Question

我是RabbitMQ的新手。我希望能够在有多个队列（要读取）的情况下处理读取消息而不会阻塞。有关如何做到这一点的任何意见？

//编辑1

public class Rabbit : IMessageBus
{   

    private List<string> publishQ = new List<string>();
    private List<string> subscribeQ = new List<string>();

    ConnectionFactory factory = null;
    IConnection connection = null;
    IModel channel = null;  
    Subscription sub = null;

    public void writeMessage( Measurement m1 ) {
        byte[] body = Measurement.AltSerialize( m1 );
        int msgCount = 1;
        Console.WriteLine("Sending message to queue {1} via the amq.direct exchange.", m1.id);

        string finalQueue = publishToQueue( m1.id );

        while (msgCount --> 0) {
            channel.BasicPublish("amq.direct", finalQueue, null, body);
        }

        Console.WriteLine("Done. Wrote the message to queue {0}.\n", m1.id);
    }

     public string publishToQueue(string firstQueueName) {
        Console.WriteLine("Creating a queue and binding it to amq.direct");
        string queueName = channel.QueueDeclare(firstQueueName, true, false, false, null);
        channel.QueueBind(queueName, "amq.direct", queueName, null);
        Console.WriteLine("Done.  Created queue {0} and bound it to amq.direct.\n", queueName);
        return queueName;
    }


    public Measurement readMessage() {
        Console.WriteLine("Receiving message...");
        Measurement m = new Measurement();

        int i = 0;
        foreach (BasicDeliverEventArgs ev in sub) {
            m = Measurement.AltDeSerialize(ev.Body);
            //m.id = //get the id here, from sub
            if (++i == 1)
                break;
            sub.Ack();
        }

        Console.WriteLine("Done.\n");
        return m;
    }


    public void subscribeToQueue(string queueName ) 
    {
        sub = new Subscription(channel, queueName);
    }

    public static string MsgSysName;
    public string MsgSys
    {
        get 
        { 
            return MsgSysName;
        }
        set
        {
            MsgSysName = value;
        }
    }

    public Rabbit(string _msgSys) //Constructor
    {   
        factory = new ConnectionFactory();
        factory.HostName = "localhost"; 
        connection = factory.CreateConnection();
        channel = connection.CreateModel();
        //consumer = new QueueingBasicConsumer(channel);

        System.Console.WriteLine("\nMsgSys: RabbitMQ");
        MsgSys = _msgSys;
    }

    ~Rabbit()
    {
        //observer??
        connection.Dispose();
        //channel.Dispose();
        System.Console.WriteLine("\nDestroying RABBIT");
    }   
}

//编辑2

private List<Subscription> subscriptions = new List<Subscription>();
    Subscription sub = null;

public Measurement readMessage()
    {
        Measurement m = new Measurement();
        foreach(Subscription element in subscriptions)
        {
            foreach (BasicDeliverEventArgs ev in element) {
                //ev = element.Next();
                if( ev != null) {
                    m = Measurement.AltDeSerialize( ev.Body );
                    return m;
                }
                m =  null;  
            }           
        }   
        System.Console.WriteLine("No message in the queue(s) at this time.");
        return m;
    }

    public void subscribeToQueue(string queueName) 
    {   
        sub = new Subscription(channel, queueName);
        subscriptions.Add(sub);     
    }

//编辑3

//MessageHandler.cs

public class MessageHandler
{   
    // Implementation of methods for Rabbit class go here
    private List<string> publishQ = new List<string>();
    private List<string> subscribeQ = new List<string>();

    ConnectionFactory factory = null;
    IConnection connection = null;
    IModel channel = null;  
    QueueingBasicConsumer consumer = null;  

    private List<Subscription> subscriptions = new List<Subscription>();
    Subscription sub = null;

    public void writeMessage ( Measurement m1 )
    {
        byte[] body = Measurement.AltSerialize( m1 );
        //declare a queue if it doesn't exist
        publishToQueue(m1.id);

        channel.BasicPublish("amq.direct", m1.id, null, body);
        Console.WriteLine("\n  [x] Sent to queue {0}.", m1.id);
    }

    public void publishToQueue(string queueName)
    {   
        string finalQueueName = channel.QueueDeclare(queueName, true, false, false, null);
        channel.QueueBind(finalQueueName, "amq.direct", "", null);
    }

    public Measurement readMessage()
    {
        Measurement m = new Measurement();
        foreach(Subscription element in subscriptions)
        {
            if( element.QueueName == null)
            {
                m = null;
            }
            else 
            {
                BasicDeliverEventArgs ev = element.Next();
                if( ev != null) {
                    m = Measurement.AltDeSerialize( ev.Body );
                    m.id = element.QueueName;
                    element.Ack();
                    return m;
                }
                m =  null;                      
            }
            element.Ack();
        }   
        System.Console.WriteLine("No message in the queue(s) at this time.");
        return m;
    }

    public void subscribeToQueue(string queueName) 
    {   
        sub = new Subscription(channel, queueName);
        subscriptions.Add(sub); 
    }

    public static string MsgSysName;
    public string MsgSys
    {
        get 
        { 
            return MsgSysName;
        }
        set
        {
            MsgSysName = value;
        }
    }

    public MessageHandler(string _msgSys) //Constructor
    {   
        factory = new ConnectionFactory();
        factory.HostName = "localhost"; 
        connection = factory.CreateConnection();
        channel = connection.CreateModel();
        consumer = new QueueingBasicConsumer(channel);

        System.Console.WriteLine("\nMsgSys: RabbitMQ");
        MsgSys = _msgSys;
    }

    public void disposeAll()
    {
        connection.Dispose();
        channel.Dispose();
        foreach(Subscription element in subscriptions)
        {
            element.Close();
        }
        System.Console.WriteLine("\nDestroying RABBIT");
    }   
}

// App1.cs

using System;
using System.IO;

using UtilityMeasurement;
using UtilityMessageBus;


public class MainClass
{
    public static void Main()
    {

    MessageHandler obj1 = MessageHandler("Rabbit");

    System.Console.WriteLine("\nA {0} object is now created.", MsgSysName);

    //Create new Measurement messages
    Measurement m1 = new Measurement("q1", 2345, 23.456); 
    Measurement m2 = new Measurement("q2", 222, 33.33);

    System.Console.WriteLine("Test message 1:\n    ID: {0}", m1.id);
    System.Console.WriteLine("    Time: {0}", m1.time);
    System.Console.WriteLine("    Value: {0}", m1.value);

    System.Console.WriteLine("Test message 2:\n    ID: {0}", m2.id);
    System.Console.WriteLine("    Time: {0}", m2.time);
    System.Console.WriteLine("    Value: {0}", m2.value);   

    // Ask queue name and store it
    System.Console.WriteLine("\nName of queue to publish to: ");
    string queueName = (System.Console.ReadLine()).ToString();
    obj1.publishToQueue( queueName );

    // Write message to the queue
    obj1.writeMessage( m1 );    

    System.Console.WriteLine("\nName of queue to publish to: ");
    string queueName2 = (System.Console.ReadLine()).ToString();
    obj1.publishToQueue( queueName2 );

    obj1.writeMessage( m2 );

    obj1.disposeAll();
}
}

// App2.cs

using System;
using System.IO;

using UtilityMeasurement;
using UtilityMessageBus;

public class MainClass
{
    public static void Main()
    {
    //Asks for the message system
    System.Console.WriteLine("\nEnter name of messageing system: ");
    System.Console.WriteLine("Usage: [Rabbit] [Zmq]");
    string MsgSysName = (System.Console.ReadLine()).ToString();

    //Declare an IMessageBus instance:
    //Here, an object of the corresponding Message System
        // (ex. Rabbit, Zmq, etc) is instantiated
    IMessageBus obj1 = MessageBusFactory.GetMessageBus(MsgSysName);

    System.Console.WriteLine("\nA {0} object is now created.", MsgSysName);

    //Create a new Measurement object m
    Measurement m = new Measurement();  

    System.Console.WriteLine("Queue name to subscribe to: ");
    string QueueName1 = (System.Console.ReadLine()).ToString();
    obj1.subscribeToQueue( QueueName1 );

    //Read message into m
    m = obj1.readMessage();

    if (m != null ) {
        System.Console.WriteLine("\nMessage received from queue {0}:\n    ID: {1}", m.id, m.id);
        System.Console.WriteLine("    Time: {0}", m.time);
        System.Console.WriteLine("    Value: {0}", m.value);
    }

    System.Console.WriteLine("Another queue name to subscribe to: ");
    string QueueName2 = (System.Console.ReadLine()).ToString();
    obj1.subscribeToQueue( QueueName2 );

    m = obj1.readMessage();

    if (m != null ) {
        System.Console.WriteLine("\nMessage received from queue {0}:\n    ID: {1}", m.id, m.id);
        System.Console.WriteLine("    Time: {0}", m.time);
        System.Console.WriteLine("    Value: {0}", m.value);
    }

    obj1.disposeAll();
}
}

Answer 1

最简单的方法是使用EventingBasicConsumer。我在我的网站上有一个如何使用它的例子。 RabbitMQ EventingBasicConsumer

此Consumer类公开您可以使用的已接收事件，因此不会阻止。其余代码基本保持不变。

从多个队列中读取，RabbitMQ

2 个答案: