untiy I/O

public static class IOHelper
{
    public static bool IsFileExists(string fileName)  // 判断文件是否存在
    {
        return File.Exists(fileName);
    }

    public static bool IsDirectoryExists(string fileName)  // 判断文件夹是否存在
    {
        return Directory.Exists(fileName);
    }

    public static void CreateFile(string fileName,string content)  // 创建一个文本文件 .(路径,内容)
    {
        StreamWriter streamWriter = File.CreateText(fileName);
        streamWriter.Write(content);
        streamWriter.Close();
    }

    public static void CreateDirectory(string fileName)// 创建一个文件夹
    {    
        if(IsDirectoryExists (fileName))   //文件夹存在则返回
            return;
        Directory.CreateDirectory(fileName);
    }
}