Base64編碼的字符串與圖片的轉換

using System;  
using System.Collections.Generic;  
using System.ComponentModel;  
using System.Data;  
using System.Drawing;  
using System.Text;  
using System.Windows.Forms;  
using System.IO;  
using System.Drawing.Imaging;  
 
namespace base64_img  
{  
    public partial class Form1 : Form  
    {  
        public Form1()  
        {  
            InitializeComponent();  
        }  
 
        //圖片 轉為    base64編碼的文本  
        private void button1_Click(object sender, EventArgs e)  
        {  
            OpenFileDialog dlg = new OpenFileDialog();  
            dlg.Title = "選擇要轉換的圖片";  
            dlg.Filter = "Image files (*.jpg;*.bmp;*.gif)|*.jpg*.jpeg;*.gif;*.bmp|AllFiles (*.*)|*.*";  
            if (DialogResult.OK == dlg.ShowDialog())  
            {  
                ImgToBase64String(dlg.FileName);  
            }  
        }  
        //圖片 轉為    base64編碼的文本  
        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("轉換成功!");  
            }  
            catch (Exception ex)  
            {  
                MessageBox.Show("ImgToBase64String 轉換失敗 Exception:" + ex.Message);  
            }  
        }  
 
        //base64編碼的文本 轉為    圖片  
        private void button2_Click(object sender, EventArgs e)  
        {  
            OpenFileDialog dlg = new OpenFileDialog();  
            dlg.Title = "選擇要轉換的base64編碼的文本";  
            dlg.Filter = "txt files|*.txt";  
            if (DialogResult.OK == dlg.ShowDialog())  
            {  
                Base64StringToImage(dlg.FileName);  
            }  
        }  
        //base64編碼的文本 轉為    圖片  
        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);  
             &