Windows 8 Store Apps學習(45) 多線程之非同步編程: IAsyncAction

多線程之非同步編程: IAsyncAction, IAsyncOperation

重新想象 Windows 8 Store Apps (45) - 多線程之非同步編程: IAsyncAction, IAsyncOperation, IAsyncActionWithProgress, IAsyncOperationWithProgress

介紹

重新想象 Windows 8 Store Apps 之 非同步編程

IAsyncAction - 無傳回值，無進度值

IAsyncOperation - 有傳回值，無進度值

IAsyncActionWithProgress - 無傳回值，有進度值

IAsyncOperationWithProgress - 有返回 值，有進度值

樣本

1、示範 IAsyncAction（無傳回值，無進度值）的用法

Thread/Async/IAsyncActionDemo.xaml

<Page    x:Class="XamlDemo.Thread.Async.IAsyncActionDemo"    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"    xmlns:local="using:XamlDemo.Thread.Async"    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"    mc:Ignorable="d">        <Grid Background="Transparent">        <StackPanel Margin="120 0 0 0">                <TextBlock Name="lblMsg" FontSize="14.667" />                <Button Name="btnCreateAsyncAction" Content="執行一個 IAsyncAction" Click="btnCreateAsyncAction_Click_1" Margin="0 10 0 0" />                <Button Name="btnCancelAsyncAction" Content="取消" Click="btnCancelAsyncAction_Click_1" Margin="0 10 0 0" />            </StackPanel>    </Grid></Page>

Thread/Async/IAsyncActionDemo.xaml.cs

/* * 示範 IAsyncAction（無傳回值，無進度值）的用法 *  * 註： * 1、WinRT 中的非同步功能均源自 IAsyncInfo * 2、IAsyncAction, IAsyncOperation<TResult>, IAsyncActionWithProgress<TProgress>, IAsyncOperationWithProgress<TResult, TProgress> 均繼承自 IAsyncInfo *  *  * 另： * Windows.System.Threading.ThreadPool.RunAsync() - 返回的就是 IAsyncAction */    using System.Runtime.InteropServices.WindowsRuntime;using System.Threading.Tasks;using Windows.Foundation;using Windows.UI.Xaml;using Windows.UI.Xaml.Controls;    namespace XamlDemo.Thread.Async{    public sealed partial class IAsyncActionDemo : Page    {        private IAsyncAction _action;            public IAsyncActionDemo()        {            this.InitializeComponent();        }            private IAsyncAction GetAsyncAction()        {            // 通過 System.Runtime.InteropServices.WindowsRuntime.AsyncInfo 建立 IAsyncAction            return AsyncInfo.Run(                (token) => // CancellationToken token                    Task.Run(                        () =>                        {                            token.WaitHandle.WaitOne(3000);                            token.ThrowIfCancellationRequested();                        },                        token));        }            private void btnCreateAsyncAction_Click_1(object sender, RoutedEventArgs e)        {            _action = GetAsyncAction();                // 可以 await _action                 // IAsyncAction 完成後            _action.Completed =                (asyncInfo, asyncStatus) => // IAsyncAction asyncInfo, AsyncStatus asyncStatus                {                    // AsyncStatus 包括：Started, Completed, Canceled, Error                    lblMsg.Text = "完成了，AsyncStatus: " + asyncStatus.ToString();                };                lblMsg.Text = "開始執行，3 秒後完成";        }            // 取消 IAsyncAction        private void btnCancelAsyncAction_Click_1(object sender, RoutedEventArgs e)        {            if (_action != null)                _action.Cancel();        }    }}