Delphi 如何实现软件自动升级的功能

unit Main; 
 
interface 
 
uses 
 Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms, 
 Dialogs, StdCtrls, IdHTTP, IdBaseComponent, IdComponent, IdTCPConnection, 
 IdTCPClient, IdFTP, ComCtrls, ExtCtrls,IniFiles,ShellAPI, jpeg; 
 
type 
 TfrmMain = class(TForm) 
  IdFTP1: TIdFTP; 
  IdHTTP1: TIdHTTP; 
  ProgressBar1: TProgressBar; 
  GroupBox1: TGroupBox; 
  ld_host: TLabeledEdit; 
  ld_username: TLabeledEdit; 
  ld_psw: TLabeledEdit; 
  ld_port: TLabeledEdit; 
  Label1: TLabel; 
  cb_mode: TComboBox; 
  ProgressBar2: TProgressBar; 
  Label3: TLabel; 
  list_file: TListView; 
  Label4: TLabel; 
  procedure IdFTP1Work(Sender: TObject; AWorkMode: TWorkMode; 
   const AWorkCount: Integer); 
  procedure IdFTP1WorkEnd(Sender: TObject; AWorkMode: TWorkMode); 
  procedure FormCreate(Sender: TObject); private 
  { Private declarations } 
  FSize:Integer; 
  FPath: string; 
  FExePath: string; 
  FInitPath: string; 
  FIniFile:TIniFile; 
  FHandle:HWND; 
  FMainExe:string; 
  FParam: string; 
 
  procedure CheckUpdateList; 
  function ConnectFTP:Boolean; 
  procedure DownLoadFile; 
  procedure LoadIni; 
  procedure SaveIni; 
 public 
  { Public declarations } 
 end; 
 
var 
 frmMain: TfrmMain; 
 
implementation 
uses 
 Flash; 
{$R *.dfm} 
//下载进度 
procedure TfrmMain.IdFTP1Work(Sender: TObject; AWorkMode: TWorkMode; 
 const AWorkCount: Integer); 
begin 
 ProgressBar1.Position := AWorkCount; 
 Application.ProcessMessages; 
end; 
 
procedure TfrmMain.IdFTP1WorkEnd(Sender: TObject; AWorkMode: TWorkMode); 
begin 
 ProgressBar1.Position := 0; 
 ProgressBar2.StepBy(1); 
end; 
 
procedure TfrmMain.FormCreate(Sender: TObject); 
var 
 frm: TfrmFlash; 
begin 
 Self.Visible := False; 
 //闪屏，可以不加 
 frm := TfrmFlash.Create(nil); 
 frm.Show; 
 Application.ProcessMessages; 
 FExePath := ExtractFilePath(Application.ExeName); 
 FIniFile := TIniFile.Create(FExePath+'ftp.ini'); 
 //加载ini信息，就是主机和端口之类的信息 
 LoadIni; 
 try 
  ConnectFTP; 
  CheckUpdateList; 
  Self.Visible := True; 
  Application.ProcessMessages; 
  DownLoadFile; 
 finally 
   
  FreeAndNil(frm); 
  IdFTP1.Quit; 
  FParam := StringReplace(FParam,'{app}',FExePath,[rfReplaceAll]); 
//更新完毕后，启动主程序，并传入命令行参数 
  ShellExecute(Handle,'open',PChar(FExePath+FMainExe),PChar(FParam),nil,SW_NORMAL); 
  Application.Terminate; 
 end; 
end; 
 
//检查更新列表 
procedure TfrmMain.CheckUpdateList; 
var 
 oldFile,newFile:TStringList; 
 i,ver,index:Integer; 
 itemstr,itempath: string; 
 item:TListItem; 
begin 
 oldFile := TStringList.Create; 
 newFile := TStringList.Create; 
 try 
  list_file.Clear; 
  //先下载服务器上的update.ini文件，存到本地update_new.ini 
  IdFTP1.Get('update.ini',FExePath+'update_new.ini',True); 
  if FileExists(FExePath + 'update.ini') = False then Exit; 
  oldFile.LoadFromFile(FExePath + 'update.ini'); 
  newFile.LoadFromFile(FExePath + 'update_new.ini'); 
  itempath := ''; 
  //下面开始比较两个list，如果newFile的版本号大于oldFile的版本号或者oldFile中没有的都表示要更新的 
  for i := 0 to newFile.Count - 1 do 
  begin 
   itemstr := newFile.Strings[i]; 
   if itemstr = '' then Continue; 
   if itemstr[1] = '[' then 
   begin 
    itempath := Copy(itemstr,2,Length(itemstr)-2); 
    //如果是根目录 
    if itempath = 'root' then 
     itempath := '/'; 
    Continue; 
   end; 
   itemstr := newFile.Names[i]; 
   index := oldFile.IndexOfName(itemstr); 
   if index = - 1 then 
   begin 
    item := list_file.Items.Add; 
    item.Caption := itemstr; 
    item.SubItems.Add(itempath) 
   end 
   else 
   begin 
    ver := StrToIntDef(newFile.Values[itemstr],0); 
    if ver > StrToIntDef(oldFile.Values[itemstr],0) then 
    begin 
     item := list_file.Items.Add; 
     item.Caption := itemstr; 
     item.SubItems.Add(itempath); 
    end; 
   end; 
  end; 
  if list_file.Items.Count = 0 then Application.Terminate; 
 finally 
  oldFile.Free; 
  newFile.Free; 
 end; 
end; 
 
function TfrmMain.ConnectFTP: Boolean; 
begin 
 Result := False; 
 try 
 IdFTP1.Host := ld_host.Text; 
 IdFTP1.Port := StrToIntDef(ld_port.Text,21); 
 IdFTP1.Username := ld_username.Text; 
 IdFTP1.Password := ld_psw.Text; 
 IdFTP1.Connect; 
 IdFTP1.Passive := cb_mode.ItemIndex = 1; 
 FInitPath := IdFTP1.RetrieveCurrentDir; 
 Result := IdFTP1.Connected; 
 except 
  Result := False; 
 end; 
end; 
 
//下载文件更新 
procedure TfrmMain.DownLoadFile; 
var 
 i:Integer; 
 path:string; 
 s1,s2:String; 
begin 
 ProgressBar2.Max := list_file.Items.Count; 
 ProgressBar2.Position := 0; 
 FIniFile.EraseSection('error'); 
 for i := 0 to list_file.Items.Count - 1 do 
 begin 
  Label4.Caption := '正在下载 '+list_file.Items[i].Caption; 
  Application.ProcessMessages; 
  IdFTP1.ChangeDir(FInitPath); 
  path := list_file.Items[i].SubItems.Strings[0]; 
  if path <>'/' then 
  begin 
   IdFTP1.ChangeDir(path); 
   ForceDirectories(FExePath+path); 
   s1 := list_file.Items[i].Caption; 
   s2 := FExePath+path+'/'+list_file.Items[i].Caption; 
   IdFTP1.Get(s1,s2,True); 
  end 
  else 
  begin 
   s1 := list_file.Items[i].Caption; 
   s2 := FExePath+'/'+list_file.Items[i].Caption; 
   IdFTP1.Get(s1,s2,True); 
   //记录失败项 
   FIniFile.WriteString('error',list_file.Items[i].Caption,'成功'); 
  end; 
  except 
   //记录失败项 
   FIniFile.WriteString('error',list_file.Items[i].Caption,'失败'); 
  end; 
 end; 
 Label4.Caption := '所有文件更新完毕！'; 
 DeleteFile(FExePath+'update.ini'); 
 CopyFile(PChar(FExePath+'update_new.ini'),PChar(FExePath+'update.ini'),False); 
end; 
 
procedure TfrmMain.LoadIni; 
begin 
 ld_host.Text := FIniFile.ReadString('coninfo','host','******'); 
 ld_username.Text := FIniFile.ReadString('coninfo','user','******'); 
 ld_psw.Text := FIniFile.ReadString('coninfo','psw','******'); 
 ld_port.Text := FIniFile.ReadString('coninfo','port','21'); 
 cb_mode.ItemIndex := FIniFile.ReadInteger('coninfo','mode',1); 
 FMainExe := FIniFile.ReadString('coninfo','main','Main.exe'); 
 FParam := FIniFile.ReadString('coninfo','param',''); 
end; 
 
procedure TfrmMain.SaveIni; 
begin 
 FIniFile.WriteString('coninfo','host',ld_host.Text); 
 FIniFile.WriteString('coninfo','user',ld_username.Text); 
 FIniFile.WriteString('coninfo','psw',ld_psw.Text); 
 FIniFile.WriteString('coninfo','port',ld_port.Text); 
 FIniFile.WriteInteger('coninfo','mode',cb_mode.ItemIndex); 
end; 
 
end.