需求

某分布式系统中，主节点可以有多台，可以动态上下线，任意一台客户端都能实时感知到主节点服务器的上下线。

设计

ZooKeeper监听服务器节点动态上下线_主机名

实现
public class DistributeServer {

  public static void main(String[] args) throws Exception {

    DistributeServer server = new DistributeServer();

    // 1 连接zookeeper集群
    server.getConnect();

    // 2 注册节点
    server.regist(args[0]);

    // 3 业务逻辑处理
    server.business();
  }

  private void business() throws InterruptedException {

    Thread.sleep(Long.MAX_VALUE);
  }

  private void regist(String hostname) throws KeeperException, InterruptedException {

    String path = zkClient.create("/servers/server", hostname.getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL_SEQUENTIAL);

    System.out.println(hostname +"is online ");

  }

  private String connectString = "192.168.0.201:2181";
  private int sessionTimeout = 2000;
  private ZooKeeper zkClient;

  private void getConnect() throws IOException {

    zkClient = new ZooKeeper(connectString , sessionTimeout , new Watcher() {

      @Override
      public void process(WatchedEvent event) {
        try {
          getChlidren();
        } catch (KeeperException e) {
          e.printStackTrace();
        } catch (InterruptedException e) {
          e.printStackTrace();
        }
      }
    });
  }

  private void getChlidren() throws KeeperException, InterruptedException {

    List<String> children = zkClient.getChildren("/servers", true);

    // 存储服务器节点主机名称集合
    ArrayList<String> hosts = new ArrayList<>();

    for (String child : children) {

      byte[] data = zkClient.getData("/servers/"+child, false, null);

      hosts.add(new String(data));
    }

    // 将所有在线主机名称打印到控制台
    System.out.println(hosts);

  }
}


预期结果
192.168.0.103is online 
[192.168.0.105, 192.168.0.103]
[192.168.0.105, 192.168.0.201, 192.168.0.103]


作者：薄荷加冰

​版权：本文版权归作者所有