package class2.zookeeper.loadbalance;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Random;
import java.util.Set;

/**
 * 加權隨機載均衡演算法
 * @author guoy
 *
 */
public class TestWeightRandom {
    
    static
 
 Map<String,Integer> serverWeigthMap  = new HashMap<String,Integer>();

     static{
        serverWeigthMap.put("192.168.1.12", 1);
        serverWeigthMap.put("192.168.1.13", 1);
        serverWeigthMap.put("192.168.1.14", 2);
        serverWeigthMap.put("192.168.1.15", 2);
        serverWeigthMap.put(
 
"192.168.1.16", 3);
        serverWeigthMap.put("192.168.1.17", 3);
        serverWeigthMap.put("192.168.1.18", 1);
        serverWeigthMap.put("192.168.1.19", 2);
    }

    public static String weightRandom()
    {
        //重新建立一個map,避免出現由於伺服器上線和下線導致的並發問題
        Map<String,Integer> serverMap  = new
 
 HashMap<String,Integer>();
        serverMap.putAll(serverWeigthMap);
        //獲取ip列表list
        Set<String> keySet = serverMap.keySet();
        Iterator<String> it = keySet.iterator();

        List<String> serverList = new ArrayList<String>();

        while (it.hasNext()) {
            String server = it.next();
            Integer weight = serverMap.get(server);
            for (int i = 0; i < weight; i++) {
                serverList.add(server);
            }
        }        
        Random random = new Random();
        int randomPos = random.nextInt(serverList.size());
        
        String server = serverList.get(randomPos);
        return server;
    }
    
    public static void main(String[] args) {
        String serverIp = weightRandom();
        System.out.println(serverIp);
    }
}