从另一个线程更新标签的最简单方法是什么?

我在thread1上运行了一个Form,然后我开始另一个线程(thread2)。当thread2处理一些文件时,我想用thread2工作的当前状态更新表单上的标签。

我怎么能这样做?


当前回答

最简单的方法是调用如下:

 Application.Current.Dispatcher.Invoke(new Action(() =>
             {
                    try
                    {
                        ///
                    }
                    catch (Exception)
                    {
                      //
                    }


                    }
     ));

其他回答

创建类变量:

SynchronizationContext _context;

在创建UI的构造函数中设置它:

var _context = SynchronizationContext.Current;

要更新标签时:

_context.Send(status =>{
    // UPDATE LABEL
}, null);

Marc Gravell的.NET 4最简单解决方案的变体:

control.Invoke((MethodInvoker) (() => control.Text = "new text"));

或者改用Action委托:

control.Invoke(new Action(() => control.Text = "new text"));

请参阅此处了解两者的比较:MethodInvoker与Action for Control.BeginInvoke

在这个问题上,大多数其他答案对我来说都有点复杂(我是C#新手),所以我写了我的答案:

我有一个WPF应用程序,并定义了如下工作人员:

问题:

BackgroundWorker workerAllocator;
workerAllocator.DoWork += delegate (object sender1, DoWorkEventArgs e1) {
    // This is my DoWork function.
    // It is given as an anonymous function, instead of a separate DoWork function

    // I need to update a message to textbox (txtLog) from this thread function

    // Want to write below line, to update UI
    txt.Text = "my message"

    // But it fails with:
    //  'System.InvalidOperationException':
    //  "The calling thread cannot access this object because a different thread owns it"
}

解决方案:

workerAllocator.DoWork += delegate (object sender1, DoWorkEventArgs e1)
{
    // The below single line works
    txtLog.Dispatcher.BeginInvoke((Action)(() => txtLog.Text = "my message"));
}

我还没有弄清楚上面这句话的意思,但它奏效了。

对于WinForms:

解决方案:

txtLog.Invoke((MethodInvoker)delegate
{
    txtLog.Text = "my message";
});

将一些公共变量放在一个单独的类中以保存值。

例子:

public  class data_holder_for_controls
{
    // It will hold the value for your label
    public string status = string.Empty;
}

class Demo
{
    public static  data_holder_for_controls d1 = new data_holder_for_controls();

    static void Main(string[] args)
    {
        ThreadStart ts = new ThreadStart(perform_logic);
        Thread t1 = new Thread(ts);
        t1.Start();
        t1.Join();
        //your_label.Text=d1.status; --- can access it from any thread
    }

    public static void perform_logic()
    {
        // Put some code here in this function
        for (int i = 0; i < 10; i++)
        {
            // Statements here
        }
        // Set the result in the status variable
        d1.status = "Task done";
    }
}

前面回答中的Invoke内容都不是必需的。

您需要查看WindowsFormsSynchronizationContext:

// In the main thread
WindowsFormsSynchronizationContext mUiContext = new WindowsFormsSynchronizationContext();

...

// In some non-UI Thread

// Causes an update in the GUI thread.
mUiContext.Post(UpdateGUI, userData);

...

void UpdateGUI(object userData)
{
    // Update your GUI controls here
}