C#读写Excel

Dictionary<int, string>  dict = new Dictionary<int, string>();
List<string> list = new List<string>();
object missing = Missing.Value;
Application excel = new Application();
excel.Visible = false;
excel.UserControl = true;
Workbook book = excel.Application.Workbooks.Open(file, missing, false,
    missing, missing, missing, missing, missing, missing, true,
    missing, missing, missing, missing, missing);
Worksheet sheet = (Worksheet)book.Worksheets.get_Item(4);
int rowCount = sheet.UsedRange.Cells.Rows.Count;
int success = 0;
for (int i = 2; i < rowCount; i++)
{
    Range r1 = sheet.Cells.get_Range(string.Format("Q{0}", i), missing);
    object isOffline = r1.Value;
    if (isOffline != null && (isOffline.ToString() == "是" || isOffline.ToString() == "？"))
    {
        Range r2 = sheet.Cells.get_Range(string.Format("A{0}", i), missing);
        object obj = r2.Value;
        string value = obj == null ? "" : obj.ToString();
        dict.Add(i, value);
        if (!value.Contains("@"))
        {
            list.Add(value);
        }
        if (value != "")
        {
            BsDicFormVersion model = models.FirstOrDefault(a => a.Version_Name == value);
            if (model != null)
            {
                sheet.Cells[i, 19] = model.Version_Name;
                sheet.Cells[i, 20] = model.Form_Version;
                sheet.Cells[i, 21] = model.Template_File_Path;
                sheet.Cells[i, 22] = model.Input_Type;
                sheet.Cells[i, 23] = model.Jsp_Path;
                sheet.Cells[i, 24] = model.Open_Kind;
                success++;
            }
        }
    }
}
Console.WriteLine(success);
sheet.SaveAs("D:\\15.xlsx");
book.Close();
excel.Quit();