有请高手帮忙—关于从DBGrid导入excel中出错。

Question

导出函数：
procedure Tfrmuq.CopyDbDataToExcel(target: TDbGrid);
var
   icount,jcount:integer;
   xlApp: variant;
   sheet:variant;
   temp:string;
   cnum:integer;
begin
   savedialog1.Filter:='Excel文件(*.xls)|*.xls';
  SaveDialog1.Options:=[ofShowHelp,ofEnableSizing];
  if SaveDialog1.Execute then
  begin
     Screen.Cursor:=crHourGlass;
     try
     if not VarIsEmpty(xlApp) then
     begin
          xlApp.DisplayAlerts:=false;
          xlApp.Quit;
          VarClear(xlApp);
     end;
     ///////////////////create excel object by ole
     try
        xlApp:=CreateOleObject('Excel.Application');
     except
        Screen.Cursor:=crDefault;
        exit;
     end;
     xlApp.WorkBooks.Add[XLWBatWorkSheet];
     xlApp.WorkBooks[1].WorkSheets[1].Name:='exlsheet';
     sheet:=xlApp.WorkBooks[1].WorkSheets['exlsheet'];     if not target.DataSource.DataSet.Active then
     begin
          Screen.Cursor:=crDefault;
          exit;
     end;
     target.DataSource.DataSet.First;
     cnum:=1;
     for icount:=0 to target.Columns.Count-1 do
          if target.Columns[icount].Visible=true then
            begin
            sheet.cells[1,cnum]:=target.Columns.Items[cnum-1].Title.Caption;
            inc(cnum);
            end;
     jcount:=2;
     while not target.DataSource.DataSet.Eof do
     begin
           cnum:=1;
           for icount:=0 to target.Columns.Count-1 do
           begin
            //  if icount=0 then
            //  begin
            if target.Columns[icount].Visible=true then
              begin
               temp:=target.Columns.Items[icount].Field.AsString;
               insert('''',temp,1);
               sheet.cells[jcount,cnum]:=temp;
               inc(cnum);
              end;
            //  end
             // else            //后面也可能有多位数字的字段
            //  sheet.cells[jcount,icount+1]:=target.Columns.Items[icount].Field.AsString;
          end;
          inc(jcount);
          target.DataSource.dataset.Next;     end;
     //begin
     sheet.SaveAs(SaveDialog1.FileName);
     application.MessageBox('数据导出成功！','提示信息',64+0);
     //end;
     xlApp.Quit;
     SaveDialog1.Options:=[ofOverwritePrompt,ofShowHelp,ofEnableSizing];
     finally
     Screen.Cursor:=crDefault;
     end;     
  end;
end;
出错提示：project project1.exe raised exception class EAccessviolation with message 'Access violation address 00000000.Read of address 00000000'.Process stopped.use step or Run to continue.请高手指点

Answer 1

function ExportToExcel(dbgrid:tdbgrid):boolean;
const
  xlNormal=-4143;
var
  i,j,k:integer;
  str,filename:string;
  excel:OleVariant;
  SavePlace: TBook;
  savedialog:tsavedialog;
  ProgressBar1:TProgressBar;
begin
  result:=false;
  filename:='';
  if not dbgrid.DataSource.DataSet.Active then
     begin
       application.MessageBox('数据集尚未打开！','错误',0);
       exit; 
     end;
  screen.Cursor:=crHourGlass;
  try
    excel:=CreateOleObject('Excel.Application');
    excel.workbooks.add;
  except
     screen.cursor:=crDefault;
    showmessage('无法调用Excel！');
    exit;
  end;
  savedialog:=tsavedialog.Create(nil);
  savedialog.Filter:='Excel文件(*.xls)|*.xls';
  if savedialog.Execute then
     begin
       if FileExists(savedialog.FileName) then
          try
            if application.messagebox('该文件已经存在，要覆盖吗？','询问',mb_yesno+mb_iconquestion)=idyes then
               DeleteFile(PChar(savedialog.FileName))
            else
               begin
                 Excel.Quit;
                 savedialog.free;
                  screen.cursor:=crDefault;
                 Exit;
               end;
          except
            Excel.Quit;
            savedialog.free;
             screen.cursor:=crDefault;
            Exit;
          end;
       filename:=savedialog.FileName;
     end;
  savedialog.free;
  if filename='' then
     begin
       result:=true;
       Excel.Quit;
       screen.cursor:=crDefault;
       exit;
     end;
  k:=0;
  for i:=0 to dbgrid.Columns.count-1 do
    begin
      if dbgrid.Columns.Items[i].Visible then
         begin
           //Excel.Columns[k+1].ColumnWidth:=dbgrid.Columns.Items[i].Title.Column.Width;
           excel.cells[1,k+1]:=dbgrid.Columns.Items[i].Title.Caption;
           inc(k);
         end;
    end;  dbgrid.DataSource.DataSet.DisableControls;
  saveplace:=dbgrid.DataSource.DataSet.GetBook;
  dbgrid.DataSource.dataset.First;
  i:=2;  ProgressBar1:=ProgressBarform(dbgrid.DataSource.DataSet.RecordCount);
  while not dbgrid.DataSource.dataset.Eof do
    begin
      k:=0;
      for j:=0 to dbgrid.Columns.count-1 do
        begin
          if dbgrid.Columns.Items[j].Visible then
             begin
               //excel.cells[i,k+1].NumberFormat:='@';
               if not dbgrid.DataSource.dataset.fieldbyname(dbgrid.Columns.Items[j].FieldName).isnull then
                  begin
                    str:=dbgrid.DataSource.dataset.fieldbyname(dbgrid.Columns.Items[j].FieldName).value;
                    Excel.Cells[i, k + 1] := Str;
                  end;
               inc(k);
             end
          else
             continue;
        end;
      inc(i);
      ProgressBar1.StepBy(1);
      dbgrid.DataSource.dataset.next;
    end;
  progressbar1.Parent.Free;  dbgrid.DataSource.dataset.GotoBook(SavePlace);
  dbgrid.DataSource.dataset.EnableControls;  try
    if copy(FileName,length(FileName)-3,4)<>'.xls' then
       FileName:=FileName+'.xls';
    Excel.ActiveWorkbook.SaveAs(FileName, xlNormal, '', '', False, False);
  except
    Excel.Quit;
    screen.cursor:=crDefault;
    exit;
  end;
  Excel.Visible := true;
  screen.cursor:=crDefault;
  Result := true;
end;

Answer 2

function ProgressBarform(max:integer):tProgressBar;
var
  ProgressBar1:tProgressBar;
  form:tform;
begin
  application.CreateForm(tform,form);
  form.Position:=poScreenCenter;
  form.BorderStyle:=bsnone;
  form.Height:=30;
  form.Width:=260;
  ProgressBar1:=tProgressBar.Create(form);
  ProgressBar1.Smooth:=true;
  ProgressBar1.Max:=max;
  ProgressBar1.Parent:=form;
  ProgressBar1.Height:=20;
  ProgressBar1.Width:=250;
  ProgressBar1.Left:=5;
  ProgressBar1.Top:=5;
  ProgressBar1.Step:=1;
  form.Show;
  result:=ProgressBar1;
end;

Answer 3

project project1.exe raised exception class EAccessviolation with message 'Access violation address 00000000.Read of address 00000000'.Process stopped.use step or Run to continue.谁能给解释解释这个错误，最好对应我的源程序

Answer 4

用我这个吧
不过记得要uses comctrls,db,dbgrids,comobj

Answer 5

function ProgressBarform(max:integer):tProgressBar;
这个函数是什么意思
请高手给我整个的这段程序unit  贴出来。

Answer 6

这个ProgressBarform函数放在ExportToExcel函数的前面就可以了这两个函数可以单独编译的

Answer 7

为什莫运行不了呀？？？---------------------lzf1010(深宇)