Check Write Permission

确认程序是否对文件夹有写权限

public bool CheckWritePermissionOnDir(string path, bool checkUserAccountControl = false)
{
    bool writeAllow = false;
    bool writeDeny = false;
    bool administratorPermission = true;

    DirectorySecurity directorySecurity = Directory.GetAccessControl(path);
    if (directorySecurity==null)
    {
        return false;
    }
    
    AuthorizationRuleCollection authorizationRuleCollection = directorySecurity.GetAccessRules(true, true, typeof(NTAccount));
    //AuthorizationRuleCollection authorizationRuleCollection = directorySecurity.GetAccessRules(true, true, typeof(SecurityIdentifier));
    if (authorizationRuleCollection == null)
    {
        return false;
    }

    foreach (FileSystemAccessRule rule in authorizationRuleCollection)
    {
        if ((FileSystemRights.Write& rule.FileSystemRights) != FileSystemRights.Write)
        {
            continue;
        }
        if(rule.AccessControlType==AccessControlType.Allow)
        {
            writeAllow = true;
            if (rule.IdentityReference.Value=="BUILTIN\\Users" || rule.IdentityReference.Value == "NT AUTHORITY\\Authenticated Users")
            {
                administratorPermission = false;
            }
        }
        else if (rule.AccessControlType == AccessControlType.Deny)
        {
            writeDeny = true;
        }
    }
    if (checkUserAccountControl)
    {
        return writeAllow && !writeDeny && !administratorPermission;
    }
    else
    {
        return writeAllow && !writeDeny;
    }

}

FileStream

写入文件

using (FileStream DestinationStream = new FileStream(pathElogTextRegistryLocal, FileMode.Create))
{
    await stream.CopyToAsync(DestinationStream);
}

FileStream与StreamReader区别

FileStream类提供了在文件中读写字节的方法，但经常使用StreamReader或 StreamWriter执行这些功能。这是因为FileStream类操作的是字节和字节数组，而StreamReader类操作的是字符数据。因此FileStream类既可以对文本文件进行读写也可以对多媒体文件进行读写，多用于对大文件进行读写，且它对文件可进行分步读写，减小内存压力。而StreamReader和StreamWriter类多用于对小文件读写。

• FileStream操作字节，更适合大文件。
• StreamReader操作字符，更适合小文件。