在C#中用到多執行緒處理一些功能，同時希望介面同步顯示更新，如果直接寫程式碼就會出現一些問題：

問題程式碼：

Thread ScanFileThread;

ScanFileThread = new Thread(WorkScanFileThread);
 this.ScanFileThread.Start();

WorkScanFileThread執行緒體程式碼：

private void WorkScanFileThread()
        {

            for (nDriveIndex = 0; nDriveIndex < DriveList.Count; nDriveIndex++)
            {
                this.listView3.Items[nDriveIndex].SubItems[2].Text =  "Scaning...";
                ...

                //指定的操作，操作結束後設置控制元件文字為完成

                ...

                SetListViewControlPropertyValue(this.listView3, nDriveIndex, 2, "Finished");
            }
        }

直接這樣呼叫，會在執行時丟擲異常，下面是異常資訊：

未處理 System.InvalidOperationException
  Message="Cross-thread operation not valid: Control 'listView3' accessed from a thread other than the thread it was created on."
  Source="System.Windows.Forms"
  StackTrace:
       at System.Windows.Forms.Control.get_Handle()
       at System.Windows.Forms.ListView.ListViewNativeItemCollection.DisplayIndexToID(Int32 displayIndex)
       at System.Windows.Forms.ListView.ListViewNativeItemCollection.get_Item(Int32 displayIndex)
       at System.Windows.Forms.ListView.ListViewItemCollection.get_Item(Int32 index)
       at Undelete_UI.Scan.WorkScanFileThread() in D:\C# Project\Undelete_UI - Copy\Undelete_UI\Scan.cs:line 123
       at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
       at System.Threading.ThreadHelper.ThreadStart()
  InnerException:

下面給出MSDN給出的解決方案：

摘取C#相關程式碼如下：

// This event handler creates a background thread that 
// attempts to set a Windows Forms control property 
// directly.
private void setTextUnsafeBtn_Click
    (object sender, EventArgs e)
{
    // Create a background thread and start it.
    this.demoThread =
        new Thread(new ThreadStart(this.ThreadProcUnsafe));
    this.demoThread.Start();

    // Continue in the main thread.  Set a textbox value that
    // would be overwritten by demoThread if it succeeded.
    // This value will appear immediately, then two seconds 
    // later the background thread will try to make its
    // change to the textbox.
    textBox1.Text = "Written by the main thread.";
}

// This method is executed on the worker thread. It attempts
// to access the TextBox control directly, which is not safe.
private void ThreadProcUnsafe()
{
    // Wait two seconds to simulate some background work
    // being done.
    Thread.Sleep(2000);

    this.textBox1.Text = 
        "Written unsafely by the background thread.";
}
 

上述程式碼並不能解決這個問題，在網上搜了一下，找到了這個方法，很好用：

摘抄部分原文：

Solution

Make sure you supply property value in correct type. In above example Text is a string property. This is why I am converting variablei to string.

自己根據上面的程式碼對程式進行了修改，修改後的程式碼如下：

delegate void SetControlValueCallback(Control oControl, string propName, object propValue);

        private void SetControlPropertyValue(Control oControl, string propName, object propValue)
        {

            if (oControl.InvokeRequired)
            {

                SetControlValueCallback d = new SetControlValueCallback(SetControlPropertyValue);

                oControl.Invoke(d, new object[] { oControl, propName, propValue });

            }

            else
            {

                Type t = oControl.GetType();

                PropertyInfo[] props = t.GetProperties();

                foreach (PropertyInfo p in props)
                {

                    if (p.Name.ToUpper() == propName.ToUpper())
                    {

                        p.SetValue(oControl, propValue, null);

                    }

                }

            }

        }

        //這是根據需要改寫的，用於給ListView指定列賦值的

        delegate void SetListViewControlValueCallback(ListView oControl, int nItem, int nSubItem, string propValue);

        private void SetListViewControlPropertyValue(ListView oControl, int nItem, int nSubItem, string propValue)
        {

            if (oControl.InvokeRequired)
            {

                SetListViewControlValueCallback d = new SetListViewControlValueCallback(SetListViewControlPropertyValue);

                oControl.Invoke(d, new object[] { oControl,nItem,nSubItem, propValue });

            }

            else
            {
                oControl.Items[nItem].SubItems[nSubItem].Text = propValue;

            }

        }
        private void WorkScanFileThread()
        {

            for (nDriveIndex = 0; nDriveIndex < DriveList.Count; nDriveIndex++)
            {
                SetControlPropertyValue(this.progressBar1, "value", 0);
                SetListViewControlPropertyValue(this.listView3, nDriveIndex,2, "Scaning...");
                //執行的功能操作

                SetListViewControlPropertyValue(this.listView3, nDriveIndex, 2, "Finished");
            }
        }

這樣問題就得到的完美的解決。

產生這個問題的主要原因是由於，控制元件不是執行緒安全性的，線上程中訪問非執行緒安全性的操作會被丟擲異常，提醒程式設計開發人員進行程式碼修改。

再給出兩個相關的連結