1 private bool BHaveBeenTip=false; 2 private void label5_Click(object sender, EventArgs e) 3         { 4             var oFileBrowser = new FileBowser(); 5             if (oFileBrowser.ShowDialog() == DialogResult.OK) 6             { 7                 foreach (string fName in oFileBrowser.ListSelectedFile) 8                 { 9                         this.AddAttachment(fName, false, false);10                 }11                 bHasBeenTips = false;12             }13             oFileBrowser.Dispose();14         }15 16 private void AddAttachment(string aFileName, bool aIsDelete, bool aIsLargeAttachment)17 {18             if (attachList.Exists(o => o.Equals(aFileName, StringComparison.OrdinalIgnoreCase)))19             {20                      if (!bHasBeenTips)     //此处省略了  if(!bHasBeenTips==true)21                     { 22                 MessageBoxEx.ShowBox("不允许上传同名文件.", MessageBoxButtons.OK);23                 bHasBeenTips = true;24 }25                 return;26             }27             else28             {29                     ..................................30              }31 }