Stream read error!Ole和Blob类型问题,在线等待，进着有分，不够再加

Question

试试在LoadFromStream之前先把流定位到开头，我经常犯这样的错误。
Memstream.Seek( 0, 0 ); 或
Memstream.Position := 0;

Answer 1

我用了下面的语句，可以了
    MemStream:=ADOQ.CreateBlobStream(ADOQblobfld,bmRead);
    MemStream.Position:=0;
    viewOleWord.LoadFromStream(Memstream);
但，多试几次就出问题了，Access violation at address 77A6... in module 'ole32.dll'. Read of address 00000000008.
用一个过程:
procedure TMainFrm.OleLoadFromBlobFld(Ole:TOleContainer;BlobFld:TBlobField);
var
  BlobStream: TBlobStream;
  MemStream: TMemoryStream;
begin
  MemStream:=TMemoryStream.Create;
  with ADOQ do
  begin
    BlobStream:=TBlobStream.Create(BlobFld, bmRead);
    try
      MemStream.CopyFrom(BlobStream,BlobStream.Size);
      Memstream.Position:=0;
      Ole.LoadFromStream(MemStream);
    finally
      BlobStream.Free;
      Memstream.Free;
    end;
  end;
end;
执行到    BlobStream:=TBlobStream.Create(BlobFld, bmRead);
时又出现： Invalid class typecast 错误，请各位大侠帮我。

Answer 2

在李唯的书中用Ado存取Blob自段是这样写的。能在TOleContainer中显示，也能够把他从数据库中取出存为文件：
unit Unit1;interfaceuses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, DB, ADODB, Grids, DBGrids, ExtCtrls, DBCtrls, StdCtrls, OleCtnrs;type
  TForm1 = class(TForm)
    ADOConnection1: TADOConnection;
    ADODataSet1: TADODataSet;
    DBNavigator1: TDBNavigator;
    DBGrid1: TDBGrid;
    DataSource1: TDataSource;
    OpenDialog1: TOpenDialog;
    OleContainer1: TOleContainer;
    Button1: TButton;
    Button2: TButton;
    Button3: TButton;
    SaveDialog1: TSaveDialog;
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
    procedure Button3Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;var
  Form1: TForm1;implementation{$R *.dfm}procedure TForm1.Button1Click(Sender: TObject);//把Blob对象存入数库
var
  sFileName:string;
  function BlobContentToString(const FileName:String):string;
   begin
    with TFileStream.Create(FileName,fmOpenRead) do
      try
       SetLength(Result,Size);
       Read(Pointer(Result)^,Size);
      finally
       Free;
      end;
   end;
begin
 if (OpenDialog1.Execute) then
  begin
   sFileName:=OpenDialog1.FileName;
   AdoDataSet1.Append;
   AdoDataSet1.FieldByName('名称').AsString:=ExtractFileName(sFileName);
   AdoDataSet1.FieldByName('对象').AsString:=BlobContentToString(sFileName);
   AdoDataSet1.Post;
  end;end;procedure TForm1.Button2Click(Sender: TObject);
//在TOleContainer中显示
var
 sFileName:String;
 BS:TAdoBlobStream;
begin
 BS:=TadoBlobStream.Create(TBlobField(AdodataSet1.FieldByName('对象')),bmRead);
 try
   sFileName:=ExtractFilePath(Application.ExeName);
   sFileName:=sFileName+AdoDataSet1.FieldByName('名称').asstring;
   BS.SaveToFile(sFileName);
   OleContainer1.CleanupInstance ;
   OleContainer1.CreateObjectFromFile(sFileName,false);
   OleContainer1.DoVerb(0);
 finally
   BS.Free;
 end;end;procedure TForm1.Button3Click(Sender: TObject);
//把Blob字段从数据库中导出存为文件，不过出错处理没有写好
//就是当出现存储对话框后，按取消按扭的是怎么取消
//存为文件没有写好，不好意思了
var
 sFileName:String;
 BS:TAdoBlobStream;
begin
 SaveDialog1.FileName:=AdoDataSet1.FieldByName('名称').asstring;
 if SaveDialog1.Execute then  BS:=TadoBlobStream.Create(TBlobField(AdodataSet1.FieldByName('对象')),bmRead);
  try
    sFileName:=SaveDialog1.FileName;
    //ShowMessage(sFileName);
    sFileName:=sFileName;//+AdoDataSet1.FieldByName('名称').asstring;
    BS.SaveToFile(sFileName);
   // OleContainer1.CleanupInstance ;
    //OleContainer1.CreateObjectFromFile(sFileName,false);
    //OleContainer1.DoVerb(0);
  finally
    BS.Free;
 end;//怎么判断存为按扭是确定还是取消end;end.

Answer 3

谢谢！我用的是ADO连接的，所以将 
BlobStream:=TBlobStream.Create(BlobFld, bmRead);
改为
BlobStream:=TADOBlobStream.Create(BlobFld, bmRead);
就好了。
但还是不稳定，用一会儿就出现
Access violation at address 77A6... in module 'ole32.dll'. Read of address 00....8

Answer 4

主要是我用了两个OleContainer，一个显示Word,另一个窗口里编辑,之间用了
FirstOle.Copy;
SecondOle.Paste;
传递数据，大多数情况下好的，偶尔就 Access violation at address 7D3A6...45 in module 'ole32.dll'. Read of address 00D3....A8
请高手们帮我解决。