Java多進程與ZooKeeper服務發現

在Java中實現多進程與ZooKeeper服務發現通常需要使用ZooKeeper客戶端庫來與ZooKeeper集群進行交互。以下是一個簡單的示例代碼，演示如何在Java中實現多進程與ZooKeeper服務發現：

import org.apache.zookeeper.CreateMode;
import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.ZooDefs.Ids;
import org.apache.zookeeper.ZooKeeper;

import java.util.List;

public class ZooKeeperServiceDiscovery {

    private static final String ZOOKEEPER_HOST = "localhost:2181";
    private static final String SERVICE_PATH = "/services";

    private ZooKeeper zooKeeper;

    public ZooKeeperServiceDiscovery() throws Exception {
        zooKeeper = new ZooKeeper(ZOOKEEPER_HOST, 5000, new Watcher() {
            @Override
            public void process(WatchedEvent event) {
                // Handle ZooKeeper events
            }
        });
    }

    public void registerService(String serviceName, String serviceAddress) throws Exception {
        String serviceNode = SERVICE_PATH + "/" + serviceName;
        if (zooKeeper.exists(serviceNode, false) == null) {
            zooKeeper.create(serviceNode, serviceAddress.getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL);
        }
    }

    public List<String> discoverServices(String serviceName) throws Exception {
        String serviceNode = SERVICE_PATH + "/" + serviceName;
        return zooKeeper.getChildren(serviceNode, false);
    }

    public void close() throws Exception {
        zooKeeper.close();
    }

    public static void main(String[] args) throws Exception {
        ZooKeeperServiceDiscovery discovery = new ZooKeeperServiceDiscovery();
        
        // Register a service
        discovery.registerService("exampleService", "localhost:8080");
        
        // Discover services
        List<String> services = discovery.discoverServices("exampleService");
        for (String service : services) {
            System.out.println("Discovered service: " + service);
        }
        
        discovery.close();
    }

}

在上面的示例中，我們首先創建了一個ZooKeeperServiceDiscovery類，該類封裝了與ZooKeeper的交互操作。在main方法中，我們創建了一個ZooKeeperServiceDiscovery實例，并使用registerService方法注冊了一個服務，并使用discoverServices方法發現了該服務。最后關閉了ZooKeeper連接。

需要注意的是，ZooKeeper服務發現在實際項目中常常結合使用其他框架或工具來實現更復雜的功能，比如使用Spring Cloud等。同時，需要確保ZooKeeper集群的正常運行，并考慮一些異常情況的處理。