C#中关于ActiveMQ的应用详解

ActiveMQ是个好东东，不必多说。ActiveMQ提供多种语言支持，如Java, C, C++, C#, Ruby, Perl, Python, PHP等。由于我在windows下开发GUI，比较关心C++和C#，其中C#的ActiveMQ很简单，Apache提供NMS（.Net Messaging Service）支持.Net开发，只需如下几个步骤即能建立简单的实现。C++的应用相对麻烦些，稍后写文章介绍。

1、去ActiveMQ官方网站下载最新版的ActiveMQ，我之前下的是5.3.1，5.3.2现在也已经出来了。

2、去ActiveMQ官方网站下载最新版的Apache.NMS，需要下载Apache.NMS和Apache.NMS.ActiveMQ两个bin包，如果对源码感兴趣，也可下载src包。这里要提醒一下，如果下载1.2.0版本的NMS.ActiveMQ，Apache.NMS.ActiveMQ.dll在实际使用中有个bug，即停止ActiveMQ应用时会抛WaitOne函数异常，查看src包中的源码发现是由于Apache.NMS.ActiveMQ-1.2.0-src\src\main\csharp\Transport\InactivityMonitor.cs中的如下代码造成的，修改一下源码重新编译即可。看了一下最新版1.3.0已经修复了这个bug，因此下载最新版即可。

private void StopMonitorThreads()             {                 lock(monitor)                 {                     if(monitorStarted.CompareAndSet(true, false))                     {                         AutoResetEvent shutdownEvent = new AutoResetEvent(false);                         // Attempt to wait for the Timers to shutdown, but don't wait                         // forever, if they don't shutdown after two seconds, just quit.                         this.readCheckTimer.Dispose(shutdownEvent);                         shutdownEvent.WaitOne(TimeSpan.FromMilliseconds(2000));                         this.writeCheckTimer.Dispose(shutdownEvent);                         shutdownEvent.WaitOne(TimeSpan.FromMilliseconds(2000));                                                         //WaitOne的定义：public virtual bool WaitOne(TimeSpan timeout,bool exitContext)                         this.asyncTasks.Shutdown();                         this.asyncTasks = null;                         this.asyncWriteTask = null;                         this.asyncErrorTask = null;                     }                 }             }    　　　　 private void StopMonitorThreads()           {               lock(monitor)               {                   if(monitorStarted.CompareAndSet(true, false))                   {                       AutoResetEvent shutdownEvent = new AutoResetEvent(false);                        // Attempt to wait for the Timers to shutdown, but don't wait                       // forever, if they don't shutdown after two seconds, just quit.                       this.readCheckTimer.Dispose(shutdownEvent);                       shutdownEvent.WaitOne(TimeSpan.FromMilliseconds(2000));                       this.writeCheckTimer.Dispose(shutdownEvent);                       shutdownEvent.WaitOne(TimeSpan.FromMilliseconds(2000));                                                       //WaitOne的定义：public virtual bool WaitOne(TimeSpan timeout,bool exitContext)                       this.asyncTasks.Shutdown();                       this.asyncTasks = null;                       this.asyncWriteTask = null;                       this.asyncErrorTask = null;                   }               }           }

3、运行ActiveMQ，找到ActiveMQ解压后的bin文件夹：...\apache-activemq-5.3.1\bin，执行activemq.bat批处理文件即可启动ActiveMQ服务器，默认端口为61616，这可在配置文件中修改。

4、写C#程序实现ActiveMQ的简单应用。新建C#工程（一个Producter项目和一个Consumer项目），WinForm或Console程序均可，这里建的是Console工程，添加对Apache.NMS.dll和Apache.NMS.ActiveMQ.dll的引用，然后即可编写实现代码了，简单的Producer和Consumer实现代码如下：

producer：

using System;     using System.Collections.Generic;     using System.Text;     using Apache.NMS;     using Apache.NMS.ActiveMQ;     using System.IO;     using System.Xml.Serialization;     using System.Runtime.Serialization.Formatters.Binary;     namespace Publish     {         class Program         {             static void Main(string[] args)             {                 try                {                     //Create the Connection Factory                     IConnectionFactory factory = new ConnectionFactory("tcp://localhost:61616/");                     using (IConnection connection = factory.CreateConnection())                     {                         //Create the Session                         using (ISession session = connection.CreateSession())                         {                             //Create the Producer for the topic/queue                             IMessageProducer prod = session.CreateProducer(                                 new Apache.NMS.ActiveMQ.Commands.ActiveMQTopic("testing"));                             //Send Messages                             int i = 0;                             while (!Console.KeyAvailable)                             {                                 ITextMessage msg = prod.CreateTextMessage();                                 msg.Text = i.ToString();                                 Console.WriteLine("Sending: " + i.ToString());                                 prod.Send(msg, Apache.NMS.MsgDeliveryMode.NonPersistent, Apache.NMS.MsgPriority.Normal, TimeSpan.MinValue);                                 System.Threading.Thread.Sleep(5000);                                 i++;                             }                         }                     }                     Console.ReadLine();                }                 catch (System.Exception e)                 {                     Console.WriteLine("{0}",e.Message);                     Console.ReadLine();                 }             }         }     }

consumer:

using System;     using System.Collections.Generic;     using System.Text;     using Apache.NMS;     using Apache.NMS.ActiveMQ;     using System.IO;     using System.Xml.Serialization;     using System.Runtime.Serialization.Formatters.Binary;     namespace Subscribe     {         class Program         {             static void Main(string[] args)             {                 try                {                     //Create the Connection factory                     IConnectionFactory factory = new ConnectionFactory("tcp://localhost:61616/");                     //Create the connection                     using (IConnection connection = factory.CreateConnection())                     {                         connection.ClientId = "testing listener";                         connection.Start();                         //Create the Session                         using (ISession session = connection.CreateSession())                         {                             //Create the Consumer                             IMessageConsumer consumer = session.CreateDurableConsumer(new Apache.NMS.ActiveMQ.Commands.ActiveMQTopic("testing"), "testing listener", null, false);                             consumer.Listener += new MessageListener(consumer_Listener);                             Console.ReadLine();                         }                         connection.Stop();                         connection.Close();                     }                 }                 catch (System.Exception e)                 {                     Console.WriteLine(e.Message);                 }             }             static void consumer_Listener(IMessage message)             {                 try                {                     ITextMessage msg = (ITextMessage)message;                     Console.WriteLine("Receive: " + msg.Text);                }                 catch (System.Exception e)                 {                     Console.WriteLine(e.Message);                 }             }         }     }

编译生成producer.exe和consumer.exe，并执行两个exe，即可看到消息的发送与接收了。

这个例子是建的主题（Topic），ActiveMQ还支持另一种方式：Queue，即P2P，两者有什么区别呢？区别在于，Topic是广播，即如果某个Topic被多个消费者订阅，那么只要有消息到达服务器，服务器就将该消息发给全部的消费者；而Queue是点到点，即一个消息只能发给一个消费者，如果某个Queue被多个消费者订阅，没有特殊情况的话消息会一个一个地轮流发给不同的消费者，比如：

msg1-->consumer A

msg2-->consumer B

msg3-->consumer C

msg4-->consumer A

msg5-->consumer B

msg6-->consumer C

特殊情况是指：ActiveMQ支持过滤机制，即生产者可以设置消息的属性（Properties），该属性与消费者端的Selector对应，只有消费者设置的selector与消息的Properties匹配，消息才会发给该消费者。Topic和Queue都支持Selector。

Properties和Selector该如何设置呢？请看如下代码：

producer：

public void SetProperties()  {  ITextMessage msg = prod.CreateTextMessage();                                 msg.Text = i.ToString();                                 msg.Properties.SetString("myFilter", "test1");                                 Console.WriteLine("Sending: " + i.ToString());                                 prod.Send(msg, Apache.NMS.MsgDeliveryMode.NonPersistent, Apache.NMS.MsgPriority.Normal, TimeSpan.MinValue);    ITextMessage msg = prod.CreateTextMessage();                               msg.Text = i.ToString();                               msg.Properties.SetString("myFilter", "test1");                               Console.WriteLine("Sending: " + i.ToString());                               prod.Send(msg, Apache.NMS.MsgDeliveryMode.NonPersistent, Apache.NMS.MsgPriority.Normal, TimeSpan.MinValue);    }

consumer：

public void SetSelector()  {  //生成consumer时通过参数设置Selector     IMessageConsumer consumer = session.CreateConsumer(new Apache.NMS.ActiveMQ.Commands.ActiveMQQueue("testing"), "myFilter='test1'");    //生成consumer时通过参数设置Selector   IMessageConsumer consumer = session.CreateConsumer(new Apache.NMS.ActiveMQ.Commands.ActiveMQQueue("testing"), "myFilter='test1'");  }

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