public ActionResult Injpg(string base64str ) {  

　　　　　　　　string data=base64str//要处理下字符串 ,之前的要截取掉 不然会报错

            byte[] arr = Convert.FromBase64String(data);

            using (MemoryStream ms = new MemoryStream(arr))

            {

                Bitmap bmp = new Bitmap(ms);

                string p = "/text.jpg";

                var w = Server.MapPath(p);

                bmp.Save(w, System.Drawing.Imaging.ImageFormat.Jpeg);

                //bmp.Save(@"d:\"test.bmp", ImageFormat.Bmp);

                //bmp.Save(@"d:\"test.gif", ImageFormat.Gif);

                //bmp.Save(@"d:\"test.png", ImageFormat.Png);

                ms.Close();

                return Content(p);

            }

｝