c# - "event"关键字的用途

Question

我最近经常使用 C# 和事件，但我才刚刚开始创建自己的事件并使用它们。我对为什么要使用 event 关键字有点困惑，我只使用委托(delegate)得到了相同的结果。

public partial class Form1 : Form
{
    ServerConnection connection = new ServerConnection();

    public Form1()
    {
        InitializeComponent();
        connection.ref = new del(MethOne);
        connection.ref += new del(MethTwo);
    }

    public void MethOne(object message)
    {
        MessageBox.Show((string)message);
    }

    public void MethTwo(object message)
    {
        MessageBox.Show((string)message);
    }

}


public delegate void del(string message);



public class ServerConnection
{
    private TcpListener tcpListener;
    public del ref;
    
    private List<NetworkStream> clientList = new List<NetworkStream>();

    public ServerConnection()
    {
        this.tcpListener = new TcpListener(IPAddress.Any, 3000);
        ThreadStart startListening = new ThreadStart(ListenForClients);
        Thread startThread = new Thread(startListening);
        startThread.Start();
    }


    public void ListenForClients()
    {
        tcpListener.Start();
        ParameterizedThreadStart handleClient = new ParameterizedThreadStart(HandleClient);

        while (true)
        {
            TcpClient newClient = tcpListener.AcceptTcpClient();
            Thread handleClientThread = new Thread(handleClient);
            handleClientThread.Start(newClient);
        }
    }


    public void HandleClient(object newClient)
    {
        NetworkStream clientStream = ((TcpClient)newClient).GetStream();
        clientList.Add(clientStream);

        BinaryFormatter formatter = new BinaryFormatter();
        string message;

        while (true)
        {
            message = (string)formatter.Deserialize(clientStream);
            ref((string)message);
        }
    }

Answer 1

event 关键字让您可以在声明中指定add 和remove 操作。

private Action _myEvent;

public event Action MyEvent
{
    add
    {
        Console.WriteLine("Listener added!");
        _myEvent += value;
    }
    remove
    {
        Console.WriteLine("Listener removed!");
        _myEvent -= value;
    }
}