第一个实验调用asynch方法-我需要所有这些代码

本文关键字：所有这些 代码 实验 调用 asynch 方法 第一个 | 更新日期: 2023-09-27 18:09:35

从未尝试使用Windows窗体进行异步调用。我不能使用新的aynch/await，因为我没有最近的Visual Studio/. net。我需要的是"执行一个请求很长时间的操作(填充一个列表)"，当它完成时，在TextBox上写入该列表的结果。

在网上搜索，我发现这个例子，似乎工作，但太符合我的意见(也许有一些快速和简单的):

private void button1_Click(object sender, EventArgs e)
{
    MyTaskAsync();
}
private void MyTaskWorker()
{
    // here I populate the list. I emulate this with a sleep of 3 seconds
    Thread.Sleep(3000);
}
private delegate void MyTaskWorkerDelegate();
public void MyTaskAsync()
{
    MyTaskWorkerDelegate worker = new MyTaskWorkerDelegate(MyTaskWorker);
    AsyncCallback completedCallback = new AsyncCallback(MyTaskCompletedCallback);
    AsyncOperation async = AsyncOperationManager.CreateOperation(null);
    worker.BeginInvoke(completedCallback, async);
}
private void MyTaskCompletedCallback(IAsyncResult ar)
{
    MyTaskWorkerDelegate worker = (MyTaskWorkerDelegate)((AsyncResult)ar).AsyncDelegate;
    AsyncOperation async = (AsyncOperation)ar.AsyncState;
    worker.EndInvoke(ar);
    AsyncCompletedEventArgs completedArgs = new AsyncCompletedEventArgs(null, false, null);
    async.PostOperationCompleted(delegate(object e) { OnMyTaskCompleted((AsyncCompletedEventArgs)e); }, completedArgs);
}
public event AsyncCompletedEventHandler MyTaskCompleted;
protected virtual void OnMyTaskCompleted(AsyncCompletedEventArgs e)
{
    if (MyTaskCompleted != null)
        MyTaskCompleted(this, e);
    // here I'll populate the textbox
    textBox1.Text = "... content of the Iteration on the List...";
}
我真的需要50行代码来做这么简单的操作吗?或者我可以去掉一些东西?我只需要一个简单的异步调用->完成后回调。

第一个实验调用asynch方法-我需要所有这些代码

您可以像这样使用c# 4.0的TPL:

private void button1_Click(object sender, EventArgs e)
{
    Task.Factory.StartNew(() => DoWork())
        .ContinueWith(t => UpdateUIWithResults(t.Result)
        , CancellationToken.None
        , TaskContinuationOptions.None
        , TaskScheduler.FromCurrentSynchronizationContext());
}

这将在线程池线程中启动DoWork，允许它在UI线程外进行处理，然后在UI线程中运行UpdateUIWithResults，将DoWork的结果传递给它。

您可以使用Task.Factory.StartNew将工作推入线程池。Task.ContinueWith会给你一个"完成回调"。

private void button1_Click(object sender, EventArgs e)
{
    var ui = TaskScheduler.FromCurrentSynchronizationContext();
    Task<List<T>> task = Task.Factory.StartNew(() => MyTaskWorker());
    task.ContinueWith(t => OnMyTaskCompleted(t), ui);
}
private List<T> MyTaskWorker()
{
    // here I populate the list. I emulate this with a sleep of 3 seconds
    Thread.Sleep(3000);
    return ...;
}
protected virtual void OnMyTaskCompleted(Task t)
{
    // here I'll populate the textbox with t.Result
    textBox1.Text = "... content of the Iteration on the List...";
}
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