Base64编码的字符串与图片的转换 C#

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();
}

//图片 转为    base64编码的文本
private void button1_Click(object sender, EventArgs e)
{
OpenFileDialog dlg = new OpenFileDialog();
dlg.Title = "选择要转换的图片";
dlg.Filter = "Image files (*.jpg;*.bmp;*.gif)|*.jpg*.jpeg;*.gif;*.bmp|AllFiles (*.*)|*.*";
if (DialogResult.OK == dlg.ShowDialog())
{
ImgToBase64String(dlg.FileName);
}
}
//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.Title = "选择要转换的base64编码的文本";
dlg.Filter = "txt files|*.txt";
if (DialogResult.OK == dlg.ShowDialog())
{
Base64StringToImage(dlg.FileName);
}
}
//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.pictureBox1.Image = bmp;
MessageBox.Show("转换成功！");
}
catch (Exception ex)
{
MessageBox.Show("Base64StringToImage 转换失败/nException："+ex.Message);
}
}
}
}