Bitmap 引起内存不足问题解决。路过的朋友帮忙看下谢谢

需求：旧系统数据库 图片存的是进制。数据有13w条(历史原因)。需要把图片进制转换对应的图片保存到本地  新系统保存图片地址。。现在写一个小程序需要转换旧系统图片数据  winfrom

                    while (_isWhile)
                    {
                        sql= txtSql.Text.Replace(row, _nextRow).Replace(pagesize, txtRow.Text);
                        Logging.Instance.WriteEnqueue(null, sql);
                        var dt = GetImgData(sql);

                        if (dt == null)
                        {
                            //没有数据自动终止循环
                            _isWhile = false;
                            lblMsg.Text = "执行完成";
                            Logging.Instance.WriteEnqueue(null, lblMsg.Text);
                            return ;
                        }

                        for (int i = 0; i < dt.Rows.Count; i++)
                        {
                            //文件名
                            var imgName = dt.Rows[i][fileName];
                            
                            //图片进制
                            var stream = dt.Rows[i][fileStream];
                            if (string.IsNullOrEmpty(stream.ToString()))
                            {
                                Logging.Instance.WriteEnqueue(null, imgName + "对应列数据为空");
                                continue;
                            }

                            byte[] imagebytes = (byte[])stream;
                            var filename = path + "\\" + imgName + ".jpg";
                            //问题出现在这里 如何解决呢？
                            using (MemoryStream ms = new MemoryStream(imagebytes))
                            {
                                Bitmap bmpt = new Bitmap(ms);
                                bmpt.Save(filename, ImageFormat.Jpeg);
                            }
                            GC.Collect();
                            Thread.Sleep(20);
                            _indexSuccess++;
                        }

                        _whileCout++;
                        _nextRow = (_whileCout * int.Parse(txtRow.Text)).ToString();
                        if (!string.IsNullOrEmpty(txtRowStrar.Text))
                        {
                            _nextRow = (_whileCout * int.Parse(txtRow.Text)+int.Parse(txtRowStrar.Text)).ToString();  
                        }
                        lblMsg.Text = "当前循环次数"+ _whileCout;
                        GC.Collect();
                        Thread.Sleep(1000);
                    }

目前是分批读取数据 。但是这里

Bitmap 这块这样写我知道也有问题 不停的创建对象。 内存溢出。如何解决呢？

解决code：

            _indexSuccess = 0;
            BtnImg.Enabled = false;
            if (BtnImgVerification()) return;
            Logging.Instance.CreateFile(txtPath.Text);

            lblMsg.Text = "程序执行中.......";
            Task.Factory.StartNew(() =>
            {
                ExceptionsHelp.Instance.ExecuteVoidFunc(() =>
                {
                    var dr = DbHelperSql.ExecuteReader(txtSql.Text);
                    var ms = new MemoryStream();
                    while (dr.Read())
                    {
                        var imgName = dr[txtFileName.Text];
                        var stream = dr[txtFileStream.Text];

                        if (string.IsNullOrEmpty(stream.ToString()))
                        {
                            Logging.Instance.WriteEnqueue(null, imgName + "对应列数据为空");
                            continue;
                        }
                        byte[] imagebytes = (byte[])stream;
                        var filename = txtPath.Text + "\\" + imgName + ".jpg";
                        ms.Write(imagebytes, 0, imagebytes.Length);
                        using (FileStream fsWrite = new FileStream(filename, FileMode.Append))
                        {
                            fsWrite.Write(imagebytes, 0, imagebytes.Length);
                        };
                        ms.Position = 0;
                        _indexSuccess++;
                    }
                    ms.Dispose();
                    ms.Close();
                    dr.Close();
                    GC.Collect();
                    Logging.Instance.WriteEnqueue(null, _indexSuccess.ToString());
                    MessageBox.Show(_indexSuccess.ToString());

                }, "BtnImg_Click", () =>
                {
                    Method(BtnImg, x => x.Enabled = true);
                });
            });