Java で負荷分散を実装するためのいくつかのアルゴリズム コードの詳細な説明

package class2.zookeeper.loadbalance;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;

/**
 * 負載均衡算法，輪詢法
 * @author guoy
 *
 */
public class TestRoundRobin {

  
  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);
  }
   Integer pos = 0;
   public String roundRobin()
    {
      //重新建立一個map,避免出現由於服務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();
      ArrayList<String> keyList = new ArrayList<String>();
      keyList.addAll(keySet);
      
      String server = null;
      
      synchronized (pos) {
        if(pos >=keySet.size()){
          pos = 0;
        }
        server = keyList.get(pos);
        pos ++;
      }
      return server;
    }
    
    public static void main(String[] args) {
      TestRoundRobin robin = new TestRoundRobin();
      for (int i = 0; i < 20; i++) {
        String serverIp = robin.roundRobin();
        System.out.println(serverIp);
      }
    }
}

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;

/**
 * 加權隨機载均衡算法
 * @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,避免出現由於服務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);
  }
}

package class2.zookeeper.loadbalance;

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

/**
 * 隨機负载均衡算法
 * @author guoy
 *
 */
public class TestRandom {
  
  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 random()
  {
    //重新建立一個map,避免出現由於服務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();
    ArrayList<String> keyList = new ArrayList<String>();
    keyList.addAll(keySet);
    
    Random random = new Random();
    int randomPos = random.nextInt(keyList.size());
    
    String server = keyList.get(randomPos);
    return server;
  }
  
  public static void main(String[] args) {
    String serverIp = random();
    System.out.println(serverIp);
  }
}