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
也许有点过量，但这是我通常解决问题的方式：
由于同步，此处不需要调用。BasicClassThreadExample对我来说只是一种布局，因此请根据您的实际需要进行更改。
这很简单，因为您不需要处理UI线程中的内容！
public partial class Form1 : Form
{
BasicClassThreadExample _example;
public Form1()
{
InitializeComponent();
_example = new BasicClassThreadExample();
_example.MessageReceivedEvent += _example_MessageReceivedEvent;
}
void _example_MessageReceivedEvent(string command)
{
listBox1.Items.Add(command);
}
private void button1_Click(object sender, EventArgs e)
{
listBox1.Items.Clear();
_example.Start();
}
}
public class BasicClassThreadExample : IDisposable
{
public delegate void MessageReceivedHandler(string msg);
public event MessageReceivedHandler MessageReceivedEvent;
protected virtual void OnMessageReceivedEvent(string msg)
{
MessageReceivedHandler handler = MessageReceivedEvent;
if (handler != null)
{
handler(msg);
}
}
private System.Threading.SynchronizationContext _SynchronizationContext;
private System.Threading.Thread _doWorkThread;
private bool disposed = false;
public BasicClassThreadExample()
{
_SynchronizationContext = System.ComponentModel.AsyncOperationManager.SynchronizationContext;
}
public void Start()
{
_doWorkThread = _doWorkThread ?? new System.Threading.Thread(dowork);
if (!(_doWorkThread.IsAlive))
{
_doWorkThread = new System.Threading.Thread(dowork);
_doWorkThread.IsBackground = true;
_doWorkThread.Start();
}
}
public void dowork()
{
string[] retval = System.IO.Directory.GetFiles(@"C:\Windows\System32", "*.*", System.IO.SearchOption.TopDirectoryOnly);
foreach (var item in retval)
{
System.Threading.Thread.Sleep(25);
_SynchronizationContext.Post(new System.Threading.SendOrPostCallback(delegate(object obj)
{
OnMessageReceivedEvent(item);
}), null);
}
}
protected virtual void Dispose(bool disposing)
{
if (!disposed)
{
if (disposing)
{
_doWorkThread.Abort();
}
disposed = true;
}
}
public void Dispose()
{
Dispose(true);
GC.SuppressFinalize(this);
}
~BasicClassThreadExample() { Dispose(false); }
}
其他回答
关于这个主题的另一个示例：我创建了一个抽象类UiSynchronizeModel，它包含一个公共方法实现：
public abstract class UiSynchronizeModel
{
private readonly TaskScheduler uiSyncContext;
private readonly SynchronizationContext winformsOrDefaultContext;
protected UiSynchronizeModel()
{
this.winformsOrDefaultContext = SynchronizationContext.Current ?? new SynchronizationContext();
this.uiSyncContext = TaskScheduler.FromCurrentSynchronizationContext();
}
protected void RunOnGuiThread(Action action)
{
this.winformsOrDefaultContext.Post(o => action(), null);
}
protected void CompleteTask(Task task, TaskContinuationOptions options, Action<Task> action)
{
task.ContinueWith(delegate
{
action(task);
task.Dispose();
}, CancellationToken.None, options, this.uiSyncContext);
}
}
模型或控制器类应从此抽象类派生。您可以使用任何模式（任务或手动管理的后台线程）并使用以下方法：
public void MethodThatCalledFromBackroundThread()
{
this.RunOnGuiThread(() => {
// Do something over UI controls
});
}
任务示例：
var task = Task.Factory.StartNew(delegate
{
// Background code
this.RunOnGuiThread(() => {
// Do something over UI controls
});
});
this.CompleteTask(task, TaskContinuationOptions.OnlyOnRanToCompletion, delegate
{
// Code that can safely use UI controls
});
还有另一个通用控件扩展。。
首先为Control类型的对象添加扩展方法
public static void InvokeIfRequired<T>(this T c, Action<T> action) where T : Control
{
if (c.InvokeRequired)
{
c.Invoke(new Action(() => action(c)));
}
else
{
action(c);
}
}
并从另一个线程调用类似的方法来访问UI线程中名为object1的控件：
object1.InvokeIfRequired(c => { c.Visible = true; });
object1.InvokeIfRequired(c => { c.Text = "ABC"; });
..或类似的
object1.InvokeIfRequired(c =>
{
c.Text = "ABC";
c.Visible = true;
}
);
简单的解决方案是使用Control.Invoke。
void DoSomething()
{
if (InvokeRequired) {
Invoke(new MethodInvoker(updateGUI));
} else {
// Do Something
updateGUI();
}
}
void updateGUI() {
// update gui here
}
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
也许有点过量，但这是我通常解决问题的方式：
由于同步，此处不需要调用。BasicClassThreadExample对我来说只是一种布局，因此请根据您的实际需要进行更改。
这很简单，因为您不需要处理UI线程中的内容！
public partial class Form1 : Form
{
BasicClassThreadExample _example;
public Form1()
{
InitializeComponent();
_example = new BasicClassThreadExample();
_example.MessageReceivedEvent += _example_MessageReceivedEvent;
}
void _example_MessageReceivedEvent(string command)
{
listBox1.Items.Add(command);
}
private void button1_Click(object sender, EventArgs e)
{
listBox1.Items.Clear();
_example.Start();
}
}
public class BasicClassThreadExample : IDisposable
{
public delegate void MessageReceivedHandler(string msg);
public event MessageReceivedHandler MessageReceivedEvent;
protected virtual void OnMessageReceivedEvent(string msg)
{
MessageReceivedHandler handler = MessageReceivedEvent;
if (handler != null)
{
handler(msg);
}
}
private System.Threading.SynchronizationContext _SynchronizationContext;
private System.Threading.Thread _doWorkThread;
private bool disposed = false;
public BasicClassThreadExample()
{
_SynchronizationContext = System.ComponentModel.AsyncOperationManager.SynchronizationContext;
}
public void Start()
{
_doWorkThread = _doWorkThread ?? new System.Threading.Thread(dowork);
if (!(_doWorkThread.IsAlive))
{
_doWorkThread = new System.Threading.Thread(dowork);
_doWorkThread.IsBackground = true;
_doWorkThread.Start();
}
}
public void dowork()
{
string[] retval = System.IO.Directory.GetFiles(@"C:\Windows\System32", "*.*", System.IO.SearchOption.TopDirectoryOnly);
foreach (var item in retval)
{
System.Threading.Thread.Sleep(25);
_SynchronizationContext.Post(new System.Threading.SendOrPostCallback(delegate(object obj)
{
OnMessageReceivedEvent(item);
}), null);
}
}
protected virtual void Dispose(bool disposing)
{
if (!disposed)
{
if (disposing)
{
_doWorkThread.Abort();
}
disposed = true;
}
}
public void Dispose()
{
Dispose(true);
GC.SuppressFinalize(this);
}
~BasicClassThreadExample() { Dispose(false); }
}
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