Question

下面是我的代码，首先是我提出事件的地方，第二部分是我在另一个类中使用它的地方。它看起来很简单，但是日志显示即使事件被提升一次，事件也会在消耗此事件的类上触发20次以上。有什么想法吗？

IBSerialPort上课：

public delegate void PacketReceivedHandler(object sender, PacketReceivedEventArgs e);
public event PacketReceivedHandler OnPacketReceived;

public class PacketReceivedEventArgs : EventArgs
{
  public Packet PacketReceived { get; private set; }

  public PacketReceivedEventArgs(Packet packet)
  {
    PacketReceived = packet;
  }
}

// raise event
if (OnPacketReceived != null)
{
    Log("This is only called ONCE!");
    PacketReceivedEventArgs args = new PacketReceivedEventArgs(data);
    OnPacketReceived(this, args);
}

使用IBSerialPort并使用其OnPacketReceived事件的类：

IBSerialPort ibSerialPort = null;
..
if (ibSerialPort == null)
{
  Log("This is only called once");

  ibSerialPort = IBSerialPort.Instance;

  ibSerialPort.OnPacketReceived += ibSerialPort_OnPacketReceived;
}

void ibSerialPort_OnPacketReceived(object sender, IBSerialPort.PacketReceivedEventArgs args)
{
   Log("This is called ~25 times!!!!");
}

Answer 1

试试这个，这将取消注册任何普通用户：

ibSerialPort.OnPacketReceived -= ibSerialPort_OnPacketReceived;   // unregister
ibSerialPort.OnPacketReceived += ibSerialPort_OnPacketReceived;  //register

Answer 2

这被召唤多少次？如果多次调用此函数，则会多次调用您的事件。

 ibSerialPort.OnPacketReceived += ibSerialPort_OnPacketReceived;

作为测试，您可以在添加代理之前删除该代理：

ibSerialPort.OnPacketReceived -= ibSerialPort_OnPacketReceived;
ibSerialPort.OnPacketReceived += ibSerialPort_OnPacketReceived;

Answer 3

我想知道你定义ibSerialPort_OnPacketReceived的类是否被使用（即使在分开的实例中）25次，你认为你正在释放它。请考虑以下代码：

class EventSender
{
    public Action MyEvent;
}

class Subscriber
{
    public void OnEvent()
    {
        Console.WriteLine("OnEvent");
    }
}

class Program
{
    static void Main(string[] args)
    {
        EventSender es = new EventSender();

        Subscriber s = new Subscriber();
        es.MyEvent += s.OnEvent;

        s = new Subscriber();
        es.MyEvent += s.OnEvent;

        es.MyEvent();

        Console.ReadKey();
    }
}

在这里，＆＃34; OnEvent＆＃34;将被打印两次。即使看起来我已经发布了它的句柄，也会保留对订阅的引用。这是由于代表们如何保留其订阅者列表。

如果这是问题，您每次都需要取消订阅：

es.MyEvent -= s.OnEvent

这应该在您丢失订阅者的句柄之前完成（即s超出范围或null之前）。您可以考虑在子程序中跟踪您的事件源，并使用Dispose方法取消订阅。

此外，正如其他人所说，您可以在订阅之前取消订阅:)我们现在确定您拥有所需的解决方案。

Answer 4

我遇到了同样的问题，用同步方法注册你的事件（我把它放在form_loaded中）

    private async void Window_Loaded(object sender, RoutedEventArgs e)
    {
        RefreshHierarchy.COIDConflict += RefreshHierarchy_COIDConflict;
    }

当事件被引发一次时，多次调用c＃事件处理程序

4 个答案: