Question

我想自动检测SerialPort。所以我有五个组合框来选择SerialPort这样的参数：

<TextBlock Text="BaudRate"/>
<ComboBox x:Name="comboBox_BaudRate" SelectedIndex="2">
    <ComboBoxItem>9600</ComboBoxItem>
    <ComboBoxItem>14400</ComboBoxItem>
    <ComboBoxItem>19200</ComboBoxItem>
    <ComboBoxItem>38400</ComboBoxItem>
    <ComboBoxItem>56000</ComboBoxItem>
    <ComboBoxItem>115200</ComboBoxItem>
</ComboBox>

<TextBlock Text="DataBit"/>
<ComboBox x:Name="comboBox_DataBit" SelectedIndex="0" >
    <ComboBoxItem>8</ComboBoxItem>
    <ComboBoxItem>7</ComboBoxItem>
</ComboBox>

<TextBlock Text="Parity" />
<ComboBox x:Name="comboBox_Parity" SelectedIndex="0" >
    <ComboBoxItem>None</ComboBoxItem>
    <ComboBoxItem>Odd</ComboBoxItem>
    <ComboBoxItem>Even</ComboBoxItem>
</ComboBox>

<TextBlock Text="StopBit" />
<ComboBox x:Name="comboBox_StopBit" SelectedIndex="0" >
    <ComboBoxItem>1</ComboBoxItem>
    <ComboBoxItem>2</ComboBoxItem>
</ComboBox>

<Button x:Name="btn_Auto_Detect" Click="btn_Find_Click" />

当我点击btn_Auto_Detect时，我想将这些组合框的不同参数设置为try_Port，并尝试使用try_Port发送数据来连接我的设备。问题是这个动作可能需要几分钟。所以我可以在这个时候取消这个任务。

public bool cancelFlag = false;
private void btn_Find_Click(object sender, RoutedEventArgs e)
{
    var tokenSource = new CancellationTokenSource();
    var token = tokenSource.Token;

    if(cancelFlag)
    {
        cancelFlag = false;
        tokenSource.Cancel();
        Hint("Searching Canceled!");
    }
    else
    {
        cancelFlag = true;
        Hint("Start Searching...");
    }

    Task.Factory.StartNew(() =>
        {
            if(!token.IsCancellationRequested)
            {
                Matching_Process_Thread();
            }
            else
            {
                return;
            }
        }, token).ContinueWith(task =>
        {
           ...

        }, token, TaskContinuationOptions.None, TaskScheduler.FromCurrentSynchronizationContext());
}


public static SerialPort try_port = new SerialPort();
private void Matching_Process_Thread()
{
    int tryNumber = 0;
    //Loop searching the portname, baudrate, databit, parity, stopbit
    for (int i = 0; i < comboBox_Port.Items.Count; i++)
    {
        try_port.PortName = comboBox_Port.Items[i].ToString();
        for (int j = 0; j < comboBox_BaudRate.Items.Count; j++)
        {
            for (int k = 0; k < comboBox_DataBit.Items.Count; k++)
            {
                for (int m = 0; m < comboBox_Parity.Items.Count; m++)
                {
                    for (int n = 0; n < comboBox_StopBit.Items.Count; n++)
                    {
                        //Here I want to update the UI                       
                        this.Dispatcher.BeginInvoke(
                        DispatcherPriority.SystemIdle, new Action<int, int, 
                        int, int>(Update_ComboBoxs), j, k, m, n);

                        if(!try_port.isOpen){ try_port.Open(); }
                        ...
                        //if get response, return
                        //else close this try_port.close() and return;
                     }
                 }
            }
        }
   }

    private void Update_ComboBoxs(int baudrate, int databit, int parity, int stopbit)
    {
        this.comboBox_BaudRate.SelectedIndex = baudrate;
        try_port.BaudRate = int.Parse(comboBox_BaudRate.Text);

        this.comboBox_DataBit.SelectedIndex = databit;
        try_port.DataBits = int.Parse(comboBox_DataBit.Text);

        this.comboBox_Parity.SelectedIndex = parity;
        switch (parity)
        {
            case 0:
                try_port.Parity = Parity.None;
                break;
            case 1:
                try_port.Parity = Parity.Odd;
                break;
            case 2:
                try_port.Parity = Parity.Even;
                break;
            default:break;
        }

        this.comboBox_StopBit.SelectedIndex = stopbit;
        switch (stopbit)
        {
            case 0:
                try_port.StopBits = StopBits.One;
                break;
            case 1:
                try_port.StopBits = StopBits.Two;
                break;
            default:break;
        }
    }

但这永远不会停止任务，我也不知道为什么！

我该如何解决这个问题，还是有更好的方法来实现我的目标？提前谢谢！

Answer 1

您需要检查循环中的IsCancellationRequested属性。你在任务开始时检查一次，然后再不检查。

我会在较慢的操作之前检查它，如果有多个慢速操作则立即检查。然后退出你的功能，取消将按你的要求工作。

如何启动任务并取消它？

1 个答案: