将base64格式的字符串生成文件

using System;
using System.IO;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            string base64 = "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";
            byte[] bytes = Convert.FromBase64String(base64);
            using(FileStream fileStream = new FileStream("testFile", FileMode.Create))
            {
                using(BinaryWriter bw = new BinaryWriter(fileStream))
                {
                    bw.Write(bytes);
                }
            }
            Console.Read();
        }
    }
}