//图片 转为    base64编码的文本

        private void button1_Click(object sender, EventArgs e)

        {

            OpenFileDialog dlg = new OpenFileDialog();

            dlg.Multiselect = true;

            dlg.Title = "选择要转换的图片";

            dlg.Filter = "Image files (*.jpg;*.bmp;*.gif;*.png)|*.jpg*.jpeg;*.gif;*.bmp|AllFiles (*.*)|*.*";

            if (DialogResult.OK == dlg.ShowDialog())

            {

                for (int i = 0; i < dlg.FileNames.Length; i++)

                {

                    ImgToBase64String(dlg.FileNames[i].ToString());

                }

            }

        }

        //图片 转为    base64编码的文本

        private void ImgToBase64String(string Imagefilename)

        {

            try

            {

                Bitmap bmp = new Bitmap(Imagefilename);

                this.pictureBox1.Image = bmp;

                FileStream fs = new FileStream(Imagefilename + ".txt", FileMode.Create);

                StreamWriter sw = new StreamWriter(fs);

                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();

                String strbaser64 = Convert.ToBase64String(arr);

                sw.Write(strbaser64);

                sw.Close();

                fs.Close();

               // MessageBox.Show("转换成功!");

            }

            catch (Exception ex)

            {

                MessageBox.Show("ImgToBase64String 转换失败\nException:" + ex.Message);

            }

        }

        //base64编码的文本 转为    图片

        private void button2_Click(object sender, EventArgs e)

        {

            OpenFileDialog dlg = new OpenFileDialog();

            dlg.Multiselect = true;

            dlg.Title = "选择要转换的base64编码的文本";

            dlg.Filter = "txt files|*.txt";

            if (DialogResult.OK == dlg.ShowDialog())

            {

                for (int i = 0; i < dlg.FileNames.Length; i++)

                {

                    Base64StringToImage(dlg.FileNames[i].ToString());

                }

            }

        }

        //base64编码的文本 转为    图片

        private void Base64StringToImage(string txtFileName)

        {

            try

            {

                FileStream ifs = new FileStream(txtFileName, FileMode.Open, FileAccess.Read);

                StreamReader sr = new StreamReader(ifs);

                String inputStr = sr.ReadToEnd();

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

                MemoryStream ms = new MemoryStream(arr);

                Bitmap bmp = new Bitmap(ms);

                //bmp.Save(txtFileName + ".jpg", System.Drawing.Imaging.ImageFormat.Jpeg);

                //bmp.Save(txtFileName + ".bmp", ImageFormat.Bmp);

                //bmp.Save(txtFileName + ".gif", ImageFormat.Gif);

                //bmp.Save(txtFileName + ".png", ImageFormat.Png);

                ms.Close();

                sr.Close();

                ifs.Close();

                this.pictureBox2.Image = bmp;

                if (File.Exists(txtFileName))

                {

                    File.Delete(txtFileName);

                }

                //MessageBox.Show("转换成功！");

            }

            catch (Exception ex)

            {

                MessageBox.Show("Base64StringToImage 转换失败\nException：" + ex.Message);

            }

        }

//

public class base64Test5 : IHttpHandler

    {

        public void ProcessRequest(HttpContext context)

        {

            context.Response.ContentType = "text/plain";

            HttpPostedFile hpf = context.Request.Files["fileName"];

            //将文件流写到byte数组中

            Stream stream = hpf.InputStream;

            byte[] bytes = new byte[stream.Length];

            stream.Read(bytes, 0, bytes.Length);

            //将byte数组转为base64String

            string base64String = Convert.ToBase64String(bytes);

            //将base64String 转为 byte数组

            byte[] byteArray = Convert.FromBase64String(base64String);

            string saveFileName = DateTime.Now.ToFileTime().ToString();

            string path = HttpContext.Current.Server.MapPath("../base/" + saveFileName + ".png");

            //使用文件流读取byte数组中的数据

            Stream s = new FileStream(path, FileMode.Append);

            s.Write(byteArray, 0, byteArray.Length);

            s.Close();

            context.Response.Write("Hello World");

        }

        public bool IsReusable

        {

            get

            {

                return false;

            }

        }

    }

//

Image fromImage = Image.FromFile( txtImg.Text );

MemoryStream stream = new MemoryStream();

fromImage.Save( stream, imgFormat[extension] );

txtString.Text = Convert.ToBase64String( stream.GetBuffer() );

MemoryStream stream = new MemoryStream( Convert.FromBase64String( txtString.Text ) );

bitmap img = new Bitmap( stream );

img.Save( txtImg.Text );

MessageBox.Show( "Completed!" ); 

using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Data;

using System.Drawing;

using System.IO;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

using System.Windows.Forms;

namespace Base64Demo

{

    public partial class Form1 : Form

    {

        private string base64Str;

        public Form1()

        {

            InitializeComponent();

        }

        private void button1_Click(object sender, EventArgs e)

        {

            //

            string path = textBox1.Text;  //界面上第一个文件路径

            string tempPath = textBox3.Text; //界面上第二个文件路径

            FileStream filestream = new FileStream(path, FileMode.Open);

            byte[] bt = new byte[filestream.Length];

            //调用read读取方法

            filestream.Read(bt, 0, bt.Length);

            this.base64Str = Convert.ToBase64String(bt);

            filestream.Close();

            //将Base64串写入临时文本文件

            if (File.Exists(tempPath))

            {

                File.Delete(tempPath);

            }

            FileStream fs = new FileStream(tempPath, FileMode.Create);

            byte[] data = System.Text.Encoding.Default.GetBytes(this.base64Str);

            //开始写入

            fs.Write(data, 0, data.Length);

            //清空缓冲区、关闭流

            fs.Flush();

            fs.Close();

        }

        private void button2_Click(object sender, EventArgs e)

        {

            string outPath = textBox2.Text;  //界面上第三个文件路径

            var contents = Convert.FromBase64String(this.base64Str);

            using (var fs = new FileStream(outPath, FileMode.Create, FileAccess.Write))

            {

                fs.Write(contents, 0, contents.Length);

                fs.Flush();

            }

        }

    }

}