将datatable 保存为 Excel文件（高效率版本）

原文地址：https://www.cnblogs.com/dongh/p/6909611.html

using Microsoft.Office.Interop.Excel;
using System.Runtime.InteropServices;

[DllImport("User32.dll", CharSet = CharSet.Auto)]
public static extern int GetWindowThreadProcessId(IntPtr hwnd, out int pid);
//函数原型；DWORD GetWindowThreadProcessld(HWND hwnd，LPDWORD lpdwProcessld);
//参数：hWnd:窗口句柄
//参数：lpdwProcessld:接收进程标识的32位值的地址。如果这个参数不为NULL，GetWindwThreadProcessld将进程标识拷贝到这个32位值中，否则不拷贝
//返回值：返回值为创建窗口的线程标识。

//dt：从数据库读取的数据；file_name：保存路径；sheet_name：表单名称
private void DataTableToExcel(DataTable dt, string file_name, string sheet_name)
{
       Microsoft.Office.Interop.Excel.Application Myxls = new  Microsoft.Office.Interop.Excel.Application();
       Microsoft.Office.Interop.Excel.Workbook Mywkb = Myxls.Workbooks.Add();
       Microsoft.Office.Interop.Excel.Worksheet MySht = Mywkb.ActiveSheet;
       MySht.Name = sheet_name;
       Myxls.Visible = false;
       Myxls.DisplayAlerts = false;
       try
       {
              //写入表头
              object[] arrHeader = new object[dt.Columns.Count];
              for(int i = 0; i < dt.Columns.Count; i++)
              {
                     arrHeader[i] = dt.Columns[i].ColumnName;
              }
              MySht.Range[Mysht.Cells[1,1], MySht.Cells[1,dt.Columns.Count]].Value2 = arrHeader;
              //写入表体数据
              object[,] arrBody = new object[dt.Rows.Count, dt.Columns.Count];
              for(int i = 0; i < dt.Rows.Count; i++)
              {
                      for(int j = 0; j < dt.Columns.Count; j++)
                      {
                              arrBody[i,j] = dt.Rows[i][j].ToString();
                      }
              }
              MySht.Range[MySht.Cells[2,1], MySht.Cells[dt.Rows.Count + 1, dt.Columns.Count]].Value2 = arrBody;
              if(Mywkb != null)
              {
                      Mywkb.SaveAs(file_name);
                      Mywkb.Close(Type.Missing, Type.Missing, Type.Missing);
                      Mywkb = null;
              }
       }
       catch(Exception ex)
       {
               MessageBox.Show(ex.Message, "系统提示");
       }
       finally
       {
                //彻底关闭Excel进程
                if(Myxls != null)
                {
                       Myxls.Quit();
                       try
                       {
                              if(Myxls != null)
                              {
                                    int pid;
                                    GetWindowThreadProcessId(new IntPtr(Myxls.Hwnd), out pid);
                                    System.Diagnostics.Process p = System.Diagnostics.Process.GetProcessById(pid);
                                     p.Kill();
                              }
                       }
                       catch(Exception ex)
                       {
                              MessageBox.Show("结束当前EXCEL进程失败：" + ex.Message);
                       }
                       Myxls = null;
                }
                GC.Collect();
       }
}