Question

代码：

private delegate void NotificationDelegate(sis_company company, int days, string type, string param);

private NotificationDelegate _notDel;

private void Notifications(sys_company company, int days, string type, string param)
{
    if (*something*)
    {
        _notDel = SendEmails;
        _notDel.BeginInvoke(company, days, type, param, CallBackNotification, null);
    }
}

private void SendEmails(sys_company company, int days, string type, string param)
{
    //Here I'll send all e-mails.
}

private void CallBackNotification(IAsyncResult r)
{
    if (this.IsDisposed) return;

    try
    {
        _notDel.EndInvoke(r);
    }
    catch (Exception ex)
    {
        LogWriter.Log(ex, "EndInvoke Error");
    }
}

预期行为：

只要公司符合截止日期，就会调用Notifications方法。在初始化期间，方法为每个公司循环并在该循环内调用Notifications。

问题：

如您所见，_notDel是一个全局变量，稍后会用于EndInvoke delegate。问题是在第二次Notifications调用之后，对象不再相同，给出了错误说明：

＆＃34; 提供的IAsyncResult对象与此委托不匹配。＆＃34;

Answer 1

只需将notDel作为BeginInvoke的最后一个参数传递，然后使用r.AsyncState获取源代理。

//Call like this:

NotificationDelegate notDel = Notifications;
notDel.BeginInvoke(company, days, type, param, CallBackNotification, notDel);

//And inside the CallBack:

var del = r.AsyncState as NotificationDelegate;

if (del != null)
    del.EndInvoke(r);

使用代理的多个异步操作

1 个答案: