移除或插入新USB設備後的COM端口更新

Question

我想要一個控制元素來顯示正在運行的程序中關於連接的USB設備的更改。搜索後，我設法找到USB設備並將其打印出來。我也處理獲取有關移除和連接的信息。

但現在有一個問題，當我結合兩個部分它不起作用。 這裏是我的代碼：

namespace usbPortAbfrage 
{ 
    public partial class Form1 : Form 
    { 
     ArrayList result = new ArrayList(); 
     public Form1() 
     { 
      InitializeComponent(); 
      bla(); 
     } 

     public ArrayList GetComFriendlyNames() 
     { 
      ArrayList names = new ArrayList(); 
      try 
      { 
       ManagementObjectSearcher searcher = 
        new ManagementObjectSearcher("root\\WMI", 
        "SELECT InstanceName, PortName FROM MSSerial_PortName"); 

       foreach (ManagementObject port in searcher.Get()) 
       { 
        names.Add(port["PortName"]); 
       } 
      } 
      catch (ManagementException) 
      { 
      } 
      return names; 
     } 

     protected override void WndProc(ref Message m) 
     { 
      base.WndProc(ref m); 

      if (m.WParam.ToInt32() == 0x8004) 
      { 
       MessageBox.Show("Gerät entfernt"); 
       richTextBox1.Clear(); 
       bla(); 
      } 

      if (m.WParam.ToInt32() == 0x8000) 
      { 
       MessageBox.Show("Gerät angeschlossen"); 
       richTextBox1.Clear(); 
       bla(); 
      } 
     } 

     public void bla() 
     { 
      richTextBox1.Clear(); 

      ArrayList test = GetComFriendlyNames(); 

      foreach (string name in test) 
      { 
       richTextBox1.AppendText(name + "\n"); 
      } 
     }  
    } 
} 

Answer 1

這是我的測試中我調試代碼，試圖複製我似乎無法要麼打事件代碼的問題。 （IE沒有這個代碼將無法正常工作，這不是答案/解決方案，但我不能把它放入一個評論，請不要將其否決！）

public partial class Form1 : Form 
{ 
    private const int WM_ACTIVATEAPP = 0x001C; 
    private const int DBT_DEVICEARRIVAL = 0x8000;    // system detected a new device  
    private const int DBT_DEVICEREMOVEPENDING = 0x8003;   // about to remove, still available  
    private const int DBT_DEVICEREMOVECOMPLETE = 0x8004; 
    private bool appActive = true; 

    public Form1() 
    { 
     this.Size = new System.Drawing.Size(300, 300); 
     this.Text = "Form1"; 
     this.Font = new System.Drawing.Font("Microsoft Sans Serif", 18F, System.Drawing.FontStyle.Bold, System.Drawing.GraphicsUnit.Point, ((System.Byte)(0))); 
    } 

    protected override void OnPaint(PaintEventArgs e) 
    { 
     // Paint a string in different styles depending on whether the 
     // application is active. 
     if (appActive) 
     { 
      e.Graphics.FillRectangle(SystemBrushes.ActiveCaption, 20, 20, 260, 50); 
      e.Graphics.DrawString("Application is active", this.Font, SystemBrushes.ActiveCaptionText, 20, 20); 
     } 
     else 
     { 
      e.Graphics.FillRectangle(SystemBrushes.InactiveCaption, 20, 20, 260, 50); 
      e.Graphics.DrawString("Application is Inactive", this.Font, SystemBrushes.ActiveCaptionText, 20, 20); 
     } 
    } 

    [System.Security.Permissions.PermissionSet(System.Security.Permissions.SecurityAction.Demand, Name = "FullTrust")] 
    protected override void WndProc(ref Message m) 
    { 
     // Listen for operating system messages. 
     switch (m.Msg) 
     { 
      // The WM_ACTIVATEAPP message occurs when the application 
      // becomes the active application or becomes inactive. 
      case WM_ACTIVATEAPP: 

       // The WParam value identifies what is occurring. 
       appActive = (((int)m.WParam != 0)); 

       // Invalidate to get new text painted. 
       this.Invalidate(); 

       break; 
      case DBT_DEVICEARRIVAL: 
       MessageBox.Show("Connected!"); 
       break; 
      case DBT_DEVICEREMOVECOMPLETE: 
       MessageBox.Show("Disconnected!"); 
       break; 
     } 
     base.WndProc(ref m); 
    } 
} 

鏈接到MSDN類似的問題：http://social.msdn.microsoft.com/Forums/en-US/csharpgeneral/thread/ea183afd-d070-4abd-8e00-a1784fdfedc5/