在C/S架構中，不管是傳統的winform還是wpf都可能會遇到進行異步操作文件的時候。文件小還好說，直接寫操作代碼。

如果是大文件很多時候做成異步的操作。在界面上顯示一個進度條什么的，后臺使用一個backgroundworker來做。在這里告訴大家在.NET Framework4.5中支持異步IO的操作。大大簡化之前些的異步方法代碼。

使用backgroundworker代碼
代碼如下:
View Code

private void Button_Click_3(object sender, RoutedEventArgs e)
        {
            System.ComponentModel.BackgroundWorker bak = new System.ComponentModel.BackgroundWorker();
            bak.DoWork += bak_DoWork;
            bak.RunWorkerCompleted += bak_RunWorkerCompleted;
            bak.RunWorkerAsync();         
        }

        void bak_DoWork(object sender, System.ComponentModel.DoWorkEventArgs e)
        {
            string sourceDir = @"E:/";
            string endDir = @"F:/";
            foreach (string filename in Directory.EnumerateFiles(sourceDir))
            {
                using (FileStream SourceStream = File.Open(filename, FileMode.Open))
                {
                    using (FileStream DestinationStream = File.Create(endDir + filename.Substring(filename.LastIndexOf('//'))))
                    {
                        SourceStream.CopyTo(DestinationStream);
                    }
                }
            }
        }

        void bak_RunWorkerCompleted(object sender, System.ComponentModel.RunWorkerCompletedEventArgs e)
        {
            MessageBox.Show("ok");