Java Flink 使用连接池发送 RabbitMQ 消息

要在 Java Flink 中使用连接池发送 RabbitMQ 消息，可以按照以下步骤进行操作：

首先，需要添加 RabbitMQ 客户端库的依赖项到您的 Flink 项目中。您可以在'pom.xml'文件中添加以下依赖项：

<dependency>
    <groupId>com.rabbitmq</groupId>
    <artifactId>amqp-client</artifactId>
    <version>版本号</version>
</dependency>

创建一个 RabbitMQ 连接池，可以使用任何支持连接池的库，例如'Apache Commons Pool'。创建连接池的示例代码如下所示：

GenericObjectPoolConfig<RabbitMQConnection> config = new GenericObjectPoolConfig<>();
config.setMaxTotal(10);
config.setMaxIdle(5);
config.setMinIdle(1);
config.setTestOnBorrow(true);

PoolableObjectFactory<RabbitMQConnection> factory = new BaseKeyedPooledObjectFactory<String, RabbitMQConnection>() {
    @Override
    public RabbitMQConnection create(String key) throws Exception {
        // 创建 RabbitMQ 连接
        return new RabbitMQConnection(key);
    }

    @Override
    public PooledObject<RabbitMQConnection> wrap(RabbitMQConnection value) {
        return new DefaultPooledObject<>(value);
    }

    @Override
    public void destroyObject(String key, PooledObject<RabbitMQConnection> p) throws Exception {
        // 销毁 RabbitMQ 连接
        p.getObject().close();
    }
};

KeyedObjectPool<String, RabbitMQConnection> pool = new GenericKeyedObjectPool<>(factory, config);

创建一个包装类'RabbitMQConnection'来管理 RabbitMQ 连接。在该类中，可以在构造函数中创建和关闭 RabbitMQ 连接，并提供一个'send'方法来发送消息。示例代码如下所示：

public class RabbitMQConnection {
    private Connection connection;
    private Channel channel;

    public RabbitMQConnection(String key) throws IOException, TimeoutException {
        ConnectionFactory factory = new ConnectionFactory();
        factory.setHost("localhost");
        factory.setPort(5672);
        factory.setUsername("guest");
        factory.setPassword("guest");

        connection = factory.newConnection();
        channel = connection.createChannel();
        channel.queueDeclare(key, false, false, false, null);
    }

    public void send(String key, String message) throws IOException {
        channel.basicPublish("", key, null, message.getBytes());
    }

    public void close() throws IOException, TimeoutException {
        channel.close();
        connection.close();
    }
}

在 Flink 作业中使用连接池来发送 RabbitMQ 消息。您可以使用'RichAsyncFunction'或'RichSinkFunction'接口来实现。以下是一个使用'RichAsyncFunction'接口的示例代码：

public class RabbitMQAsyncFunction extends RichAsyncFunction<String, String> {
    private transient KeyedObjectPool<String, RabbitMQConnection> pool;

    @Override
    public void open(Configuration parameters) throws Exception {
        GenericObjectPoolConfig<RabbitMQConnection> config = new GenericObjectPoolConfig<>();
        config.setMaxTotal(10);
        config.setMaxIdle(5);
        config.setMinIdle(1);
        config.setTestOnBorrow(true);

        PoolableObjectFactory<RabbitMQConnection> factory = new BaseKeyedPooledObjectFactory<String, RabbitMQConnection>() {
            @Override
            public RabbitMQConnection create(String key) throws Exception {
                // 创建 RabbitMQ 连接
                return new RabbitMQConnection(key);
            }

            @Override
            public PooledObject<RabbitMQConnection> wrap(RabbitMQConnection value) {
                return new DefaultPooledObject<>(value);
            }

            @Override
            public void destroyObject(String key, PooledObject<RabbitMQConnection> p) throws Exception {
                // 销毁 RabbitMQ 连接
                p.getObject().close();
            }
        };

        pool = new GenericKeyedObjectPool<>(factory, config);
    }

    @Override
    public void asyncInvoke(String input, ResultFuture<String> resultFuture) throws Exception {
        String key = "your_routing_key";  // 设置消息的路由键
        String message = input;  // 准备要发送的消息

        RabbitMQConnection connection = pool.borrowObject(key);
        connection.send(key, message);
        pool.returnObject(key, connection);

        resultFuture.complete(Collections.singleton("Message sent to RabbitMQ"));
    }

    @Override
    public void close() throws Exception {
        pool.close();
    }
}

请根据您的实际情况调整代码中的连接参数和路由键。这只是一个示例，您可以根据自己的需求进行修改。