一致性哈希java TreeMap实现

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package cn.ceopen.shard.utils;

import java.util.ArrayList;
import java.util.List;
import java.util.SortedMap;
import java.util.TreeMap;

import org.apache.commons.codec.digest.DigestUtils;

/**
 * 一致性hash实现
 * @author 徐良永
 *
 * 2015年1月22日 下午2:34:05
 */
public class ConsistantHash2 {

	//圆环  用treemap的主要原因是可以排序
	private TreeMap circle = new TreeMap();
	
	//真实结点
	private List realNodes = new ArrayList();
	
	public static void main(String[] args) {
		ConsistantHash2 h = new ConsistantHash2();
		h.addNode(new Node(1));
		h.addNode(new Node(2));
//		h.addNode(new ConsistentHash.Node(3));
//		h.addNode(new ConsistentHash.Node(4));
//		h.addNode(new ConsistentHash.Node(5));
//		h.addNode(new ConsistentHash.Node(6));
//		h.addNode(new ConsistentHash.Node(7));
//		h.addNode(new ConsistentHash.Node(8));
//		h.addNode(new ConsistentHash.Node(9));
		
		for (int i = 0; i < 50; i++) {
			h.getNode("" + i);
			//System.out.println(i + "--->" + h.getNode("" + i));
		}
	}
	
	
	public void addNode(Node node){
		realNodes.add(node);
		
		Long nodeKey = md5(node.toString());
		System.out.println(node.toString() + " md5:" + nodeKey);
		circle.put(nodeKey, node);
	}
	
	public void removeNode(Node node){
		realNodes.remove(node);
		
		Long nodeKey = md5(node.toString());
		circle.remove(nodeKey);
	}
	
	/**
	 * 
	 * @param key
	 * @return
	 */
	public Node getNode(String key){
		//treemap 转成 排序好的map
		Long keyMd5 = md5(key);
		SortedMap sortedMap = circle.tailMap(keyMd5);
		Long k = null;
		
		//没命中则选择第一个
		if(sortedMap.isEmpty()){
			k = (circle.firstKey());
			System.out.println("not hit");
		}else{
			k = (sortedMap.firstKey());
		}
		Node node = circle.get(k);
		
		//正常情况下 md5(key) < md5(node)
		System.out.println(key + "(" + keyMd5 +") --->" + node.toString() + "(" + md5(node.toString()) + ")");
		return node;
	}
	
	private long md5(String key){
		byte[] bKey = DigestUtils.md5(key.getBytes());
		long res = ((long) (bKey[3] & 0xFF) << 24) | ((long) (bKey[2] & 0xFF) << 16) | ((long) (bKey[1] & 0xFF) << 8)| bKey[0] & 0xFF;  
	    return res;  
	}
	
	static class Node{
		private int nodeNum;
		
		public Node(int num){
			this.nodeNum = num;
		}
		
		@Override
		public String toString(){
			return "真实结点:" + nodeNum ;
		}
	}
}