C#判断字符串是否base64，及base64转换为Bitmap

来源：互联网发布：webdriver调用js 编辑：程序博客网时间：2024/06/06 00:04
using System;using System.Linq;using System.Reflection;using System.Text.RegularExpressions;using System.IO;using System.Drawing;namespace XTools{    public class Base64Utility    {        private static char[] base64CodeArray = new char[]        {            'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',            'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',            '0', '1', '2', '3', '4',  '5', '6', '7', '8', '9', '+', '/', '='        };        /// <summary>        /// 是否base64字符串        /// </summary>        /// <param name="base64Str">要判断的字符串</param>        /// <returns></returns>        public static bool IsBase64(string base64Str)        {            byte[] bytes = null;            return IsBase64(base64Str, out bytes);        }        /// <summary>        /// 是否base64字符串        /// </summary>        /// <param name="base64Str">要判断的字符串</param>        /// <param name="bytes">字符串转换成的字节数组</param>        /// <returns></returns>        public static bool IsBase64(string base64Str, out byte[] bytes)        {            //string strRegex = "^([A-Za-z0-9+/]{4})*([A-Za-z0-9+/]{4}|[A-Za-z0-9+/]{3}=|[A-Za-z0-9+/]{2}==)$";            bytes = null;            if (string.IsNullOrEmpty(base64Str))                return false;            else            {                if (base64Str.Contains(","))                    base64Str = base64Str.Split(',')[1];                if (base64Str.Length % 4 != 0)                    return false;                if (base64Str.Any(c => !base64CodeArray.Contains(c)))                    return false;            }            try            {                bytes = Convert.FromBase64String(base64Str);                return true;            }            catch (FormatException)            {                return false;            }        }        /// <summary>        /// 把base64字符串转换成Bitmap        /// </summary>        /// <param name="base64Str">要转换的base64字符串</param>        /// <returns></returns>        public static Bitmap Base64ToBitmap(string base64Str)        {            Bitmap bitmap = null;            byte[] bytes = null;            try            {                if (IsBase64(base64Str, out bytes))                {                    using (MemoryStream stream = new MemoryStream(bytes))                    {                        stream.Seek(0, SeekOrigin.Begin);//为了避免有时候流指针定位错误，显式定义一下指针位置                        bitmap = new Bitmap(stream);                    }                }            }            catch (Exception)            {                bitmap = null;            }            return bitmap;        }        /// <summary>        /// 根据base64字符串获取文件后缀（图片格式）        /// </summary>        /// <param name="base64Str">base64</param>        /// <returns></returns>        public static string GetSuffixFromBase64Str(string base64Str)        {            string suffix = string.Empty;            string prefix = "data:image/";            if (base64Str.StartsWith(prefix) && base64Str.Contains(";") && base64Str.Contains(","))            {                base64Str = base64Str.Split(';')[0];                suffix = base64Str.Substring(prefix.Length);            }            return suffix;        }    }}
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