RabbitMQ RFC同步调用是使用了两个异步调用完成的，生产者调用消费者的同时，自己也作为消费者等待某一队列的返回消息，消费者接受到生产者的消息同时，也作为消息发送者发送一消息给生产者。参考下图：
调用流程如下：
其他的消息服务器实现同步调用也是类似的原理，比如ActiveMQ。
下面编写消费者类Server
生产者Client代码
启动一命令行，将当前目录转移到项目所在的目录
在Eclipse中运行Client
代码：
package com.test.rfc;
import java.io.IOException;
import com.rabbitmq.client.AMQP;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import com.rabbitmq.client.ConnectionFactory;
import com.rabbitmq.client.Consumer;
import com.rabbitmq.client.DefaultConsumer;
import com.rabbitmq.client.Envelope;
public class Server {
public static void main(String[] argv) {
ConnectionFactory factory = new ConnectionFactory();
factory.setUsername("admin");
factory.setPassword("admin");
factory.setHost("192.168.169.142");
//使用默认端口5672
Connection connection = null;
try {
connection = factory.newConnection();
final Channel channel = connection.createChannel();
String queueName = "queue_rpc";
channel.queueDeclare(queueName, false, false, false,
null);
Consumer consumer = new DefaultConsumer(channel) {
@Override
public void handleDelivery(String consumerTag,
Envelope envelope, AMQP.BasicProperties properties,
byte[] body) throws IOException
{
System.out.println("test1" + new String(body));
AMQP.BasicProperties replyProps = new
AMQP.BasicProperties.Builder()
.correlationId(properties.getCorrelationId())
.build();
String response = "hello client,I‘m rfc server";
channel.basicPublish("", properties.getReplyTo(),
replyProps, response.getBytes());
channel.basicAck(envelope.getDeliveryTag(), false);
}
};
channel.basicConsume(queueName, false, consumer);
} catch (IOException e) {
e.printStackTrace();
}
}
}
package com.test.rfc;
import java.io.IOException;
import java.util.UUID;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
import com.rabbitmq.client.*;
public class Client {
public static void main(String[] argv) {
try
{
//发送消息的队列,Server在这个队列上接受消息
String queueName = "queue_rpc";
ConnectionFactory factory = new ConnectionFactory();
factory.setUsername("admin");
factory.setPassword("admin");
factory.setHost("192.168.169.142");
//使用默认端口5672
Connection connection = null;
connection = factory.newConnection();
Channel channel = connection.createChannel();
//生成临时的队列,Client在这队列上等待Server返回信息,Server向这个队列发消息
String replyQueueName =
channel.queueDeclare().getQueue();
//生成唯一ID
final String corrId = UUID.randomUUID().toString();
AMQP.BasicProperties props = new
AMQP.BasicProperties.Builder()
.correlationId(corrId).replyTo(replyQueueName).build();
//客户端发送RFC请求
channel.basicPublish("", queueName, props,
"GetUserInfo".getBytes());
//Server返回消息
final BlockingQueue response = new
ArrayBlockingQueue(1);
channel.basicConsume(replyQueueName, true,
new DefaultConsumer(channel) {
@Override
public void handleDelivery(String consumerTag,
Envelope envelope, AMQP.BasicProperties properties,
byte[] body) throws IOException {
System.out.println(properties.getCorrelationId());
if (properties.getCorrelationId().equals(corrId)) {
response.offer(body);
}
}
});
byte[] b = response.take();
System.out.println(new String(b));
channel.close();
connection.close();
}
catch(Exception e)
{
e.printStackTrace();
}
}
}