如何使得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，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。

Curator提供了一个名为ConnectionStateManager的接口，它可以用于管理连接状态。我们可以使用它来实现在Curator注册的MySQL连接节点中存储实际的连接对象或连接状态。

以下是一个基本的实现代码：

import org.apache.curator.framework.CuratorFramework;
import org.apache.curator.framework.recipes.cache.ChildData;
import org.apache.curator.framework.recipes.cache.NodeCache;
import org.apache.curator.framework.recipes.cache.NodeCacheListener;
import org.apache.curator.framework.recipes.nodes.PersistentNode;
import org.apache.curator.framework.state.ConnectionState;
import org.apache.curator.framework.state.ConnectionStateListener;

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

public class MySQLConnectionStateManager implements ConnectionStateListener, NodeCacheListener {
    private final CuratorFramework curatorFramework;
    private final String nodePath;
    private final String connectionString;
    private final String username;
    private final String password;
    private final NodeCache nodeCache;
    private Connection connection;

    public MySQLConnectionStateManager(CuratorFramework curatorFramework, String nodePath, String connectionString, String username, String password) {
        this.curatorFramework = curatorFramework;
        this.nodePath = nodePath;
        this.connectionString = connectionString;
        this.username = username;
        this.password = password;
        this.nodeCache = new NodeCache(curatorFramework, nodePath);
    }

    public void start() throws Exception {
        // 创建持久节点
        PersistentNode persistentNode = new PersistentNode(curatorFramework, PersistentNode.Mode.EPHEMERAL, nodePath);
        persistentNode.start();

        // 添加连接状态监听器
        curatorFramework.getConnectionStateListenable().addListener(this);

        // 添加节点数据监听器
        nodeCache.getListenable().addListener(this);

        // 启动节点数据监听器
        nodeCache.start();

        // 初始化连接
        connection = createConnection(nodeCache.getCurrentData());
    }

    public void close() throws IOException {
        if (connection != null) {
            try {
                connection.close();
            } catch (SQLException e) {
                // 处理关闭连接时发生的异常
            }
        }
        nodeCache.close();
    }

    private Connection createConnection(ChildData childData) throws SQLException {
        if (childData == null) {
            return null;
        }
        String connectionString = new String(childData.getData());
        return DriverManager.getConnection(connectionString, username, password);
    }

    @Override
    public void stateChanged(CuratorFramework client, ConnectionState newState) {
        switch (newState) {
            case CONNECTED:
            case RECONNECTED:
                try {
                    // 连接恢复，重新创建连接对象
                    connection = createConnection(nodeCache.getCurrentData());
                } catch (SQLException e) {
                    // 处理连接创建时发生的异常
                }
                break;
            case SUSPENDED:
            case LOST:
                // 连接中断或丢失，关闭连接对象
                if (connection != null) {
                    try {
                        connection.close();
                    } catch (SQLException e) {
                        // 处理关闭连接时发生的异常
                    }
                    connection = null;
                }
                break;
            default:
                break;
        }
    }

    @Override
    public void nodeChanged() throws Exception {
        // 节点数据变化，重新创建连接对象
        connection = createConnection(nodeCache.getCurrentData());
    }
}

使用示例：

CuratorFramework curatorFramework = ...; // 创建CuratorFramework实例
String nodePath = "/mysql/connection"; // MySQL连接节点路径
String connectionString = "jdbc:mysql://localhost:3306/mydb"; // MySQL连接字符串
String username = "root"; // MySQL用户名
String password = "password"; // MySQL密码

MySQLConnectionStateManager connectionStateManager = new MySQLConnectionStateManager(curatorFramework, nodePath, connectionString, username, password);
connectionStateManager.start(); // 启动连接状态管理器

// ...使用连接对象进行数据库操作

connectionStateManager.close(); // 关闭连接状态管理器