访问冲突在德尔福

在反序列化SQL查询我写的序列化下面的代码和形式反序列化，并对其内容德尔福访问冲突在德尔福

unit SerAndDeser; 

interface 

    uses Classes,MainForm,ListOfTables,DataOfTable,SerialForms,sysutils,ActiveX, DatabaseClasses, UnloadProcs; 

    procedure Ser(); 
    procedure Deser(); 
    function GetGUID(): string; 
    function DeleteSymbols(inputstr : string) : string; 
implementation 

    function GetGUID(): string; 
    var 
    GUID : TGUID; 
    begin 
    Result := ''; 
    if CoCreateGuid(GUID) = 0 then 
    Result := GUIDToString(GUID); 
    Result := StringReplace(Result, '{', '', []); 
    Result := StringReplace(Result, '}', '', []); 
    Result := StringReplace(Result, '-', '', [rfReplaceAll]); 
    end; 

    function DeleteSymbols(inputstr : string): string; 
    begin 
    Result := ''; 
    Result := StringReplace(inputstr, '-', '', [rfReplaceAll]); 
    Result := StringReplace(Result, ' ', '', [rfReplaceAll]); 
    Result := StringReplace(Result, '\', '', [rfReplaceAll]); 
    Result := StringReplace(Result, '/', '', [rfReplaceAll]); 
    end; 

    procedure Ser(); 

    var mForm : MainFormInfo; 
     tForm : TableFormInfo; 
     lForm : ListFormInfo; 
     tempFmtable : TfmTableData; 
     i,j : integer; 
     MyFileStream : TFileStream; 
     MyMemoryStream : TMemoryStream; 
     field : TableFieldInfo; 
    begin 
     try 
     mForm := nil; 

     mForm := MainFormInfo.Create(
     nil, 
     MainWindow.Left, 
     MainWindow.Top, 
     MainWindow.Height, 
     MainWindow.Width, 
     MainWindow.partofconnectstring, 
     MainWindow.dbname, 
     MainWindow.dbfilename); 
     mForm.Name := 'MainWindow'; 

     //table forms 
     try 
     tForm := nil; 
     field := nil; 

     for i := 0 to MainWindow.ComponentCount - 1 do 
      if (MainWindow.Components[i] is TfmTableData) then 
      begin 
       tempFmtable := MainWindow.Components[i] as TfmTableData; 
       tForm := TableFormInfo.Create(
       mForm, 
       tempFmtable.Left, 
       tempFmtable.Top, 
       tempFmtable.Height, 
       tempFmtable.Width, 
       tempFmtable.tname); 
       tForm.Name := tempFmtable.Name; 

       //fields 
       for j := 0 to tempFmtable.DBGrid1.Columns.Count - 1 do 
       begin 
       field := nil; 

       field := TableFieldInfo.Create(
        tForm, 
        tempFmtable.DBGrid1.Columns[j].FieldName, 
        tempFmtable.DBGrid1.Columns[j].Title.Caption, 
        tempFmtable.DBGrid1.Columns[j].Index, 
        tempFmtable.DBGrid1.Columns[j].Visible); 
        field.Name := DeleteSymbols(tempFmtable.DBGrid1.Columns[j].FieldName);{tempFmtable.DBGrid1.Columns[j].FieldName} {+ GetGUID;} 
       end; 
       // 

      end; 
     except 
     field.Free; 
     tForm.Free; 
     end; 
     // 

     //List form 
     try 
     lForm := nil; 
     lForm := ListFormInfo.Create(
      mForm, 
      fmListOfTables.Left, 
      fmListOfTables.Top, 
      fmListOfTables.Height, 
      fmListOfTables.Width); 
     lForm.Name := 'fmListOfTables'; 
     except 
     lForm.Free; 
     end; 
     // 

     //save 
     MyFileStream := nil; 
     MyMemoryStream := nil; 

     MyFileStream := TFileStream.Create('test.txt', fmCreate); 
     MyMemoryStream := TMemoryStream.Create; 
     MyMemoryStream.WriteComponent(mForm); 
     MyMemoryStream.Position := 0; 
     ObjectBinaryToText(MyMemoryStream,MyFileStream); 
     MainWindow.Panel1.DockManager.SaveToStream(MyFileStream); 
     // 

    finally 
     mForm.Free; 
     MyFileStream.Free; 
     MyMemoryStream.Free; 
    end; 
    end; 


    procedure Deser(); 

    var mForm : MainFormInfo; 
     tForm : TableFormInfo; 
     lForm : ListFormInfo; 
     tempFmtable : TfmTableData; 
     i,j : integer; 
     MyFileStream : TFileStream; 
     MyMemoryStream : TMemoryStream; 
     table : TTableSpec; 
     descr : string; 
     field : TableFieldInfo; 


    begin 
    try 
     //destroy environment 
     i := 0; 
     while (i <= MainWindow.ComponentCount - 1) do 
     begin 
     if MainWindow.Components[i] is TfmTableData then 
      try 
      tempFmTable := nil; 
      tempFmTable := MainWindow.Components[i] as TfmTableData; 
      tempFmTable.IBQuery1.Close; 
      tempFmtable.Free; 
      except 
      tempFmTable.Free; 
      end 
     else 
      inc(i); 
     end; 
     fmListOfTables.Free; 
     DBSchema.Free; 
     // 

     //read 
     mForm := nil; 
     MyFileStream := nil; 
     MyMemoryStream := nil; 

     mForm := MainFormInfo.Create(nil, -1, -1, -1, -1, MainWindow.partofconnectstring, MainWindow.dbname, MainWindow.dbfilename); 

     MyFileStream := TFileStream.Create('test.txt', fmOpenRead); 
     MyMemoryStream := TMemoryStream.Create; 
     ObjectTextToBinary(MyFileStream,MyMemoryStream); 
     MyMemoryStream.Position := 0; 
     MyMemoryStream.ReadComponent(mForm); 
     // 

     //go 
     UnloadProcs.ConnectToDatabase(MainWindow.partofconnectstring, MainWindow.SQLConnection1); 
     //UnloadProcs.CreateObjs(MainWindow.SQLConnection1, MainForm.DBSchema); 
     //fmListOfTables.Show; 

     MainWindow.Left := mForm.LeftValue; 
     MainWindow.Top := mForm.TopValue; 
     MainWindow.Height := mForm.HeightValue; 
     MainWindow.Width := mForm.WidthValue; 

     //list 
     i := 0; 
     while i <= mForm.ComponentCount - 1 do 
     begin 
     if mForm.Components[i] is ListFormInfo then 
      try 
      lForm := nil; 
      lForm := mForm.Components[i] as ListFormInfo; 
      fmListOfTables.Left := lForm.LeftValue; 
      fmListOfTables.Top := lForm.TopValue; 
      fmListOfTables.Height := lForm.HeightValue; 
      fmListOfTables.Width := lForm.WidthValue; 
      fmListOfTables.Show; 
      inc(i); 
      finally 
      lForm.Free; 
      end 
     else 
      inc(i); 
     end; 
     // 

     //fmListOfTables.Show; 
     //tables 
     for j := 0 to mForm.ComponentCount - 1 do 
     if mForm.Components[j] is TableFormInfo then 
      try 
      table := nil; 
      tempFmtable := nil; 
      tForm := nil; 

      tForm := mForm.Components[j] as TableFormInfo; 

      table := TTableSpec(DBSchema.Tables.FindComponent(tForm.Table)); 
      tempFmtable := TfmTableData.Create(MainWindow); 
      tempFmtable.Name := tForm.Name; 
      tempFmtable.tname := tForm.Table; 
      //tempFmtable.Caption := Utf8ToAnsi(table.Description); 
      tempFmtable.Left := tForm.LeftValue; 
      tempFmtable.Top := tForm.TopValue; 
      tempFmtable.Height := tForm.HeightValue; 
      tempFmtable.Width := tForm.WidthValue; 

      tempFmTable.IBQuery1.SQL.Clear; 
      tempFmtable.IBQuery1.SQL.Add('select * from ' + table.Name); 
      tempFmtable.IBQuery1.Open; 

      i := 0; 
      while i <= tForm.ComponentCount - 1 do 
       if tForm.Components[i] is TableFieldInfo then 
       begin 
       field := nil; 

       field := tForm.Components[i] as TableFieldInfo; 
       tempFmtable.DBGrid1.Columns[i].FieldName := field.FieldNameValue; 
       tempFmtable.DBGrid1.Columns[i].Title.Caption := field.DescriptionValue; 
       tempFmtable.DBGrid1.Columns[i].Index := field.IndexValue; 
       tempFmtable.DBGrid1.Columns[i].Visible := field.VisibleValue; 
       //tempFmtable.CheckListBox1.Items.Add(field.Description); 
       //tempFmtable.CheckListBox1.Checked[i] := field.Visible; 
       inc(i); 
       end 
       else 
       inc(i); 

      {for i := 0 to table.Fields.ComponentCount - 1 do 
      begin 
       descr := Utf8ToAnsi(((table.Fields.Components[i]) as TFieldSpec).Description); 
       tempFmtable.CheckListBox1.Items.Add(descr); 
       tempFmtable.DBGrid1.Columns[i].Title.Caption := descr; 
       tempFmtable.CheckListBox1.Checked[i] := true; 
      end; } 

      tempFmtable.Show; 


      except 
      tempFmtable.Free; 
      tForm.Free; 
      table.Free; 
      end; 
     // 

     //dock 
     MainWindow.Panel1.DockManager.BeginUpdate; 
     MainWindow.Panel1.DockManager.LoadFromStream(MyFileStream); 
     MainWindow.Panel1.DockManager.ResetBounds(TRUE); 
     MainWindow.Panel1.DockManager.EndUpdate; 


     // 
    finally 
     MyFileStream.Free; 
     MyMemoryStream.Free; 
    end; 

    end; 

end.

调试时我发现给出了

'Project GUI.exe raised exception class $C0000005 with message 'access violation at 0x00821dae: read of address 0x00000044'.

异常在线

tempFmtable.IBQuery1.SQL.Add('select * from ' + table.Name);

在以下代码块中从a代码是较高

//tables 
    for j := 0 to mForm.ComponentCount - 1 do 
    if mForm.Components[j] is TableFormInfo then 
     try 
     table := nil; 
     tempFmtable := nil; 
     tForm := nil; 

     tForm := mForm.Components[j] as TableFormInfo; 

     table := TTableSpec(DBSchema.Tables.FindComponent(tForm.Table)); 
     tempFmtable := TfmTableData.Create(MainWindow); 
     tempFmtable.Name := tForm.Name; 
     tempFmtable.tname := tForm.Table; 
     //tempFmtable.Caption := Utf8ToAnsi(table.Description); 
     tempFmtable.Left := tForm.LeftValue; 
     tempFmtable.Top := tForm.TopValue; 
     tempFmtable.Height := tForm.HeightValue; 
     tempFmtable.Width := tForm.WidthValue; 

     tempFmTable.IBQuery1.SQL.Clear; 
     tempFmtable.IBQuery1.SQL.Add('select * from ' + table.Name); 
     tempFmtable.IBQuery1.Open; 

     i := 0; 
     while i <= tForm.ComponentCount - 1 do 
      if tForm.Components[i] is TableFieldInfo then 
      begin 
      field := nil; 
      //tempFmtable.Show; 
      field := tForm.Components[i] as TableFieldInfo; 
      tempFmtable.DBGrid1.Columns[i].FieldName := field.FieldNameValue; 
      tempFmtable.DBGrid1.Columns[i].Title.Caption := field.DescriptionValue; 
      tempFmtable.DBGrid1.Columns[i].Index := field.IndexValue; 
      tempFmtable.DBGrid1.Columns[i].Visible := field.VisibleValue; 
      //tempFmtable.CheckListBox1.Items.Add(field.Description); 
      //tempFmtable.CheckListBox1.Checked[i] := field.Visible; 
      //tempFmtable.Show; 
      inc(i); 
      end 
      else 
      inc(i); 

     {for i := 0 to table.Fields.ComponentCount - 1 do 
     begin 
      descr := Utf8ToAnsi(((table.Fields.Components[i]) as TFieldSpec).Description); 
      tempFmtable.CheckListBox1.Items.Add(descr); 
      tempFmtable.DBGrid1.Columns[i].Title.Caption := descr; 
      tempFmtable.CheckListBox1.Checked[i] := true; 
     end; } 

     tempFmtable.Show; 


     except 
     tempFmtable.Free; 
     tForm.Free; 
     table.Free; 
     end;

来源

2012-12-15 user1851132

检查'table'变量是否不为零。 – RRUZ

是什么问题？减少代码。并告诉我们错误信息等，并提出具体问题！ –

@DavidHeffernan我显示消息错误。 – user1851132

失败行是：这种线路运行

tempFmtable.IBQuery1.SQL.Add('select * from ' + table.Name);

之前您分配table这样的：

table := TTableSpec(DBSchema.Tables.FindComponent(tForm.Table));

这似乎是FindComponent返回nil。

正如我确信你知道的，你必须有一个有效的对象实例来调用方法，访问字段和属性等。你的代码应该检查这个条件并作出相应的响应。

你可以在调试器中很容易地看到这一切。调试器将在该行中断，当你检查变量时，它会告诉你table是nil。然后，你必须查看代码并找出原因。我建议你花一些时间来提高调试技能，并学习如何使用可用的工具。

来源

2012-12-15 16:22:07

访问冲突在德尔福

回答

相关问题