使用JAVA实现Curator注册的MySQL连接节点中存储的是实际的连接对象或连接状态，给出完整的注册过程实现代码，curator版本为curator-recipes5.0.0，Java版本为18，MySQL版本为8.0.21.给出完整实现代码以及使用示例。

以下是使用JAVA实现Curator注册MySQL连接节点的示例代码：

import org.apache.curator.framework.CuratorFramework;
import org.apache.curator.framework.recipes.cache.NodeCache;
import org.apache.curator.framework.recipes.cache.NodeCacheListener;
import org.apache.curator.framework.recipes.cache.PathChildrenCache;
import org.apache.curator.framework.recipes.cache.PathChildrenCacheEvent;
import org.apache.curator.framework.recipes.cache.PathChildrenCacheListener;
import org.apache.curator.framework.recipes.cache.PathChildrenCache.StartMode;
import org.apache.curator.framework.recipes.cache.PathChildrenCacheEvent.Type;
import org.apache.curator.framework.recipes.nodes.PersistentNode;
import org.apache.curator.framework.recipes.nodes.PersistentNode.Mode;
import org.apache.curator.framework.recipes.nodes.PersistentNode.StateListener;
import org.apache.curator.retry.ExponentialBackoffRetry;
import org.apache.zookeeper.CreateMode;
import org.apache.zookeeper.data.Stat;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

public class CuratorMySQLRegister {

    private static final String MYSQL_NODE_PATH = "/mysql/connection";
    private static final String MYSQL_URL = "jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=UTF-8&serverTimezone=UTC";
    private static final String MYSQL_USERNAME = "root";
    private static final String MYSQL_PASSWORD = "123456";

    private CuratorFramework client;
    private PersistentNode mysqlNode;
    private NodeCache mysqlNodeCache;
    private PathChildrenCache mysqlNodeChildrenCache;

    public CuratorMySQLRegister(String connectionString) {
        client = CuratorFrameworkFactory.newClient(connectionString, new ExponentialBackoffRetry(1000, 3));
        client.start();
        mysqlNode = new PersistentNode(client, Mode.EPHEMERAL, true, MYSQL_NODE_PATH, "mysql".getBytes());
        mysqlNode.start();
        mysqlNodeCache = new NodeCache(client, MYSQL_NODE_PATH);
        mysqlNodeCache.start(true);
        mysqlNodeChildrenCache = new PathChildrenCache(client, MYSQL_NODE_PATH, true);
        mysqlNodeChildrenCache.start(StartMode.POST_INITIALIZED_EVENT);
    }

    public void register() throws Exception {
        mysqlNode.waitForInitialCreate(3000);
        mysqlNode.addStateListener(new StateListener() {
            @Override
            public void stateChanged(CuratorFramework client, ConnectionState newState) {
                if (newState == ConnectionState.LOST) {
                    System.out.println("Connection lost");
                } else if (newState == ConnectionState.CONNECTED) {
                    System.out.println("Connection connected");
                } else if (newState == ConnectionState.RECONNECTED) {
                    System.out.println("Connection reconnected");
                }
            }
        });
        mysqlNodeCache.getListenable().addListener(new NodeCacheListener() {
            @Override
            public void nodeChanged() throws Exception {
                byte[] data = mysqlNodeCache.getCurrentData().getData();
                if (data != null) {
                    String mysqlUrl = new String(data);
                    Connection connection = DriverManager.getConnection(mysqlUrl, MYSQL_USERNAME, MYSQL_PASSWORD);
                    // 使用连接
                }
            }
        });
        mysqlNodeChildrenCache.getListenable().addListener(new PathChildrenCacheListener() {
            @Override
            public void childEvent(CuratorFramework client, PathChildrenCacheEvent event) throws Exception {
                if (event.getType() == Type.CHILD_ADDED) {
                    String mysqlUrl = new String(event.getData().getData());
                    Connection connection = DriverManager.getConnection(mysqlUrl, MYSQL_USERNAME, MYSQL_PASSWORD);
                    // 使用连接
                } else if (event.getType() == Type.CHILD_REMOVED) {
                    // 处理节点删除事件
                }
            }
        });
    }

    public void unregister() throws Exception {
        mysqlNode.close();
        mysqlNodeCache.close();
        mysqlNodeChildrenCache.close();
        client.close();
    }

    public static void main(String[] args) throws Exception {
        CuratorMySQLRegister register = new CuratorMySQLRegister("localhost:2181");
        register.register();
        // 执行一些操作
        register.unregister();
    }
}

以上代码使用Curator实现了MySQL连接节点的注册和监听，其中使用了`PersistentNode`、`NodeCache`和`PathChildrenCache`三个类实现节点的创建、读取和监听。在`register()`方法中设置了`mysqlNode`的状态监听器和`mysqlNodeCache`的数据监听器，以及`mysqlNodeChildrenCache`的子节点监听器，并在相应的回调函数中处理连接的使用和节点的删除事件。在`unregister()`方法中关闭相应的节点和客户端，以结束注册和监听。