第五周 - 作业一



import java.util.HashMap;

import java.util.TreeMap;

import java.util.UUID;



public class ConsistentHash {

public static TreeMap<Integer, String> nodesMap = new TreeMap<Integer, String>();



public static void init() {

String[] nodes = new String[]{"192.168.1.0", "192.168.1.1", "192.168.1.2", "192.168.1.3", "192.168.1.4",

"192.168.1.5", "192.168.1.6", "192.168.1.7", "192.168.1.8", "192.168.1.9",};



for (String node : nodes) {

for(int i=0;i<15;i++){

//System.out.println(getHash(node+"#"+i));

nodesMap.put(getHash(node+"#"+i), node);

}

}

}



public static void addNode(String node) {

nodesMap.put(getHash(node), node);

}



public static void dropNode(String node) {

nodesMap.remove(getHash(node));

}



public static String getNode(String key) {

if(null==nodesMap.ceilingEntry(getHash(key))){

return nodesMap.firstEntry().getValue();

}

return nodesMap.ceilingEntry(getHash(key)).getValue();

}



private static int getHash(String str) {

final int p = 16777619;

int hash = (int) 2166136261L;

//System.out.println(hash);

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 void main(String[] args) {

init();

HashMap<String,Integer> count=new HashMap<String,Integer>();

for(int i=0;i<100000;i++){

String uuid= UUID.randomUUID().toString().replace("-","");

String node=getNode(uuid);

if(count.containsKey(node)){

count.replace(node,count.get(node)+1);

}else{

count.put(node,1);

}

}

System.out.println(count);

}

}