Пример HTTP Get – загружаем файлы и страницы из Интернета

{*************************************************************}
{            HTTPGet component for Delphi 32                  }
{ Version:   1.94                                             }
{ E-Mail:    info@utilmind.com                                }
{ WWW:       http://www.utilmind.com                          }
{ Created:   October  19, 1999                                }
{ Modified:  June 6, 2000                                     }
{ Legal:     Copyright (c) 1999-2000, UtilMind Solutions      }
{*************************************************************}
{ PROPERTIES:                                                 }
{   Agent: String - User Agent                                }
{                                                             }
{*  BinaryData: Boolean - This setting specifies which type   }
{*                        of data will taken from the web.    }
{*                        If you set this property TRUE then  }
{*                        component will determinee the size  }
{*                        of files *before* getting them from }
{*                        the web.                            }
{*                        If this property is FALSE then as we}
{*                        do not knows the file size the      }
{*                        OnProgress event will doesn't work. }
{*                        Also please remember that is you set}
{*                        this property as TRUE you will not  }
{*                        capable to get from the web ASCII   }
{*                        data and ofter got OnError event.   }
{                                                             }
{   FileName: String - Path to local file to store the data   }
{                      taken from the web                     }
{   Password, UserName - set this properties if you trying to }
{                        get data from password protected     }
{                        directories.                         }
{   Referer: String - Additional data about referer document  }
{   URL: String - The url to file or document                 }
{   UseCache: Boolean - Get file from the Internet Explorer's }
{                       cache if requested file is cached.    }
{*************************************************************}
{ METHODS:                                                    }
{   GetFile - Get the file from the web specified in the URL  }
{             property and store it to the file specified in  }
{             the FileName property                           }
{   GetString - Get the data from web and return it as usual  }
{               String. You can receive this string hooking   }
{               the OnDoneString event.                       }
{   Abort - Stop the current session                          }
{*************************************************************}
{ EVENTS:                                                     }
{   OnDoneFile - Occurs when the file is downloaded           }
{   OnDoneString - Occurs when the string is received         }
{   OnError - Occurs when error happend                       }
{   OnProgress - Occurs at the receiving of the BINARY DATA   }
{*************************************************************}
{ Please see demo program for more information.               }
{*************************************************************}
{                     IMPORTANT NOTE:                         }
{ This software is provided 'as-is', without any express or   }
{ implied warranty. In no event will the author be held       }
{ liable for any damages arising from the use of this         }
{ software.                                                   }
{ Permission is granted to anyone to use this software for    }
{ any purpose, including commercial applications, and to      }
{ alter it and redistribute it freely, subject to the         }
{ following restrictions:                                     }
{ 1. The origin of this software must not be misrepresented,  }
{    you must not claim that you wrote the original software. }
{    If you use this software in a product, an acknowledgment }
{    in the product documentation would be appreciated but is }
{    not required.                                            }
{ 2. Altered source versions must be plainly marked as such,  }
{    and must not be misrepresented as being the original     }
{    software.                                                }
{ 3. This notice may not be removed or altered from any       }
{    source distribution.                                     }
{*************************************************************}
 
unit HTTPGet;
 
interface
 
uses
  Windows, Messages, SysUtils, Classes, WinInet;
 
type
  TOnProgressEvent = procedure(Sender: TObject; TotalSize, Readed: Integer) of object;
  TOnDoneFileEvent = procedure(Sender: TObject; FileName: String; FileSize: Integer) of object;
  TOnDoneStringEvent = procedure(Sender: TObject; Result: String) of object;
 
  THTTPGetThread = class(TThread)
  private
    FTAcceptTypes,
    FTAgent,
    FTURL,
    FTFileName,
    FTStringResult,
    FTUserName,
    FTPassword,
    FTPostQuery,
    FTReferer: String;
    FTBinaryData,
    FTUseCache: Boolean;
 
    FTResult: Boolean;
    FTFileSize: Integer;
    FTToFile: Boolean;
 
    BytesToRead, BytesReaded: DWord;
 
    FTProgress: TOnProgressEvent;
 
    procedure UpdateProgress;
  protected
    procedure Execute; override;
  public
    constructor Create(aAcceptTypes, aAgent, aURL, aFileName, aUserName, aPassword, 
      aPostQuery, aReferer: String; aBinaryData, aUseCache: 
      Boolean; aProgress: TOnProgressEvent; aToFile: Boolean);
  end;
 
  THTTPGet = class(TComponent)
  private
    FAcceptTypes: String;
    FAgent: String;
    FBinaryData: Boolean;
    FURL: String;
    FUseCache: Boolean;
    FFileName: String;
    FUserName: String;
    FPassword: String;
    FPostQuery: String;
    FReferer: String;
    FWaitThread: Boolean;
 
    FThread: THTTPGetThread;
    FError: TNotifyEvent;
    FResult: Boolean;
 
    FProgress: TOnProgressEvent;
    FDoneFile: TOnDoneFileEvent;
    FDoneString: TOnDoneStringEvent;
 
    procedure ThreadDone(Sender: TObject);
  public
    constructor Create(aOwner: TComponent); override;
    destructor Destroy; override;
 
    procedure GetFile;
    procedure GetString;
    procedure Abort;
  published
    property AcceptTypes: String read FAcceptTypes write FAcceptTypes;
    property Agent: String read FAgent write FAgent;
    property BinaryData: Boolean read FBinaryData write FBinaryData;
    property URL: String read FURL write FURL;
    property UseCache: Boolean read FUseCache write FUseCache;
    property FileName: String read FFileName write FFileName;
    property UserName: String read FUserName write FUserName;
    property Password: String read FPassword write FPassword;
    property PostQuery: String read FPostQuery write FPostQuery;
    property Referer: String read FReferer write FReferer;
    property WaitThread: Boolean read FWaitThread write FWaitThread;
 
    property OnProgress: TOnProgressEvent read FProgress write FProgress;
    property OnDoneFile: TOnDoneFileEvent read FDoneFile write FDoneFile;
    property OnDoneString: TOnDoneStringEvent read FDoneString write FDoneString;
    property OnError: TNotifyEvent read FError write FError;
  end;
 
procedure Register;
 
implementation
 
//  THTTPGetThread
 
constructor THTTPGetThread.Create(aAcceptTypes, aAgent, aURL, aFileName, aUserName, 
  aPassword, aPostQuery, aReferer: String; aBinaryData, aUseCache: 
  Boolean; aProgress: TOnProgressEvent; aToFile: Boolean);
begin
  FreeOnTerminate := True;
  inherited Create(True);
 
  FTAcceptTypes := aAcceptTypes;
  FTAgent := aAgent;
  FTURL := aURL;
  FTFileName := aFileName;
  FTUserName := aUserName;
  FTPassword := aPassword;
  FTPostQuery := aPostQuery;
  FTReferer := aReferer;
  FTProgress := aProgress;
  FTBinaryData := aBinaryData;
  FTUseCache := aUseCache;
 
  FTToFile := aToFile;
  Resume;
end;
 
procedure THTTPGetThread.UpdateProgress;
begin
  FTProgress(Self, FTFileSize, BytesReaded);
end;
 
procedure THTTPGetThread.Execute;
var
  hSession, hConnect, hRequest: hInternet;
  HostName, FileName: String;
  f: File;
  Buf: Pointer;
  dwBufLen, dwIndex: DWord;
  Data: Array[0..$400] of Char;
  TempStr: String;
  RequestMethod: PChar;
  InternetFlag: DWord;
  AcceptType: LPStr;
 
  procedure ParseURL(URL: String; var HostName, FileName: String);
 
    procedure ReplaceChar(c1, c2: Char; var St: String);
    var
      p: Integer;
    begin
      while True do
       begin
        p := Pos(c1, St);
        if p = 0 then Break
        else St[p] := c2;
       end;
    end;
 
  var
    i: Integer;
  begin
    if Pos('http://', LowerCase(URL)) <> 0 then
      System.Delete(URL, 1, 7);
 
    i := Pos('/', URL);
    HostName := Copy(URL, 1, i);
    FileName := Copy(URL, i, Length(URL) - i + 1);
 
    if (Length(HostName) > 0) and (HostName[Length(HostName)] = '/') then
      SetLength(HostName, Length(HostName) - 1);
  end;
 
 procedure CloseHandles;
 begin
   InternetCloseHandle(hRequest);
   InternetCloseHandle(hConnect);
   InternetCloseHandle(hSession);
 end;
 
begin
  try
    ParseURL(FTURL, HostName, FileName);
 
    if Terminated then
     begin
      FTResult := False;
      Exit;
     end;
 
    if FTAgent <> '' then
     hSession := InternetOpen(PChar(FTAgent),
       INTERNET_OPEN_TYPE_PRECONFIG, nil, nil, 0)
    else
     hSession := InternetOpen(nil,
       INTERNET_OPEN_TYPE_PRECONFIG, nil, nil, 0);
 
    hConnect := InternetConnect(hSession, PChar(HostName),
      INTERNET_DEFAULT_HTTP_PORT, PChar(FTUserName), PChar(FTPassword), INTERNET_SERVICE_HTTP, 0, 0);
 
    if FTPostQuery = '' then RequestMethod := 'GET'
    else RequestMethod := 'POST';
 
    if FTUseCache then InternetFlag := 0
    else InternetFlag := INTERNET_FLAG_RELOAD;
 
    AcceptType := PChar('Accept: ' + FTAcceptTypes);
    hRequest := HttpOpenRequest(hConnect, RequestMethod, PChar(FileName), 'HTTP/1.0',
                PChar(FTReferer), @AcceptType, InternetFlag, 0);
 
    if FTPostQuery = '' then
     HttpSendRequest(hRequest, nil, 0, nil, 0)
    else
     HttpSendRequest(hRequest, 'Content-Type: application/x-www-form-urlencoded', 47,
                     PChar(FTPostQuery), Length(FTPostQuery));
 
    if Terminated then
     begin
      CloseHandles;
      FTResult := False;
      Exit;
     end;
 
    dwIndex  := 0;
    dwBufLen := 1024;
    GetMem(Buf, dwBufLen);
 
    FTResult := HttpQueryInfo(hRequest, HTTP_QUERY_CONTENT_LENGTH,
                              Buf, dwBufLen, dwIndex);
 
    if Terminated then
     begin
      FreeMem(Buf);
      CloseHandles;
      FTResult := False;
      Exit;
     end;
 
    if FTResult or not FTBinaryData then
     begin
      if FTResult then
        FTFileSize := StrToInt(StrPas(Buf));
 
      BytesReaded := 0;
 
      if FTToFile then
       begin
        AssignFile(f, FTFileName);
        Rewrite(f, 1);
       end
      else FTStringResult := '';
 
      while True do
       begin
        if Terminated then
         begin
          if FTToFile then CloseFile(f);
          FreeMem(Buf);
          CloseHandles;
 
          FTResult := False;
          Exit;
         end;
 
        if not InternetReadFile(hRequest, @Data, SizeOf(Data), BytesToRead) then Break
        else
         if BytesToRead = 0 then Break
         else
          begin
           if FTToFile then
            BlockWrite(f, Data, BytesToRead)
           else
            begin
             TempStr := Data;
             SetLength(TempStr, BytesToRead);
             FTStringResult := FTStringResult + TempStr;
            end;
 
           inc(BytesReaded, BytesToRead);
           if Assigned(FTProgress) then
            Synchronize(UpdateProgress);
          end;
       end;
 
      if FTToFile then
        FTResult := FTFileSize = Integer(BytesReaded)
      else
       begin
        SetLength(FTStringResult, BytesReaded);
        FTResult := BytesReaded <> 0;
       end;
 
      if FTToFile then CloseFile(f);
     end;
 
    FreeMem(Buf);
 
    CloseHandles;
  except
  end;
end;
 
// HTTPGet
 
constructor THTTPGet.Create(aOwner: TComponent);
begin
  inherited Create(aOwner);
  FAcceptTypes := '*/*';
  FAgent := 'UtilMind HTTPGet';
end;
 
destructor THTTPGet.Destroy;
begin
  Abort;
  inherited Destroy;
end;
 
procedure THTTPGet.GetFile;
var
  Msg: TMsg;
begin
  if not Assigned(FThread) then
   begin
    FThread := THTTPGetThread.Create(FAcceptTypes, FAgent, FURL, FFileName, FUserName, 
      FPassword, FPostQuery, FReferer, FBinaryData, FUseCache, FProgress, True);
    FThread.OnTerminate := ThreadDone;
    if FWaitThread then
    while Assigned(FThread) do
     while PeekMessage(Msg, 0, 0, 0, PM_REMOVE) do
      begin
        TranslateMessage(Msg);
        DispatchMessage(Msg);
      end;
   end
end;
 
procedure THTTPGet.GetString;
var
  Msg: TMsg;
begin
  if not Assigned(FThread) then
   begin
    FThread := THTTPGetThread.Create(FAcceptTypes, FAgent, FURL, FFileName, FUserName, 
      FPassword, FPostQuery, FReferer, FBinaryData, FUseCache, FProgress, False);
    FThread.OnTerminate := ThreadDone;
    if FWaitThread then
     while PeekMessage(Msg, 0, 0, 0, PM_REMOVE) do
      begin
        TranslateMessage(Msg);
        DispatchMessage(Msg);
      end;
   end
end;
 
procedure THTTPGet.Abort;
begin
  if Assigned(FThread) then
   begin
    FThread.Terminate;
    FThread.FTResult := False;
   end;
end;
 
procedure THTTPGet.ThreadDone(Sender: TObject);
begin
  FResult := FThread.FTResult;
  if FResult then
   if FThread.FTToFile then
    if Assigned(FDoneFile) then FDoneFile(Self, FThread.FTFileName, FThread.FTFileSize) else
   else
    if Assigned(FDoneString) then FDoneString(Self, FThread.FTStringResult) else
  else
   if Assigned(FError) then FError(Self);
  FThread := nil;
end;
 
procedure Register;
begin
  RegisterComponents('UtilMind', [THTTPGet]);
end;
 
end.

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