/////  获取文件夹中的图片，批量转换
private void button1_Click(object sender, EventArgs e)
        {
            string strwjjs = textBox1.Text.Trim();
            string[] files1 = Directory.GetFiles(strwjjs);
            for (int i = 0; i < files1.Length; i++)
            {
                FileInfo file = new FileInfo(files1[i]);

              string strPicPath = string.Empty;
                if (textBox1.Text.Trim().EndsWith("\\"))
                {
                    strPicPath = textBox1.Text.Trim()  + file.Name;
                }
                else
                {
                    strPicPath = textBox1.Text.Trim() + "\\" + file.Name;
                }

              string strBase64=  ImageToBase64(strPicPath);


            }
            MessageBox.Show("保存成功");
        }

        /// <summary>
        /// 图片转base 64
        /// </summary>
        /// <param name="fileFullName"></param>
        /// <returns></returns>
        public string ImageToBase64(string fileFullName)
        {
            FileInfo file = new FileInfo(fileFullName);
            var stream = file.OpenRead();
            byte[] buffer = new byte[file.Length];
            //读取图片字节流
            stream.Read(buffer, 0, Convert.ToInt32(file.Length));
            //将base64字符串保存到base64.txt文件中
            StreamWriter sw = new StreamWriter("base64.txt", false, Encoding.UTF8);
            //将字节流转化成base64字符串
            //sw.Write(Convert.ToBase64String(buffer));
            sw.Close();
            return "data:image/jpeg;base64," + Convert.ToBase64String(buffer);
        }
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