為什么我用數据流把jpg檔導入數据庫后再把它導出來時它的大小就從几十ｋ變成几百ｋ了．

Question

為什么會這樣難道我什么地方沒有用對嗎．

Answer 1

存入
 Jpeg1 := TJPEGIMAGE.Create;
 jpeg1.CompressionQuality:=30;
 jpeg1.Compress;
// jpeg1.Height:=210;
// jpeg1.Width:=202; Jpeg1.LoadFromFile(opendialog1.FileName);
 query6.Close;
query6.SQL.Clear;
query6.SQL.Append('update cpxx set cpb10=:cp10');
query6.SQL.Append('where cpb1="'+edit9.text+'"');
 stringstream1 := TStringStream.create('');
 jpeg1.savetostream(stringstream1);
 query6.ParamByName('cp10').AsBlob:=stringstream1.datastring;
 query6.execsql;
// query2.Close;
 //query2.Open;
 image1.Picture.LoadFromFile(opendialog1.FileName);
stringstream1.free;
jpeg1.Free;
取出if  not Query2.FieldByName('bjds12').IsNull then
         begin
         try
         tempstream:=TStringStream.Create(' ');
         TBlobField(Query2.FieldByName('bjds12')).SaveToStream(tempstream);
         tempstream.Position:=0;
         JpegMap:=TJpegImage.Create;
         jpegmap.LoadFromStream(tempstream);
      //   blobstream:=TBlobStream.Create(TBlobField(Query2.FieldByName('bjds12')),bmRead);  //      blobstream.Size:=2000;
       //  JpegMap.LoadFromStream(blobstream);         dbImage1.Picture.BitMap.Assign(JpegMap);         dbimage1.CopyToClipboard;

Answer 2

错在，你取出时用了
dbImage1.Picture.BitMap.Assign(JpegMap);将其转换成了Bmp格式了。
当然大了。

Answer 3

GnuSoft(冠宇)老大!!!!!那這代碼應該怎樣寫呀。。我都快急死了