delphi - Windows目录定义

Question

我有一个应用程序可以使用 Windows\System32\drivers\etc 文件夹中的 HOSTS 文件。但是，我不想将路径硬编码到 C:\Windows\System32，因为 Windows 可能未安装在驱动器 C: 上。

我尝试使用%WinDir%\system32\drivers\etc\hosts，但是当它在我的代码中的变量中使用时，它不会被扩展。

如何使用 %WinDir%\system32\drivers\etc\hosts 作为 hosts 文件的路径，这样我就不必对路径？

另一个问题是，在成功编译后，我收到了一个警告:

[DCC Warning] ApplicationWizard01.pas(67): W1002 Symbol 'TFileAttributes' is specific to a platform.

代码显示在答案here中

这是我的新代码:

unit KoushikHalder01;

interface

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Vcl.Buttons, Vcl.ExtCtrls,
  Vcl.ComCtrls;
type
  TForm01 = class(TForm)
    Label01: TLabel;
    Edit01: TEdit;
    Edit02: TEdit;
    BitBtn01: TBitBtn;
    BitBtn02: TBitBtn;
    procedure FormCreate(Sender: TObject);
    procedure FormClose(Sender: TObject; var Action: TCloseAction);
    procedure FormShow(Sender: TObject);
    procedure FormHide(Sender: TObject);
    procedure BitBtn01MouseEnter(Sender: TObject);
    procedure BitBtn02MouseEnter(Sender: TObject);
    procedure BitBtn01MouseDown(Sender: TObject; Button: TMouseButton;
      Shift: TShiftState; X, Y: Integer);
    procedure BitBtn02MouseDown(Sender: TObject; Button: TMouseButton;
      Shift: TShiftState; X, Y: Integer);
    procedure BitBtn01MouseLeave(Sender: TObject);
    procedure BitBtn02MouseLeave(Sender: TObject);
    procedure BitBtn02Click(Sender: TObject);
    procedure BitBtn01Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form01: TForm01;

implementation

{$R *.dfm}

uses System.IOUtils;

procedure TForm01.BitBtn01Click(Sender: TObject);
function GetSysDir: string;
function IncludeTrailingPathDelimiter(const S: string): string;
var
  Attributes: TFileAttributes;
  SL: TStringList;
  Idx: Integer;
  Buffer: array[0..MAX_PATH] of Char;
  PathAndFileName : String;
begin
   GetSystemDirectory(Buffer, MAX_PATH - 1);
   SetLength(Result, StrLen(Buffer));
   Result := Buffer;
   PathAndFileName := CheckTrailingPathDelimiter(GetSysDir) + 'drivers\etc\hosts`;
   Attributes := [];
   TFile.SetAttributes('PathAndFileName', Attributes);
   SL := TStringList.Create;
   try
      SL.LoadFromFile('PathAndFileName');

     if
        SL.IndexOf('10.220.70.34    VIRTSDP25') <> -1
     then
        begin
        Edit02.Font.Color := clRed;
        Edit02.Text := 'Your Host File Has Already Been Modified Successfully.';
        end;
     if
        SL.IndexOf('10.220.70.34    VIRTSDP25') = -1
     then
        begin
        SL.Add('10.220.70.34    VIRTSDP25');
        Edit02.Font.Color := clGreen;
        Edit02.Text := 'Your Host File Has Been Modified Successfully.';
        end;
     if
        SL.IndexOf('10.220.70.32    BSNLESDP25A') = -1
     then
        SL.Add('10.220.70.32    BSNLESDP25A');
     if
        SL.IndexOf('10.220.70.33    BSNLESDP25B') = -1
     then
        SL.Add('10.220.70.33    BSNLESDP25B');
     if
        SL.IndexOf('10.220.70.34    VIRTBSNLESDP25') = -1
     then
        SL.Add('10.220.70.34    VIRTBSNLESDP25');
     if
        SL.IndexOf('10.220.70.34    KOSDPTwentyfive.bsnl.in.net') = -1
     then
        SL.Add('10.220.70.34    KOSDPTwentyfive.bsnl.in.net');
     if
        SL.IndexOf('10.220.70.34    KOSDPTwentyfive.bsnl.net.in') = -1
     then
        begin
           SL.Add('10.220.70.34 KOSDPTwentyfive.bsnl.net.in');
           SL.SaveToFile('PathAndFileName');
        end;
     finally
       SL.Free;
   end;
    Include(Attributes, TFileAttribute.faSystem);
    Include(Attributes, TFileAttribute.faReadOnly);
    TFile.SetAttributes('PathAndFileName', Attributes);
end;

Answer 1

不要使用%Windir%\System32。使用专门设计的 Windows API 函数来查找该文件夹 GetSystemDirectory 。它是在Windows单元中定义的；这是一个快速包装器(未在 XE2 上测试，但适用于 XE):

由于您对我之前的答案有疑问，这里有一个完整编译的代码副本(我注释掉了您对 Edit02 的引用，因此您需要取消注释它们；其他所有内容都会编译与 XE2 下一样好:

uses 
  System.IOUtils;

function GetSysDir: string;
var
  Buffer: array[0..MAX_PATH] of Char;
begin
   GetSystemDirectory(Buffer, MAX_PATH - 1);
   SetLength(Result, StrLen(Buffer));
   Result := Buffer;
end;

{$WARN SYMBOL_PLATFORM OFF}
procedure TForm2.Button1Click(Sender: TObject);
var
  Attributes: TFileAttributes;
  SL: TStringList;
  Idx: Integer;
  PathAndFileName : String;
begin
   PathAndFileName := IncludeTrailingPathDelimiter(GetSysDir) + 'drivers\etc\hosts';
   Attributes := [];
   TFile.SetAttributes(PathAndFileName, Attributes);
   SL := TStringList.Create;
   try
     SL.LoadFromFile(PathAndFileName);

     if SL.IndexOf('10.220.70.34    VIRTSDP25') <> -1 then
     begin
       //Edit02.Font.Color := clRed;
       //Edit02.Text := 'Your Host File Has Already Been Modified Successfully.';
     end;

     if SL.IndexOf('10.220.70.34    VIRTSDP25') = -1 then
     begin
       SL.Add('10.220.70.34    VIRTSDP25');
       //Edit02.Font.Color := clGreen;
       //Edit02.Text := 'Your Host File Has Been Modified Successfully.';
     end;

     if SL.IndexOf('10.220.70.32    BSNLESDP25A') = -1 then
       SL.Add('10.220.70.32    BSNLESDP25A');
     if SL.IndexOf('10.220.70.33    BSNLESDP25B') = -1 then
       SL.Add('10.220.70.33    BSNLESDP25B');
     if SL.IndexOf('10.220.70.34    VIRTBSNLESDP25') = -1 then
       SL.Add('10.220.70.34    VIRTBSNLESDP25');
     if SL.IndexOf('10.220.70.34    KOSDPTwentyfive.bsnl.in.net') = -1 then
       SL.Add('10.220.70.34    KOSDPTwentyfive.bsnl.in.net');
     if SL.IndexOf('10.220.70.34    KOSDPTwentyfive.bsnl.net.in') = -1 then
       SL.Add('10.220.70.34 KOSDPTwentyfive.bsnl.net.in');
     SL.SaveToFile(PathAndFileName);
   finally
       SL.Free;
   end;
    Include(Attributes, TFileAttribute.faSystem);
    Include(Attributes, TFileAttribute.faReadOnly);
    TFile.SetAttributes(PathAndFileName, Attributes);
end;
{$WARN SYMBOL_PLATFORM ON}