导出excel文件，旧文件内容不被覆盖
在一个winform中，写入以下代码导出一个excel文件，生成的文件名为tt1.xls，其sheet1.xls的表名改为"表1"。但是，在第二次保存excel文件后，生成另一个文件tt2.xls。但是tt1.xls的内容却被tt2.xls的内容覆盖了，求问原因及解决办法。如何能够在生成新的excel文件的同时，保持旧文件不被改变
程序代码：private void SaveTableToExcel(string filepath)
{
Microsoft.Office.Interop.Excel.Application app =
new Microsoft.Office.Interop.Excel.ApplicationClass();
try
{
app.Visible = false;
Excel.Workbook wBook = app.Application.Workbooks.Add(true);
Excel.Worksheet wSheet = wBook.Worksheets[1] as Excel.Worksheet;
wSheet.Name = "表1";
int rowNum = connsqlClass.hisListData.Count;
int columnNum = 6;
object[,] dataArray = new object[rowNum + 1, columnNum];
//将dataTable的标题导入到EXECL的标题（第一行）
dataArray[0, 0] = "时间";
dataArray[0, 1] = "编号";
dataArray[0, 2] = "名称";
dataArray[0, 3] = "位置";
dataArray[0, 4] = "类型";
dataArray[0, 5] = "值";
for (int i = 0; i < rowNum; i++)
{
dataArray[i + 1, 0] = connsqlClass.hisListTime[i];
dataArray[i + 1, 1] = No;
dataArray[i + 1, 2] = Name;
dataArray[i + 1, 3] = Place;
dataArray[i + 1, 4] = Type;
dataArray[i + 1, 5] = connsqlClass.hisListData[i];
}
wSheet.get_Range("A2", wSheet.Cells[rowNum + 1, columnNum]).Value2 = dataArray;
app.DisplayAlerts = false;
app.AlertBeforeOverwriting = false;
//保存工作簿
wBook.Save();
//保存excel文件
app.Save(filepath);
app.SaveWorkspace(filepath);
app.Quit();
app = null;
}
catch (Exception err)
{
MessageBox.Show("导出Excel出错！错误原因：" + err.Message, "提示信息", MessageBoxButtons.OK, MessageBoxIcon.Information);
}
finally { }
}
