.NetCore利用BlockingCollection实现简易消息队列

消息队列现今的应用场景越来越大，常用的有RabbmitMQ和KafKa。

我们用BlockingCollection来实现简单的消息队列。

BlockingCollection实现了生产者/消费者模式，是对IProducerConsumerCollection<T>接口的实现。与其他Concurrent集合一样，每次Add或Take元素，都会导致对集合的lock。只有当确定需要在内存中创建一个生产者，消费者模式时，再考虑这个类。

MSDN中的示例用法：

using (BlockingCollection<int> bc = new BlockingCollection<int>())  {    Task.Factory.StartNew(() =>    {      for (int i = 0; i < 1000; i++)      {        bc.Add(i);        Thread.Sleep(50);       }        // Need to do this to keep foreach below from hanging      bc.CompleteAdding();    });      // Now consume the blocking collection with foreach.    // Use bc.GetConsumingEnumerable() instead of just bc because the    // former will block waiting for completion and the latter will    // simply take a snapshot of the current state of the underlying collection.    foreach (var item in bc.GetConsumingEnumerable())    {      Console.WriteLine(item);    }  }

实现消息队列

用Vs2017创建一个控制台应用程序。创建DemoQueueBlock类，封装一些常用判断。

HasEle,判断是否有元素
Add向队列中添加元素
Take从队列中取出元素

为了不把BlockingCollection直接暴漏给使用者，我们封装一个DemoQueueBlock类

  /// <summary>  /// BlockingCollection演示消息队列  /// </summary>  /// <typeparam name="T"></typeparam>  public class DemoQueueBlock<T> where T : class  {    private static BlockingCollection<T> Colls;    public DemoQueueBlock()    {    }    public static bool IsComleted() {      if (Colls != null && Colls.IsCompleted) {        return true;      }      return false;    }    public static bool HasEle()    {      if (Colls != null && Colls.Count>0)      {        return true;      }      return false;    }        public static bool Add(T msg)    {      if (Colls == null)      {        Colls = new BlockingCollection<T>();      }      Colls.Add(msg);      return true;    }    public static T Take()    {      if (Colls == null)      {        Colls = new BlockingCollection<T>();      }      return Colls.Take();    }  }  /// <summary>  /// 消息体  /// </summary>  public class DemoMessage  {    public string BusinessType { get; set; }    public string BusinessId { get; set; }    public string Body { get; set; }  }

添加元素进队列

通过控制台，添加元素

      //添加元素      while (true)      {        Console.WriteLine("请输入队列");        var read = Console.ReadLine();        if (read == "exit")        {          return;        }        DemoQueueBlock<DemoMessage>.Add(new DemoMessage() { BusinessId = read });      }

消费队列

通过判断IsComleted，来确定是否获取队列

 Task.Factory.StartNew(() =>      {        //从队列中取元素。        while (!DemoQueueBlock<DemoMessage>.IsComleted())        {          try          {            var m = DemoQueueBlock<DemoMessage>.Take();           Console.WriteLine("已消费:" + m.BusinessId);          }          catch (Exception ex)          {            Console.WriteLine(ex.Message);          }        }      });

查看运行结果