RabbitMQ RPC 通信模式详解

常量类

public class Constants {
    public static final String HOST = "localhost"; // 请根据实际情况修改
    public static final int PORT = 5672;
    public static final String USER_NAME = "guest"; // 请根据实际情况修改
    public static final String PASSWORD = "guest"; // 请根据实际情况修改
    public static final String VIRTUAL_HOST = "/";
    // rpc 模式
    public static final String RPC_REQUEST_QUEUE = "rpc.request.queue";
    public static final String RPC_RESPONSE_QUEUE = "rpc.response.queue";
}

编写客户端代码

import com.rabbitmq.client.*;
import rabbitmq.constant.Constants;
import java.io.IOException;
import java.util.UUID;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.TimeoutException;

/**
 * rpc 客户端
 * 1. 发送请求
 * 2. 接收响应
 */
public class RpcClient {
    public static void main(String[] args) throws IOException, TimeoutException, InterruptedException {
        // 1. 建立连接
        ConnectionFactory connectionFactory = new ConnectionFactory();
        connectionFactory.setHost(Constants.HOST);
        connectionFactory.setPort(Constants.PORT);
        connectionFactory.setUsername(Constants.USER_NAME);
        connectionFactory.setPassword(Constants.PASSWORD);
        connectionFactory.setVirtualHost(Constants.VIRTUAL_HOST);
        Connection connection = connectionFactory.newConnection();

        // 2. 开启信道
        Channel channel = connection.createChannel();
        channel.queueDeclare(Constants.RPC_REQUEST_QUEUE, true, false, false, null);
        channel.queueDeclare(Constants.RPC_RESPONSE_QUEUE, true, false, false, null);

        // 3. 发送请求
        String msg = "hello rpc...";
        // 设置请求的唯一标识
        String correlationID = UUID.randomUUID().toString();
        // 设置请求的相关属性
        AMQP.BasicProperties props = new AMQP.BasicProperties.Builder()
                .correlationId(correlationID)
                .replyTo(Constants.RPC_RESPONSE_QUEUE)
                .build();
        channel.basicPublish("", Constants.RPC_REQUEST_QUEUE, props, msg.getBytes());

        // 4. 接收响应
        // 使用阻塞队列，来存储响应信息
        final BlockingQueue<String> response = new ArrayBlockingQueue<>(1);
        DefaultConsumer consumer = new DefaultConsumer(channel) {
            @Override
            public void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties, byte[] body) throws IOException {
                String respMsg = new String(body);
                System.out.println("接收到回调消息：" + respMsg);
                if (correlationID.equals(properties.getCorrelationId())) {
                    // 如果 correlationID 校验一致
                    response.offer(respMsg);
                }
            }
        };
        channel.basicConsume(Constants.RPC_RESPONSE_QUEUE, true, consumer);
        String result = response.take();
        System.out.println("[RPC Client 响应结果]:" + result);
    }
}

编写服务端代码

import com.rabbitmq.client.*;
import rabbitmq.constant.Constants;
import java.io.IOException;
import java.util.concurrent.TimeoutException;

/**
 * RPC server
 * 1. 接收请求
 * 2. 发送响应
 */
public class RpcServer {
    public static void main(String[] args) throws IOException, TimeoutException {
        // 1. 建立连接
        ConnectionFactory connectionFactory = new ConnectionFactory();
        connectionFactory.setHost(Constants.HOST);
        connectionFactory.setPort(Constants.PORT);
        connectionFactory.setUsername(Constants.USER_NAME);
        connectionFactory.setPassword(Constants.PASSWORD);
        connectionFactory.setVirtualHost(Constants.VIRTUAL_HOST);
        Connection connection = connectionFactory.newConnection();

        // 2. 开启信道
        Channel channel = connection.createChannel();

        // 3. 接收请求
        channel.basicQos(1);
        DefaultConsumer consumer = new DefaultConsumer(channel) {
            @Override
            public void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties, byte[] body) throws IOException {
                String request = new String(body, "UTF-8");
                System.out.println("接收到请求:" + request);
                String response = "针对 request:" + request + ", 响应成功";
                AMQP.BasicProperties basicProperties = new AMQP.BasicProperties.Builder()
                        .correlationId(properties.getCorrelationId())
                        .build();
                channel.basicPublish("", Constants.RPC_RESPONSE_QUEUE, basicProperties, response.getBytes());
                channel.basicAck(envelope.getDeliveryTag(), false);
            }
        };
        channel.basicConsume(Constants.RPC_REQUEST_QUEUE, false, consumer);
    }
}

运行说明

先运行客户端，再运行服务端。可以在管理界面看到其中一个队列中有 1 条消息。

我们可以看到，服务端接收到了消息并给客户端发送了响应，与预期符合。