C# （xlApp.工作簿中的xl.Workbook wb） { if（wb.FullName==xlFileName） { 如果（！xlWb） .床单 .Cast（） .选择（s=>s.Name） .Contains（名称）） { Show（“Excel工作簿中不存在工作表名称！”）； 返回； } xlWs=xlWb.Sheets[xlSheetName]； } } } 捕获（例外情况除外） { //捕捉错误 } } }

添加到Armbrat的解决方案中；这对我很有用：

// To use currently running instance of Excel 
Excel.Application objApp = 
(Excel.Application)System.Runtime.InteropServices.Marshal.GetActiveObject("Excel.Application");
    Excel.Workbooks objBooks;    
    Excel._Workbook objBook;
            
objBooks = objApp.Workbooks;    // Adds to the workbooks collection - objBooks.Count will now == 1

objBook = objBooks["Name of workbook"]; // No filename extension, just the name shown in the workbook window title bar

---

这似乎是对Excel应用程序

app！=空

但

应用程序工作簿.Count

仍为

0

。为什么它不能获取对已打开工作簿的引用？Excel互操作可能很烦人。最重要的是确保始终释放Excel应用程序对象。否则，将运行EXCEL.exe的重影实例。因此，请关闭所有Excel实例，然后重试该代码。最后，阅读这篇关于如何正确发布Excel的文章，查看此线程以获得正确的清理和讨论：我不认为我的问题与发布应用程序有关，尽管该链接有帮助。。。但我甚至无法访问打开的工作簿。。我可以访问Excel应用程序本身，但找不到要验证的工作簿-您是否检查了在task manager中打开了多少Excel实例？这个答案似乎与问题无关。

app = (Excel.Application)Marshal.GetActiveObject("Excel.Application");

try
{
  Microsoft.Office.Interop.Excel.Application app = 
      System.Runtime.InteropServices.Marshal.GetActiveObject("Excel.Application");
}
catch
{
  // Excel is not running.
}

 String constr = @"Provider=Microsoft.ACE.OLEDB.12.0;Data Source="+txtSourceFile.Text+";Extended Properties='Excel 8.0;HDR=YES;';";
        String constr2 = @"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" + txtLibrary.Text + ";Extended Properties='Excel 8.0;HDR=YES;';";

        OleDbConnection con = new OleDbConnection(constr);
        OleDbConnection con2 = new OleDbConnection(constr2);
        OleDbConnection con3 = new OleDbConnection(constr);

        OleDbCommand oconn = new OleDbCommand("Select * From [eudra$]", con);
        OleDbCommand oconn2 = new OleDbCommand("Select * From [Sheet1$]", con2);
        OleDbCommand oconn3 = new OleDbCommand("Select * From [eudra$] where EXAMPARM in ('with one or more serious adverse events','with one or more non-serious adverse events that met the incidence cutoff')", con);

        if (txtSourceFile.Text != "")
        {
            con.Open();
            con2.Open();
            con3.Open();

            OleDbDataAdapter sda = new OleDbDataAdapter(oconn);
            OleDbDataAdapter sda2 = new OleDbDataAdapter(oconn2);
            OleDbDataAdapter sda3 = new OleDbDataAdapter(oconn3);


            DataTable data = new DataTable();
            sda.Fill(data);

            DataTable data2 = new DataTable();
            sda2.Fill(data2);

            DataTable data3 = new DataTable();
            sda3.Fill(data3);

            var test = JoinDataTables(data, data2, (row1, row2) => (row1.Field<string>("BODY_SYS").ToUpper() == row2.Field<string>("Term").ToUpper() ));

            data3.Merge(test, true);

            dgvImp.DataSource = data3;
            con.Close();
        }

// creating Excel Application
Microsoft.Office.Interop.Excel._Application app = new Microsoft.Office.Interop.Excel.Application();

// creating new WorkBook within Excel application
Microsoft.Office.Interop.Excel._Workbook workbook = app.Workbooks.Add(Type.Missing);

// creating new Excelsheet in workbook
Microsoft.Office.Interop.Excel._Worksheet worksheet = null;

// see the excel sheet behind the program
app.Visible = true;

// get the reference of first sheet. By default its name is Sheet1.
// store its reference to worksheet
worksheet = workbook.Sheets["Sheet1"];
worksheet = workbook.ActiveSheet;

// changing the name of active sheet
worksheet.Name = "Exported from gridview";

try
{
    // storing header part in Excel
    for (int i = 1; i < dgvRESULTS.Columns.Count + 1; i++)
    {
        worksheet.Cells[1, i] = dgvRESULTS.Columns[i - 1].HeaderText;
        worksheet.Cells[1, i].Interior.Color = System.Drawing.Color.LightYellow;
    }

    // storing Each row and column value to excel sheet
    for (int i = 0; i < dgvRESULTS.Rows.Count - 1; i++)
    {
        for (int j = 0; j < dgvRESULTS.Columns.Count; j++)
        {
            if (dgvRESULTS.Rows[i].Cells[j].Value != null)
            {
                worksheet.Cells[i + 2, j + 1] = dgvRESULTS.Rows[i].Cells[j].Value.ToString();
                //worksheet.Cells[i + 2, j + 1].Interior.Color = System.Drawing.ColorTranslator.ToOle(dgvRESULTS.Rows[i].DefaultCellStyle.BackColor);
            }
            else
            {
                worksheet.Cells[i + 2, j + 1] = "";
            }
        }
    }
}
catch(NullReferenceException ne)
{
}
string filePath = Environment.GetFolderPath(Environment.SpecialFolder.Desktop);
// save the application
workbook.SaveAs(filePath +"\\output.xls", Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Microsoft.Office.Interop.Excel.XlSaveAsAccessMode.xlExclusive, Type.Missing, Type.Missing, Type.Missing, Type.Missing);

// Exit from the application
app.Quit();

using Excel = Microsoft.Office.Interop.Excel;

public Excel.Application xlApp;
public Excel.Workbook xlWorkBook;
public Excel.Worksheet xlWorkSheet;

public void ExcelTransferData()
{
   xlApp = new Microsoft.Office.Interop.Excel.Application();
   xlApp = (Excel.Application)System.Runtime.InteropServices.Marshal.GetActiveObject("Excel.Application");

   foreach (Excel.Workbook item in xlApp.Workbooks)
   {
        //Select the excel target 'NAME'
        if (item.Name == "Template.xlsx")
        {
            xlWorkBook = item; 
            break;
        }

        //Select the target workbook
        xlWorkSheet = xlWorkBook.Sheets[1] as Excel.Worksheet;
        //Set cell value
        xlWorkSheet.Cells[5, 1] = "davinceleecode";
   }
}

using System.Collections.Generic;
using System.IO;
using System.Linq;
using wf = System.Windows.Forms;
using xl = Microsoft.Office.Interop.Excel;

public static class ExcelTest
{   
    public xl.Application xlApp = null;
    public xl.Workbook xlWb = null;
    public xl.Worksheet xlWs = null;

    public static bool IsXlFileOpen(string xlFileName)
    {       
        try
        {       
            if (!File.Exists(xlFileName))
            {
                wf.MessageBox.Show("Excel File does not exists!");
                return false;
            }

            try
            {
                xlApp = (xl.Application)Marshal.GetActiveObject("Excel.Application");
            }
            catch (Exception ex)
            {
                return false;
            }

            foreach (xl.Workbook wb in xlApp.Workbooks)
            {
                if (wb.FullName == xlFileName)
                {
                    xlWb = wb;
                    return true;
                }
            }

            return false;
        }
        catch (Exception ex)
        {
            return false;
        }
    }

    public static void GetXlSheet(string xlFileName,
                                    string xlSheetName)
    {
        try
        {
            if (!File.Exists(xlFileName))
            {
                wf.MessageBox.Show("Excel File does not exists!");
                return false;
            }

            xlApp = (xl.Application)Marshal.GetActiveObject("Excel.Application");
            foreach (xl.Workbook wb in xlApp.Workbooks)
            {
                if (wb.FullName == xlFileName)
                {
                    if (!xlWb
                        .Sheets
                        .Cast<xl.Worksheet>()
                        .Select(s => s.Name)
                        .Contains(xlSheetName))
                    {
                        wf.MessageBox.Show("Sheet name does not exist in the Excel workbook!");
                        return;
                    }
                    xlWs = xlWb.Sheets[xlSheetName];
                }
            }
        }
        catch (Exception ex)
        {
            // catch errors
        }
    }   
}

// To use currently running instance of Excel 
Excel.Application objApp = 
(Excel.Application)System.Runtime.InteropServices.Marshal.GetActiveObject("Excel.Application");
    Excel.Workbooks objBooks;    
    Excel._Workbook objBook;
            
objBooks = objApp.Workbooks;    // Adds to the workbooks collection - objBooks.Count will now == 1

objBook = objBooks["Name of workbook"]; // No filename extension, just the name shown in the workbook window title bar