Comment faire pour télécharger une image à partir d'une URL vers un répertoire local?

Api WinInet sont plus faciles que vous ne le pensez

Voici une complète console win32 programme. Peut être construit avec VS 2010 Express et descendre le chargement de windows SDK pour obtenir WinInit.

//imaged.cpp : Defines the entry point for the console application.
//
//Copy file from internet onto local file
//     Uses Wininet API
//   program takes 1 mandatory command line argument - URL string
//   it downloads ito the current directory, or whatever is passed
//   as the second parameter to DownloadURLImage.
//   optional parameter, the name of the file (excluding path), by default it uses the
//   filename from the URL string.
#include "stdafx.h"
#include <iostream>
#include <windows.h> 
#include <WinInet.h>  //from SDK
#include "string.h"
//#include<TCHAR.H>
//#include "Tchar.h"
using namespace std ;
int convertURLtofname (TCHAR * szURL, TCHAR * szname )
//extract the filename from the URL 
{
char aszfilename [100];
HRESULT result;
char achar[3], aszURL [100];
size_t nchars, i, j;
int fresult;
fresult = 0;
nchars= _tcslen(szURL);
i= nchars -1;
while ((i > 0) && (szURL[i] != '/') && (szURL[i] != '\\'))  {i--;}
j= 0; i++;
while (i < nchars) { szname [j++]= szURL[i++]; }
szname[j]=_T('\0');
// wcstombs ( aszfilename, szname, 100 );
//    cout << aszfilename << endl;
//----------------------------------------------
return fresult ;
}
int determinepathfilename (TCHAR * szURL, TCHAR * szpath, TCHAR * szname, TCHAR * szpathfilename)
{  
//use path and filename when supplied.  If filename (e.g. funkypic.jpg) is not supplied, then the
//filename will be extracted from the last part of the URL
int result ;
result= 0;
TCHAR szname_copy [100] ;
if ((szname == NULL) || (szname[0] == '\0'))
convertURLtofname (szURL, szname_copy);
else
_tcscpy (szname_copy, szname);
if ((szpath == NULL) || (szpath[0] == '\0'))
_tcscpy (szpathfilename, szname_copy);
else
{
_tcscpy (szpathfilename, szpath);
_tcscat (szpathfilename, szname_copy);
}
return result ;
}
bool GetFile (HINTERNET hOpen, //Handle from InternetOpen()
TCHAR *szURL,        //Full URL
TCHAR * szpath,
TCHAR * szname)   
{
DWORD dwSize;
TCHAR szHead[15];
BYTE * szTemp[1024];
HINTERNET  hConnect;
FILE * pFile;
TCHAR  szpathfilename [100] ;
szHead[0] = '\0';
if ( !(hConnect = InternetOpenUrl( hOpen, szURL, szHead, 15, INTERNET_FLAG_DONT_CACHE, 0)))
{
std::cout << "Error: InternetOpenUrl" << std::endl;
return 0;
}
determinepathfilename (szURL, szpath, szname, szpathfilename);
if  ( !(pFile = _tfopen (szpathfilename, _T("wb") ) ) )
{
std::cerr << "Error _tfopen" << std::endl;
return false;
}
do
{
//Keep copying in 1024 bytes chunks, while file has any data left.
//Note: bigger buffer will greatly improve performance.
if (!InternetReadFile (hConnect, szTemp, 1024,  &dwSize) )
{
fclose (pFile);
std::cerr << "Error InternetReadFile" << std::endl;
return FALSE;
}
if (!dwSize)
break;  //Condition of dwSize=0 indicate EOF. Stop.
else
fwrite(szTemp, sizeof (BYTE), dwSize , pFile);
}   //do
while (TRUE);
fflush (pFile);
fclose (pFile);
return TRUE;
}
int DownloadURLImage (TCHAR * szURL, TCHAR * szpath, TCHAR * szname)
{   int result ;
HINTERNET hInternet;
result= 0;
hInternet= InternetOpen (_T("imaged"),
INTERNET_OPEN_TYPE_DIRECT,  //__in  DWORD dwAccessType
NULL,                       //__in  LPCTSTR lpszProxyName,
NULL,                       //__in  LPCTSTR lpszProxyBypass,
NULL                        //_in   DWORD dwFlags
);
GetFile (hInternet, szURL, szpath, szname) ; 
InternetCloseHandle(hInternet);
return result ;
}
int _tmain(int argc, _TCHAR* argv[])
{
if (argc == 2)
{
DownloadURLImage (argv[1], NULL, NULL);
//DownloadURLImage (argv[1], _T"C:/", NULL);
}
else if (argc == 3)
{
DownloadURLImage (argv[1], NULL, argv[2]);
//DownloadURLImage (argv[1], _T"C:/", argv[2]);
}
else
{
cout << "Usage: imaged <image URL>" << endl ;
}
system("pause") ;
return 0;
}

OriginalL'auteur user672951

Utilisation Les Services Http Windows API.

OriginalL'auteur Sunny Milenov

Si le démarrage d'un nouveau processus est ok, vous pourriez avoir un coup d'oeil à WGET. (Et même si non, les sources sont disponibles, vous pouvez regarder là pour voir comment il a été mis en œuvre.)

OriginalL'auteur Reunanen