C# Base64Helper

public static class base64helper
    {
        /// <summary>
        /// base64字符保存图片到本
        /// </summary>
        /// <param name="filepath">保存的图片完整路径</param>
        /// <param name="base64string">base64字符串</param>
        public static void base64saveimage(string filepath, string base64string)
        {
            try
            {
                //如果base64是通过http传过来的，要注意其中的%、，、空格等转换，c#规定base64的长度必须是4的倍数，有个别语言是2的倍数，补上==。
                base64string = base64string.trim().replace("%", "").replace(",", "").replace(" ", "+");
                if (base64string.length % 4 != 0)
                {
                    base64string += "==";
                }
                byte[] arr2 = convert.frombase64string(base64string);
                using (memorystream ms2 = new memorystream(arr2))
                {
                    system.drawing.bitmap bmp2 = new system.drawing.bitmap(ms2);
                    bmp2.save(filepath, system.drawing.imaging.imageformat.jpeg);
                    bmp2.dispose();
                }
            }
            catch (exception ex)
            {
                loghelper.writelog("图片保存异常：" + ex.tostring());
            }

        }

        public static string imgtobase64string(string imagefilename)
        {
            try
            {
                bitmap bmp = new bitmap(imagefilename);

                memorystream ms = new memorystream();
                bmp.save(ms, system.drawing.imaging.imageformat.jpeg);
                byte[] arr = new byte[ms.length];
                ms.position = 0;
                ms.read(arr, 0, (int)ms.length);
                ms.close();
                return convert.tobase64string(arr);
            }
            catch (exception ex)
            {
                loghelper.writelog("图片读取异常：" + ex.tostring());
                return null;
            }
        }

        public static string imagetobase64(string path)
        {
            byte[] bytes = getpicturedata(path);
            string base64 = convert.tobase64string(bytes);
            return base64;
        }

        public static bitmap base64toimage(string base64)
        {
            byte[] arr = convert.frombase64string(base64);
            memorystream ms = new memorystream(arr);
            bitmap bmp = new bitmap(ms);
            ms.close();
            return bmp;
        }

        public static byte[] getpicturedata(string imagepath)
        {
            filestream fs = new filestream(imagepath, filemode.open);
            byte[] bydata = new byte[fs.length];
            fs.read(bydata, 0, bydata.length);
            fs.close();
            return bydata;
        }
    }