微信图片解决方法-windows版的dat文件

 public string decodeImg(string filepath)
        {
            Dictionary<string, byte[]> headers = new Dictionary<string, byte[]>
            {
                { "jpg", new byte[]{ 0xff, 0xd8 }},
                { "png", new byte[]{ 0x89, 0x50 }},
                { "gif", new byte[]{ 0x47, 0x49 }},
            };
            for (int i = 0; i < 10; i++)
            {
                try
                {
                    byte[] buf = File.ReadAllBytes(filepath);
                    foreach (string encoding in headers.Keys)
                    {
                        byte header_code = headers[encoding][0];
                        byte check_code = headers[encoding][1];
                        byte magic = do_magic(header_code, buf);
                        byte code = (byte)(buf[1] ^ magic);
                        if (check_code == code)
                        {
                            byte[] outbytes = decode(magic, buf);
                            string outpath = filepath.Replace("dat", encoding);
                            File.WriteAllBytes(outpath, outbytes);
                            return outpath;
                        }
                    }
                    break;
                }
                catch (FileNotFoundException ex)
                {
                    Thread.Sleep(1000);
                }
            }
            return null;
        }

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