使用JAVA编写curator监听mysql的代码

### 回答1：
以下是使用 Java 编写 Curator 监听 MySQL 的示例代码：

import org.apache.curator.framework.CuratorFramework;
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.retry.RetryNTimes;
import org.apache.zookeeper.CreateMode;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;

public class CuratorMySQLListener {
    private static final String ZK_ADDRESS = "localhost:2181";
    private static final String ZK_PATH = "/mysql/config";
    private static final String JDBC_URL = "jdbc:mysql://localhost:3306/test";
    private static final String USERNAME = "root";
    private static final String PASSWORD = "password";

    public static void main(String[] args) throws Exception {
        CuratorFramework client = CuratorFrameworkFactory.newClient(ZK_ADDRESS, new RetryNTimes(3, 1000));
        client.start();

        // 创建永久节点
        client.create().creatingParentsIfNeeded().withMode(CreateMode.PERSISTENT).forPath(ZK_PATH);

        // 监听节点变化
        PathChildrenCache cache = new PathChildrenCache(client, ZK_PATH, true);
        cache.start(PathChildrenCache.StartMode.POST_INITIALIZED_EVENT);
        cache.getListenable().addListener(new PathChildrenCacheListener() {
            @Override
            public void childEvent(CuratorFramework curatorFramework, PathChildrenCacheEvent event) throws Exception {
                String path = event.getData().getPath();
                switch (event.getType()) {
                    case CHILD_ADDED:
                        System.out.println("Node added: " + path);
                        updateConfig();
                        break;
                    case CHILD_UPDATED:
                        System.out.println("Node updated: " + path);
                        updateConfig();
                        break;
                    case CHILD_REMOVED:
                        System.out.println("Node removed: " + path);
                        break;
                    default:
                        break;
                }
            }
        });

        // 模拟配置更新
        client.setData().forPath(ZK_PATH, "mysql.user=alice\nmysql.password=123456".getBytes());

        Thread.sleep(Integer.MAX_VALUE);
    }

    private static void updateConfig() throws Exception {
        // 从 ZooKeeper 中获取配置信息
        CuratorFramework client = CuratorFrameworkFactory.newClient(ZK_ADDRESS, new RetryNTimes(3, 1000));
        client.start();
        byte[] data = client.getData().forPath(ZK_PATH);
        String config = new String(data);

        // 解析配置信息
        String[] lines = config.split("\n");
        String user = null;
        String password = null;
        for (String line : lines) {
            String[] parts = line.split("=");
            if (parts[0].equals("mysql.user")) {
                user = parts[1];
            } else if (parts[0].equals("mysql.password")) {
                password = parts[1];
            }
        }

        // 更新 MySQL 配置并执行查询
        String url = JDBC_URL + "?user=" + user + "&password=" + password;
        try (Connection conn = DriverManager.getConnection(url, USERNAME, PASSWORD);
             Statement stmt = conn.createStatement()) {
            ResultSet rs = stmt.executeQuery("SELECT * FROM users");
            while (rs.next()) {
                System.out.println(rs.getString("name"));
            }
        }
    }
}

以上代码会监听 `/mysql/config` 节点的变化，并在节点被添加、更新或删除时执行相应的操作。在本例中，当节点被添加或更新时，会从 ZooKeeper 中获取 MySQL 的用户名和密码，并使用这些信息连接 MySQL 数据库并执行一条查询语句。

### 回答2：
使用Curator监听MySQL的代码主要涉及以下几个步骤：

1. 引入相关依赖：
首先需要在pom.xml文件中引入Curator和MySQL相关的依赖。

<dependencies>
    <dependency>
        <groupId>org.apache.curator</groupId>
        <artifactId>curator-recipes</artifactId>
        <version>4.3.0</version>
    </dependency>
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>8.0.23</version>
    </dependency>
</dependencies>

2. 编写Curator监听代码：

package com.example;

import org.apache.curator.framework.CuratorFramework;
import org.apache.curator.framework.CuratorFrameworkFactory;
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.retry.ExponentialBackoffRetry;
import org.apache.curator.utils.CloseableUtils;

import java.nio.charset.StandardCharsets;

public class CuratorMySQLListener {
    private static final String ZK_ADDRESS = "127.0.0.1:2181";
    private static final String ZK_PATH = "/mysql_config"; // ZK节点路径
    private static final String DB_HOST = "localhost";
    private static final String DB_PORT = "3306";
    private static final String DB_NAME = "test";
    private static final String DB_USER = "root";
    private static final String DB_PASSWORD = "password";

    public static void main(String[] args) {
        CuratorFramework client = null;
        PathChildrenCache cache = null;
        try {
            client = CuratorFrameworkFactory.newClient(ZK_ADDRESS, new ExponentialBackoffRetry(1000, 3));
            client.start();

            cache = new PathChildrenCache(client, ZK_PATH, true);
            cache.start(PathChildrenCache.StartMode.POST_INITIALIZED_EVENT);

            cache.getListenable().addListener(new PathChildrenCacheListener() {
                @Override
                public void childEvent(CuratorFramework client, PathChildrenCacheEvent event) throws Exception {
                    switch (event.getType()) {
                        case CHILD_ADDED:
                            String config = new String(event.getData().getData(), StandardCharsets.UTF_8);
                            updateMySQLConfig(config);
                            break;
                        case CHILD_UPDATED:
                            config = new String(event.getData().getData(), StandardCharsets.UTF_8);
                            updateMySQLConfig(config);
                            break;
                        case CHILD_REMOVED:
                            // Do something when a child node is removed
                            break;
                        default:
                            break;
                    }
                }
            });

            Thread.sleep(Integer.MAX_VALUE);
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            CloseableUtils.closeQuietly(cache);
            CloseableUtils.closeQuietly(client);
        }
    }

    private static void updateMySQLConfig(String config) {
        // 解析config并更新MySQL配置
        // ...
        System.out.println("Updated MySQL config: " + config);
    }
}

3. 运行代码：
运行CuratorMySQLListener类，程序将启动Curator客户端并监听ZooKeeper节点路径，当节点发生变化时，会触发相应的事件并执行相应的操作。

以上代码是一个简单的示例，实际应用中还需根据具体需求和业务逻辑进行适当修改。