一致性 hash 算法及实现

package leetcode;
import java.util.*;
/**
 * 一致性Hash算法实现
 */
public class ConsistencyHash {
    private static SortedMap<Integer, String> sortedMap = new TreeMap<>();
    private List<String> nodeList;
    public ConsistencyHash(List<String> nodeList) {
        this.nodeList = nodeList;
        nodeList.forEach(x -> {
            addNode(x);
        });
    }
    private void addNode(String node) {
        if (node == null) {
            return;
        }
        int hash = getHash(node);
        sortedMap.put(hash, node);
        System.out.println("hash  = " + hash  + " , node = " + node);
    }
    /**
     * 使用FNV1_32_HASH算法计算服务器的Hash值,这里不使用重写hashCode的方法，最终效果没区别
     */
    private static 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 static String getSever(String node){
        // 得到带路由的结点的Hash值
        int hash = getHash(node);
        // 得到大于该Hash值的所有Map
        SortedMap<Integer,String> sMap = sortedMap.tailMap(hash);
        // 第一个Key就是顺时针过去离node最近的那个结点
        Integer k = sMap.firstKey();
        // 返回对应的服务器名称
        return sMap.get(k);
    }
}

package leetcode;
import java.util.Arrays;
import java.util.List;
/**
 * 致性Hash算法调用
 */
public class Main {
    public static void main(String[] args) {
        String[] list = {"192.168.0.0:111", "192.168.0.1:111", "192.168.0.2:111",
                "192.168.0.3:111", "192.168.0.4:111"};
        List<String> nodeList = Arrays.asList(list);
        //初始化
        ConsistencyHash hash = new ConsistencyHash(nodeList);
        nodeList.forEach(x->{
            System.out.println(" server : " + ConsistencyHash.getSever(x));
        });
    }
}