二进制图片格式转换

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 1  public static bool IsAllowedExtension(byte[] imgArray, FileExtension[] fileEx)

 2         {

 3             MemoryStream ms = new MemoryStream(imgArray);

 4             System.IO.BinaryReader br = new System.IO.BinaryReader(ms);

 5             string fileclass = "";

 6             byte buffer;

 7             try

 8             {

 9                 buffer = br.ReadByte();

10                 fileclass = buffer.ToString();

11                 buffer = br.ReadByte();

12                 fileclass += buffer.ToString();

13             }

14             catch

15             {

16             }

17             br.Close();

18             ms.Close();

19             foreach (FileExtension fe in fileEx)

20             {

21                 if (Int32.Parse(fileclass) == (int)fe)

22                     return true;

23             }

24             return false;

25         }

26         public  enum FileExtension

27         {

28             JPG = 255216,

29             GIF = 7173,

30             PNG = 13780,

31             SWF = 6787,

32             RAR = 8297,

33             ZIP = 8075,

34             _7Z = 55122,

35             XLS = 208207,

36             XLSX = 8075,

37             bmp = 6677

38         }

39 

40 调用

41  //判断下是否为gif

42                         if (IsAllowedExtension(buffer, new FileExtension[] { FileExtension.GIF,FileExtension.PNG,FileExtension.bmp }))

43                         {

44                             using (MemoryStream newstream = new MemoryStream())

45                             {

46                                 bitmap.Save(newstream, System.Drawing.Imaging.ImageFormat.Jpeg);

47                                 //

48                                 using (Bitmap newbitmap = new Bitmap(newstream, true))

49                                 {

50 }

51 }

52 }