重新想象 Windows 8 Store Apps (42)

<Page
x:Class="XamlDemo.Thread.ThreadPool.DelayTimer"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="using:XamlDemo.Thread.ThreadPool"
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="btnCreateDelay" Content="延迟 3 秒后执行一个任务" Click="btnCreateDelay_Click_1" Margin="0 10 0 0" /> <Button Name="btnCancelDelay" Content="取消任务" Click="btnCancelDelay_Click_1" Margin="0 10 0 0" /> </StackPanel>
</Grid>
</Page>

/*
* 通过 ThreadPoolTimer 实现延迟执行（ThreadPoolTimer 在 Windows.System.Threading 命名空间下）
*
* ThreadPoolTimer - 计时器
* ThreadPoolTimer CreateTimer(TimerElapsedHandler handler, TimeSpan delay, TimerDestroyedHandler destroyed); - 创建一个用于延迟执行的计时器
* handler - 指定的延迟时间过后，所需要执行的方法
* delay - 延迟时间
* destroyed - 当 ThreadPoolTimer 完成了自身的使命后所执行的方法（比如延迟方法执行完了或计时器被取消了）
* Cancel() - 取消计时器
* Delay - 延迟时间，只读
*/using System;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.System.Threading;
using Windows.UI.Core;namespace XamlDemo.Thread.ThreadPool
{
public sealed partial class DelayTimer : Page
{
private ThreadPoolTimer _timer; public DelayTimer()
{
this.InitializeComponent();
} // 创建一个延迟计时器
private void btnCreateDelay_Click_1(object sender, RoutedEventArgs e)
{
_timer = ThreadPoolTimer.CreateTimer(
(timer) =>
{
var ignored = Dispatcher.RunAsync(CoreDispatcherPriority.High,
() =>
{
lblMsg.Text = "任务执行了";
});
},
TimeSpan.FromSeconds(),
(timer) =>
{
var ignored = Dispatcher.RunAsync(CoreDispatcherPriority.High,
() =>
{
lblMsg.Text += Environment.NewLine;
lblMsg.Text += "ThreadPoolTimer 的使命结束了";
});
}); lblMsg.Text = "延迟 3 秒后执行一个任务";
} // 取消计时器
private void btnCancelDelay_Click_1(object sender, RoutedEventArgs e)
{
if (_timer != null)
{
_timer.Cancel();
_timer = null; lblMsg.Text += Environment.NewLine;
lblMsg.Text += "任务取消了";
}
}
}
}

<Page
x:Class="XamlDemo.Thread.ThreadPool.PeriodicTimer"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="using:XamlDemo.Thread.ThreadPool"
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="btnCreatePeriodic" Content="执行一个周期任务" Click="btnCreatePeriodic_Click_1" Margin="0 10 0 0" /> <Button Name="btnCancelPeriodic" Content="取消任务" Click="btnCancelPeriodic_Click_1" Margin="0 10 0 0" /> </StackPanel>
</Grid>
</Page>

/*
* 通过 ThreadPoolTimer 实现周期执行（ThreadPoolTimer 在 Windows.System.Threading 命名空间下）
*
* ThreadPoolTimer - 计时器
* ThreadPoolTimer CreatePeriodicTimer(TimerElapsedHandler handler, TimeSpan period, TimerDestroyedHandler destroyed) - 创建一个用于延迟执行的计时器
* handler - 每个周期时间点到达之后，所需要执行的方法
* period - 周期执行的间隔时间
* destroyed - 当 ThreadPoolTimer 完成了自身的使命后所执行的方法（比如计时器被取消了）
* Cancel() - 取消计时器
* Period - 间隔时间，只读
*/using System;
using Windows.System.Threading;
using Windows.UI.Core;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;namespace XamlDemo.Thread.ThreadPool
{
public sealed partial class PeriodicTimer : Page
{
private ThreadPoolTimer _timer;
private int _periodicTimerCount = ; public PeriodicTimer()
{
this.InitializeComponent();
} // 创建一个周期计时器
private void btnCreatePeriodic_Click_1(object sender, RoutedEventArgs e)
{
_timer = ThreadPoolTimer.CreatePeriodicTimer(
(timer) =>
{
_periodicTimerCount++; var ignored = Dispatcher.RunAsync(CoreDispatcherPriority.High,
() =>
{
lblMsg.Text = "任务执行次数：" + _periodicTimerCount.ToString();
});
},
// 第 1 次执行 handler 是在计时器被创建的 100 毫秒之后，然后每 100 毫秒执行一次 handler
// 计时器会保证每 100 毫秒调用一次 handler，而不管上一次 handler 是否已执行完
TimeSpan.FromMilliseconds(),
(timer) =>
{
var ignored = Dispatcher.RunAsync(CoreDispatcherPriority.High,
() =>
{
lblMsg.Text += Environment.NewLine;
lblMsg.Text += "ThreadPoolTimer 的使命结束了";
});
}); lblMsg.Text = "任务执行次数：0";
} // 取消计时器
private void btnCancelPeriodic_Click_1(object sender, RoutedEventArgs e)
{
if (_timer != null)
{
_timer.Cancel();
_timer = null;
_periodicTimerCount = ; lblMsg.Text = "任务取消了";
}
}
}
}

<Page
x:Class="XamlDemo.Thread.ThreadPool.WorkItem"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="using:XamlDemo.Thread.ThreadPool"
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" /> <TextBlock Name="lblProgress" FontSize="14.667" /> <Button Name="btnCreateWorkItem" Content="在线程池中找一个线程去执行指定的方法" Click="btnCreateWorkItem_Click_1" Margin="0 10 0 0" />
<Button Name="btnCancelWorkItem" Content="取消任务" Click="btnCancelWorkItem_Click_1" Margin="0 10 0 0" /> <Button Name="btnCreateWorkItemByAwait" Content="通过 async await 简化“在线程池中找一个线程去执行指定的方法”" Click="btnCreateWorkItemByAwait_Click_1" Margin="0 30 0 0" /> </StackPanel>
</Grid>
</Page>

/*
* 通过 ThreadPool 实现“在线程池中找一个线程去执行指定的方法”（ThreadPool 在 Windows.System.Threading 命名空间下）
*
* ThreadPool - 线程池
* IAsyncAction RunAsync(WorkItemHandler handler, WorkItemPriority priority) - 在线程池中找一个线程去执行指定的方法，并指定其优先级
* handler - 需要调用的方法
* priority - 优先级（Windows.UI.Core.CoreDispatcherPriority 枚举：Low, Normal, High）
*
*
* 注：关于 IAsyncAction 请参见 XamlDemo/Thread/Async 中的说明
*/using System;
using System.Threading;
using Windows.Foundation;
using Windows.System.Threading;
using Windows.UI.Core;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;namespace XamlDemo.Thread.ThreadPool
{
public sealed partial class WorkItem : Page
{
private IAsyncAction _threadPoolWorkItem;
private ManualResetEvent _sleep = new ManualResetEvent(false); public WorkItem()
{
this.InitializeComponent();
} // 在线程池中找一个线程去执行指定的方法，并指定其优先级
private void btnCreateWorkItem_Click_1(object sender, RoutedEventArgs e)
{
_threadPoolWorkItem = Windows.System.Threading.ThreadPool.RunAsync(
(threadPoolWorkItem) =>
{
int percent = ; // 用于模拟执行进度（0 - 100）
while (percent < )
{
// 当前线程 sleep 100 毫秒
_sleep.WaitOne(); // 如果 IAsyncAction 被取消了则退出此 handler 的执行
if (threadPoolWorkItem.Status == AsyncStatus.Canceled)
break; percent++; var ignored = Dispatcher.RunAsync(CoreDispatcherPriority.High,
() =>
{
lblProgress.Text = "进度：" + percent.ToString() + "%";
});
}
},
WorkItemPriority.High); // IAsyncAction 完成之后（比如任务完成了或者任务取消了）
// 关于 IAsyncAction 的详细说明请参见 XamlDemo/Thread/Async
_threadPoolWorkItem.Completed = new AsyncActionCompletedHandler(
async (IAsyncAction threadPoolWorkItem, AsyncStatus status) =>
{
await Dispatcher.RunAsync(CoreDispatcherPriority.High,
() =>
{
switch (status)
{
case AsyncStatus.Completed:
lblMsg.Text = "任务完成了";
break;
case AsyncStatus.Canceled:
lblMsg.Text = "任务取消了";
break;
case AsyncStatus.Started:
case AsyncStatus.Error:
break;
}
});
}); lblProgress.Text = "进度：0%";
lblMsg.Text = "任务开始了";
} // 取消任务
private void btnCancelWorkItem_Click_1(object sender, RoutedEventArgs e)
{
if (_threadPoolWorkItem != null)
{
_threadPoolWorkItem.Cancel();
_threadPoolWorkItem = null;
}
} // 通过 async await 简化 ThreadPool.RunAsync() 的使用（关于 async 和 await 的详细说明请参见 XamlDemo/Thread/Async）
private async void btnCreateWorkItemByAwait_Click_1(object sender, RoutedEventArgs e)
{
lblProgress.Text = "";
lblMsg.Text = ""; string result = ""; await Windows.System.Threading.ThreadPool.RunAsync(
delegate
{
new ManualResetEvent(false).WaitOne();
result = "在线程池中找一个线程去执行指定的逻辑，然后通过 await 返回 UI 线程";
}); lblMsg.Text = result;
}
}
}