vb.net - .Net - WebClient or HttpWebRequest to get content -


i developed application download multiple images website pattern, using webclient. when started this, idea fast , easy app, made form with:

  • webbrowser (wb)
  • multiline textbox put multiple urls crawl
  • listbox storage link of each photo
  • textbox select targetpath
  • button start process

it easy, needed find labels of each photos using + htmlelement + wb.document.all. once got links, used webclient download them fast (client.downloadfile(path, filename)). works flawlessly.

now app bigger, has more websites crawl , use backgroundworker manage this. started learn how bgworker works, , noticed cannot use control webbrowser, gives exception, cannot use wb.document.all links.

i found amazing example in codeproject of how download file bgworker, 1 concretely:

http://www.codeproject.com/articles/17979/downloading-files-in-net-with-all-information-prog

he uses httpwebrequest, seems harder implement if first need links.

my question is: should recode app use httpwebrequest or can adapt current code (webbrowser implicated) use bgworker? if it's possible use webbrowser bgworker, 1 correct way make it?

my current relevant code (i call function when click button). put necessary lines only:

function extractlicenseplate()         dim client new webclient         dim totalphotos integer = 0         dim finalplate string = "[no licenseplate found]"         dim totalcarslist integer = txturls.lines.where(function(l) not string.isnullorwhitespace(l)).count()      = 0 totalcarslist - 1         wb.navigate(txturls.lines(i))         waitforpageload()          each ele htmlelement in wb.document.all             'ald             if comboproviders.selectedindex = 0                 if ele.getattribute("src").tolower.contains("iddoc")                     dim imgsrc string = ele.getattribute("src")                     lstphotos.items.add(imgsrc)                 end if                 'get license plate make folders                 if ele.getattribute("action").tolower.contains("matr=")                     dim fullurlname string = ele.getattribute("action")                     finalplate = fullurlname.split("=")(3).substring(0, 7)                 end if             end if         next          if (not directory.exists(txtdirectory.text & "\" & finalplate))             if not (finalplate = "[no licenseplate found]")                 directory.createdirectory(txtdirectory.text & "\" & finalplate)             end if         end if          j = 0 lstphotos.items.count - 1             client.downloadfile(lstphotos.items(j).tostring, txtdirectory.text & "\" & finalplate & "\" & finalplate & j & ".jpg")             client.dispose()         next j         lstphotos.items.clear()     next     return 0 end function

any appreciate.

thanks everyone.

i wouldn't use background worker, i'd write threads myself. here's example:

dim wc new webclient  dim trdmain new thread(addressof fdownload)  protected sub srun()     trdmain.isbackground = true     trdmain.start() end sub  protected function fdownload()       ' iterate through , download     each str string in strimages         wc.downloadstring(str, "your location")     next      return true ' terminate thread end function

this implies have array of urls of images wish download. implement code, simple , effective.


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