轮询法

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public class TestRoundRobin {
  private static Map<String, Integer> serverWeightMap = new HashMap<>();
  
  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 static String roundRobin() {
    Map<String, Integer> serverMap = new HashMap<>();
    serverMap.putAll(serverWeightMap);
    Set<String> keySet = serverMap.keySet();
    ArrayList<String> keyList = new ArrayList<>();
    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) {
    for (int i = 0; i < 20; i++) {
      String serverIp = roundRobin();
      System.out.println(serverIp);
    }
  }
}

加权轮询

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public class TestWeightRandom {
  private static Map<String, Integer> serverWeightMap = new HashMap<>();
  
  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() {
    Map<String, Integer> serverMap = new HashMap<>();
    serverMap.putAll(serverWeightMap);
    Set<String> keySet = serverMap.keySet();
    Iterator<String> it = keySet,iterator();
    List<String> serverList = new ArrayList<>();
    
    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);
  }
}