private void btnCreate_Click(object sender, EventArgs e)
        {

            FileStream fs = new FileStream(@"E:\My File.dat", FileMode.OpenOrCreate);
            fs.Dispose();
            fs.Close();
            
        }

        private void btnWrite_Click(object sender, EventArgs e)
        {
            try
            {

                FileStream fs = new FileStream(@"E:\My File.dat", FileMode.Open);
                StreamWriter sw = new StreamWriter(fs);
                sw.WriteLine("It is just a test");
                sw.Flush();
                sw.Close();
                fs.Close();
                fs.Dispose();
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }

        }

------解决方案--------------------

C# code


 private void btnCreate_Click(object sender, EventArgs e)
  {
  if (!File.Exists(@"E:\My File.dat"))
  {
  File.CreateText(@"E:\My File.dat").Close();//此处释放数据流对文件的操作才会在下次BUTTON事件中写操作中不会被其他进程占有。
  }
  }