C# 将二进制数据转换成BASE64字符串的方法

//编码例子  System.IO.FileStream fs = System.IO.File.OpenRead("c://1.jpg");  byte[] dt = new byte[fs.Length];  fs.Read(dt, 0, (int)fs.Length);  fs.Close();  string s = Convert.ToBase64String(dt);  fs = System.IO.File.OpenWrite("c://1.b64");  dt = Encoding.Default.GetBytes(s);  fs.Write(dt, 0, dt.Length);  fs.Flush();  fs.Close();  //解码例子  System.IO.FileStream fs = System.IO.File.OpenRead("c://1.b64");  byte[] dt = new byte[fs.Length];  fs.Read(dt, 0, (int)fs.Length);  string s = Encoding.Default.GetString(dt);  dt = Convert.FromBase64String(s);  fs = System.IO.File.OpenWrite("c://2.jpg");  fs.Write(dt, 0, dt.Length);  fs.Close();