C# - 让 UI 像无限循环一样运行，直到按下按钮

Question

我在 C# 中编写了一个代码，其中我从 Access 数据库中提取了一些记录，但是我需要在进行下一次迭代时依赖于单击按钮。我尝试了一些 Thread 或 Tasks ，但它没有用，因为它阻止了 UI 我需要它被看到和点击。

代码如下：

    bool nextClick = false ;

                while (readerSelect.Read())
                {

                    // show the correct panel
                    if (string.Compare(readerSelect[2].ToString(), "P1") == 0)
                    {
                        // panel with type 1
                        textBoxP1Text1.Text = readerSelect[3].ToString();
                        textBoxP1Text2.Text = readerSelect[4].ToString();
                        pictureBoxP1Image.ImageLocation = readerSelect[6].ToString();

                    }
                    else
                    {
                        // panel with type 2
                        textBoxP1Text2.Text = readerSelect[5].ToString();
                    }

    //this while need to be kind of infinite so the interation can't be processed and 
   //so when i need to change iteration i click the buttonNext 
                    while (!nextClick) {
                    startWhile:; 
                       MethodInvoker mi = delegate () {
                           if (nextClick)
                           {
                               Application.DoEvents(); 
                              // System.Windows.Forms.Application.Run();
                           }

                        };
                        this.Invoke(mi);
                        //break;
                        goto startWhile; 
                    }

 private void buttonNext_Click(object sender, EventArgs e)
    {
        // click on the next button
        nextClick = true; 
    }

Answer 1

您可以在异步任务中使用信号量，在每次单击时让按钮 Release 使用它，并让 while 循环在每次通过时等待它。这是一个简单的示例，使用添加了 button1 和 label1 的表单：

public partial class Form1 : Form
{
    private readonly SemaphoreSlim signal = new SemaphoreSlim(0, int.MaxValue);

    public Form1()
    {
        this.InitializeComponent();
        this.RunLoop();
    }

    private async void RunLoop()
    {
        var i = 0;
        while (true)
        {
            this.label2.Text = $"Enqueued: {this.signal.CurrentCount}";
            await this.signal.WaitAsync(); // Wait button click async
            await Task.Delay(1000); // Simulate work
            this.label1.Text = $"Completed: {++i}";
        }
    }

    private void button1_Click(object sender, EventArgs e)
    {
        this.signal.Release();
        this.label2.Text = $"Enqueued: {this.signal.CurrentCount + 1}";
        // Or if you want to limit the # people can queue up, then put this whole
        // thing in an `if (signal.CurrentCount < myLimit)` block, and optionally
        // disable the button once limit has been reached, and re-enable it right
        // before the `WaitAsync` call above.
    }
}

Answer 2

虽然 Dax Fohl 的回答有效，但您的设计似乎有问题。我认为您在 Form class.

中执行了过多的业务逻辑，这违反了 Single Responsibility Principle

我建议将业务逻辑分解成它自己的 class。然后，无需运行遍历循环中的所有内容，您只需让按钮单击事件处理下一条记录并显示结果。这是我的意思的一个例子：

public partial class Form1 : Form
{
    private readonly DataProcessor dataProcessor = new DataProcessor();

    public Form1()
    {
        this.InitializeComponent();
    }

    private void button1Next_Click(object sender, EventArgs e)
    {
        this.buttonNext.Enabled = false;
        this.ProcessNext();
    }

    private async void ProcessNext()
    {
        string s = await this.dataProcessor.ProcessNext();
        this.textBoxP1Text1.Text = s;
        this.buttonNext.Enabled = true;
    }
}

public class DataProcessor
{
    private readonly Random r = new Random(); // Or reader or whatever.

    public async Task<string> ProcessNext() // Just using `string` as an example.
    {
        await Task.Delay(1000);
        return this.r.Next().ToString();
    }
}

我觉得这样以后会更容易理解，也更容易维护。当一个新的团队成员看到信号量的东西（或你未来的自己）时，很难 understand/remember 那些东西的意义是什么。在这里，您只有一个本地函数，它只做一件事并且很容易理解。

C# - 让 UI 像无限循环一样运行，直到按下按钮

C# - Make UI function during like a infinite loop until button pressed

c#

oledb

winforms