如何通过 https 使用 IdHTTP 下载有进度的文件

Question

我正在尝试使用 indy10 http 组件 TIdHttp 下载文件，同时获得进度，我刚刚在应用程序文件夹中设置了库，同时使用 http URL 的代码它可以工作并取得进展，但是使用 https 它什么也不做它不会引发任何异常：/

 with TIdHTTP.Create(nil) do
   begin
    IOHndl:=TIdSSLIOHandlerSocketOpenSSL.Create(nil);
    Request.BasicAuthentication:=True;
    HandleRedirects:=True;
    IOHandler:=IOHndl;
    OnWork:=FOnWork;
    OnWorkBegin:=FOnWorkBegin;
    OnWorkEnd:=FOnWorkEnd;
    Get(FUrl,FStream);
end;

最好的问候

Answer 1

首先你必须创建一个小类来包装 HTTP 组件：

unit IdHTTPProgressU;

interface

uses
  Classes, IdBaseComponent, IdComponent, IdTCPConnection, IdTCPClient, IdHTTP, IdSSLOpenSSL;

{$M+}

type
  TIdHTTPProgress = class(TIdHTTP)
  private
    FProgress: Integer;
    FBytesToTransfer: Int64;
    FOnChange: TNotifyEvent;
    IOHndl: TIdSSLIOHandlerSocketOpenSSL;
    procedure HTTPWorkBegin(ASender: TObject; AWorkMode: TWorkMode; AWorkCountMax: Int64);
    procedure HTTPWork(ASender: TObject; AWorkMode: TWorkMode; AWorkCount: Int64);
    procedure HTTPWorkEnd(Sender: TObject; AWorkMode: TWorkMode);
    procedure SetProgress(const Value: Integer);
    procedure SetOnChange(const Value: TNotifyEvent);
  public
    Constructor Create(AOwner: TComponent);
    procedure DownloadFile(const aFileUrl: string; const aDestinationFile: String);
  published
    property Progress: Integer read FProgress write SetProgress;
    property BytesToTransfer: Int64 read FBytesToTransfer;
    property OnChange: TNotifyEvent read FOnChange write SetOnChange;
  end;

implementation

uses
  Sysutils;
{ TIdHTTPProgress }

constructor TIdHTTPProgress.Create(AOwner: TComponent);
begin
  inherited;
  IOHndl := TIdSSLIOHandlerSocketOpenSSL.Create(nil);
  Request.BasicAuthentication := True;
  HandleRedirects := True;
  IOHandler := IOHndl;
  ReadTimeout := 30000;
  OnWork := HTTPWork;
  OnWorkBegin := HTTPWorkBegin;
  OnWorkEnd := HTTPWorkEnd;
end;

procedure TIdHTTPProgress.DownloadFile(const aFileUrl: string; const aDestinationFile: String);
var
  LDestStream: TFileStream;
  aPath: String;
begin
  Progress := 0;
  FBytesToTransfer := 0;
  aPath := ExtractFilePath(aDestinationFile);
  if aPath <> '' then
    ForceDirectories(aPath);

  LDestStream := TFileStream.Create(aDestinationFile, fmCreate);
  try
    Get(aFileUrl, LDestStream);
  finally
    FreeAndNil(LDestStream);
  end;
end;

procedure TIdHTTPProgress.HTTPWork(ASender: TObject; AWorkMode: TWorkMode; AWorkCount: Int64);
begin
  if BytesToTransfer = 0 then // No Update File
    Exit;

  Progress := Round((AWorkCount / BytesToTransfer) * 100);
end;

procedure TIdHTTPProgress.HTTPWorkBegin(ASender: TObject; AWorkMode: TWorkMode; AWorkCountMax: Int64);
begin
  FBytesToTransfer := AWorkCountMax;
end;

procedure TIdHTTPProgress.HTTPWorkEnd(Sender: TObject; AWorkMode: TWorkMode);
begin
  FBytesToTransfer := 0;
  Progress := 100;
end;

procedure TIdHTTPProgress.SetOnChance(const Value: TNotifyEvent);
begin
  FOnChance := Value;
end;

procedure TIdHTTPProgress.SetProgress(const Value: Integer);
begin
  FProgress := Value;
  if Assigned(FOnChance) then
    FOnChance(Self);
end;

end.

我不会详细介绍 calss：只是说它实际上包装了一个 TIdhttp 组件并分配 3 个事件：OnBegin、onWork 和 OnEnd

方法DownloadFile 进行实际下载，

然后当你必须使用它时，你可以这样做：
在空窗体上放置一个 Button 和一个 PrograssBar。将IdHTTPProgressU 添加到使用列表中。

声明一个TIdHTTPProgress 和一个本地onChangeEvent 的变量

你的表单定义应该是这样的：

type
  TForm1 = class(TForm)
    Button1: TButton;
    ProgressBar1: TProgressBar;
    procedure FormCreate(Sender: TObject);
    procedure Button1Click(Sender: TObject);
  private
    procedure IdHTTPProgressOnChange(Sender : TObject);
  public
    IdHTTPProgress: TIdHTTPProgress;
  end;

然后你只需要实现方法：

    { TForm1 }

    procedure TForm1.Button1Click(Sender: TObject);
    begin
       IdHTTPProgress.OnChange := IdHTTPProgressOnChance;
          IdHTTPProgress.OnChance := IdHTTPProgressOnChance;
   IdHTTPProgress.DownloadFile('https://wordpress.org/latest.zip', 'latest.zip');
    end;

    procedure TForm1.FormCreate(Sender: TObject);
    begin
      IdHTTPProgress := TIdHTTPProgress.Create(Self);
    end;

    procedure TForm1.IdHTTPProgressOnChance(Sender: TObject);
    begin
      ProgressBar1.Position := TIdHTTPProgress(Sender).Progress;
      Application.ProcessMessages;
    end;

就是这样。试试看。