C#类似windows资源管理器-获取文件图标

//根据扩展名获取图标  
public int fileExtIcon(string typeExt, FileInfo f)  
{  
    if (!extIcon.ContainsKey(typeExt) && typeExt != ".exe")  
    {  
        RegistryKey regRead = Registry.ClassesRoot.OpenSubKey(typeExt);  
        if (regRead == null) { return 0; }  
        string subKey = regRead.GetValue("").ToString();  
        RegistryKey regRead1 = Registry.ClassesRoot.OpenSubKey(subKey);  
        if (regRead1 == null) { return 0; }  
        RegistryKey subKey1 = regRead1.OpenSubKey("DefaultIcon");  
        string defaultIcon = subKey1.GetValue("").ToString();  
        string[] defIcon = defaultIcon.Split(‘,‘);  
        Icon ic = getExtractIcon(defIcon[0], int.Parse(defIcon[1]));  
        TreeImageList.Images.Add(ic);  
        extIcon.Add(typeExt, i++);  
        return 0;  
    }  
    else if (typeExt == ".exe")  
    {  
        string fullPath = f.FullName;  
        Icon ic = getExtractIcon(fullPath,0);  
        if (ic != null)  
        {  
            TreeImageList.Images.Add(ic);  
            extIcon.Add(typeExt, i++);  
        }  
    }  
    return 0;  
}  

//获取系统图标  
[DllImport("shell32.dll")]  
public static extern int ExtractIcon(IntPtr h, string strx, int ii);  
public Icon getExtractIcon(string fileName,int iIndex)  
{  
    try  
    {  
        IntPtr hIcon = (IntPtr)ExtractIcon(this.Handle, fileName, iIndex);  
        if (hIcon != IntPtr.Zero)  
        {  
            Icon icon = Icon.FromHandle(hIcon);  
            return icon;  
        }  
    }  
    catch(Exception e)  
    {  
        MessageBox.Show(e.Message,"错误提示",0,MessageBoxIcon.Error);  
    }  
    return null;  
}