stream()                .forEach(reqNode -> {                    String server = virtualNodeConsistentHash.select(servers, reqNode);                    result.put(reqNode, server);                    int num = statistic.getOrDefault(server, 0);                    statistic.put(server, ++num);                });
        statistic.forEach((k,v)->                System.out.println(k +" >>> " + v));    }}