从网络中获取图片显示到Image控件并保存到磁盘

一、从网络中获取图片信息：

   /// <summary>
         /// 获取图片
         /// </summary>
         /// <param name="url">Url</param>
         /// <returns>BitmapImage</returns>
         public BitmapImage GetImage(string url)
         {
             BitmapImage image=null;
             try
             {
                 image = new BitmapImage();
                 long fileLength = ;
                 //从url指定的网络地址获取图片信息
                 WebRequest webReq = WebRequest.Create(url);
                 WebResponse webRes = webReq.GetResponse();
                 fileLength = webRes.ContentLength;
                 Stream srm = webRes.GetResponseStream();
                 byte[] bufferbyte = new byte[fileLength];
                 int allByte = (int) bufferbyte.Length;
                 int startByte = ;
                 while (fileLength > )
                 {
                     int downByte = srm.Read(bufferbyte, startByte, allByte);
                     if (downByte == )
                     {
                         break;
                     }
                     startByte += downByte;
                     allByte -= downByte;
                 }
                 //以流的形式初始化图片
                 image.BeginInit();
                 image.StreamSource = new MemoryStream(bufferbyte);
                 image.EndInit();
                 srm.Close();
                 webRes.Close();
             }
             catch (Exception)
             {
                 Console.WriteLine("获取图片信息失败");
             }
             return image;
         }

二、在Image控件中显示获取到的图片

   public void ShowImage(BitmapImage img)
         {
             image.Source = img;
             image.Width = img.PixelWidth;
             image.Height = img.PixelHeight;
         }

image是Image控件

三、保存Image到磁盘

  /// <summary>
         /// 保存图片到磁盘
         /// </summary>
         /// <param name="img"></param>
         public void SaveImage(Image img)
         {
             //img为Image控件
             BitmapSource bsrc = (BitmapSource)img.Source;
             //保存文件对话框
             SaveFileDialog sf = new SaveFileDialog();
             //设定默认保存类型为Png
             sf.DefaultExt = ".png";
             //指定用户只能下载jpg和png格式的图片
             sf.Filter = "JPG 图片 (*.jpg)|*.jpg|PNG 图片 (*.png)|*.png";
             if (sf.ShowDialog() == true)
             {
                 PngBitmapEncoder pngE = new PngBitmapEncoder();
                 pngE.Frames.Add(BitmapFrame.Create(bsrc));
                 using (Stream stream = File.Create(sf.FileName))
                 {
                     pngE.Save(stream);
                 }
             }
         }