解决asp.net中CF 3.5 Bitmap(Stream)未处理异常问题

www.111cn.net 更新:2012-01-17 编辑:drise1 来源:转载
本文章介绍了关于解决asp.net中CF 3.5 Bitmap(Stream)未处理异常问题 ,有在开发window mb的朋友如果碰到此类问题可以参考一下本文章哦。

VS2008开发环境,在进行.NET CF 3.5下的WM Socket编程时

Bitmap bmp = new Bitmap(Stream)处出现未处理异常

通过摸索,我发觉无论将对象如何设置为null和Dispose,这个问题依然存在。

究其原因,个人猜测是Bitmap实例化时本身就会打开MemoryStream流,所以再用MemoryStream就很容易内存泄露

因此强列建议,当和Bitmap一起合用时,用 FileStream或其它变通方法替代MemoryStream,并及时内存回收。

以下是使用参考示例:

主要功能是:拍照上传。

 代码如下 复制代码

View Code public class PhotoHelper
    {
        BaseForm _form;       //拍照上传窗体
        TextBox _txtFileName; //显示照片路径
        PictureBox _picPhoto; //显示照片缩略图
  
        public PhotoHelper(BaseForm form,TextBox txtFileName,PictureBox picPhoto)
        {
            _form = form;
            _txtFileName = txtFileName;
            _picPhoto = picPhoto;
            _picPhoto.Image = new Bitmap(300, 350);

        }

     
 

       #region 拍照逻辑
        public void TakePhoto()
        {
            //拍照-----------------------------         
            CameraCaptureDialog ccd = new CameraCaptureDialog();
            ccd.Mode = CameraCaptureMode.Still;
            ccd.Owner = _form;
            ccd.Title = "拍照";
            ccd.Resolution = new Size(1600, 1200);
            ccd.StillQuality = CameraCaptureStillQuality.Normal;

            if (ccd.ShowDialog() == DialogResult.OK)
            {
                //将拍好的以缩略图显示
                ImageChangedArgs args = new ImageChangedArgs(ccd.FileName);
                using (Graphics g = Graphics.FromImage(_picPhoto.Image))
                {

                    g.DrawImage(args.Image,
                        new Rectangle(0, 0, _picPhoto.Image.Width, _picPhoto.Image.Height),
                        new Rectangle(0, 0, args.Image.Width, args.Image.Height),
                        GraphicsUnit.Pixel);

                }
                args.Dispose();
                args = null;
               
                _txtFileName.Text = ccd.FileName;

            }
            ccd.Dispose();
            ccd = null;
        }        
      #endregion

      #region 照片上传逻辑

       public  void PhotoSave()
        {
            if (string.IsNullOrEmpty(_txtFileName.Text))
            {
                Global.ShowMsg("无照片可上传");
                return;
            }

            string prompt = "确认上传照片?";
            if (Global.ShowYesNoMsg(prompt) == DialogResult.No)
                return;

       
            //将照片转换为byte[]
            Byte[] b = FileToBytes(_txtFileName.Text);          

            #region todo 将Byte[] 通过webservice上传服务器,在此请加入自己代码
           // CommandAndTaskIdObj commandObj = _form.CommandAndTaskIdObj;
            //WsRmsg msg = Global.GetService().UpFile(commandObj.UserName, commandObj.CommandId ,commandObj.TaskId , b, _txtFileName.Text);
            //if (msg.Flag == 0)
            //{          
            //    b = null;
            //    throw new Exception(msg.Emsg);
            //}
            #endregion

            Global.ShowMsg("照片上传成功");
     
          
            _txtFileName.Text = string.Empty;          
            b = null;           
           
        }
        #endregion

        static byte[] FileToBytes(string sFilePath)
        {
            FileStream inFile = null;             
            try
            {
                byte[] binaryData;
                inFile = new FileStream(sFilePath, FileMode.Open, FileAccess.Read);
                binaryData = new Byte[inFile.Length];
                long bytesRead = inFile.Read(binaryData, 0, (int)inFile.Length);
                return binaryData;
            }
            catch (Exception ex)
            {
                throw ex;
            }
            finally
            {
                if (inFile != null)
                {
                    inFile.Close();
                    inFile.Dispose();
                }
                inFile = null;
            }
        }

        internal void PhotoDispose()
        {
            throw new NotImplementedException();
        }
    }

    public  class ImageChangedArgs : EventArgs, IDisposable
    {
        private Bitmap image;
        /// <summary>
        /// used to create the thumbnail
        /// </summary>
        private Stream stream;
        public ImageChangedArgs(string imageFilePath)
        {

            try
            {
                this.stream =   new FileStream(imageFilePath, FileMode.Open, FileAccess.Read);
                this.image = new Bitmap(this.stream);
            }
            catch(Exception ex)
            {
                this.image = null;
                if (this.stream != null)
                {
                    this.stream.Close();
                    this.stream = null;
                }
            }
        }

        public Bitmap Image
        {
            get
            {
                return this.image;
            }
        }

        public Stream Stream
        {
            get
            {
                return this.stream;
            }
        }

        #region IDisposable Members

        public void Dispose()
        {
            if (this.image != null)
                this.image.Dispose();
            this.image = null;
            if (this.stream != null)
            {
                this.stream.Close();
                this.stream.Dispose();
            }
            this.stream = null;
        }

        #endregion
    }

从上个例子可以看出,MemoryStream类基本上被FileStream替代。

当加载大的图片时,只要内存允许,就不会报Exception异常 

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