.NET 4.5 异步IO 相关实例

在c/s架构中，不管是传统的winform还是wpf都可能会遇到进行异步操作文件的时候。文件小还好说，直接写操作代码。

如果是大文件很多时候做成异步的操作。在界面上显示一个进度条什么的，后台使用一个backgroundworker来做。在这里告诉大家在.net framework4.5中支持异步io的操作。大大简化之前些的异步方法代码。

使用backgroundworker代码

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");
        }

以上应该是最基本的操作了，代码是不是很多？看看.net framework 4.5的写法吧。

private async void button_click_2(object sender, routedeventargs 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('\\'))))
                    {
                        await sourcestream.copytoasync(destinationstream);
                    }
                }
            }
            messagebox.show("ok");
        }

希望能帮助到一些人。