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This article mainly introduces how to use Perl to crawl web pages and submit forms, with a certain reference value, interested friends can refer to, I hope you can learn a lot after reading this article, the following let the editor take you to understand it.

Use Perl to crawl web pages and submit forms

Here is a brief introduction to the use of Perl to achieve grab web page source code, and the use of POST method to submit the form, and return the results. I can't tell you what's difficult, but let's talk about something simple.

The Perl modules mentioned here are:

UseLWP::Simple;useLWP::UserAgent; uses Perldoc to see the detailed usage.

1. Crawl web pages with Perl

If you just want to get a web page, it's easiest to use the functions in LWP::Simple. By calling the get ($url) function, you can get the contents of the relevant URL.

My$url=' http://freshair.npr.org/dayFA.cfm?todayDate=current' useLWP::Simple; my$content=get$url; die "Couldn'tget$url" unlessdefined$content

# $content is the content of the web page, here is some analysis of this content:

If ($content=~m/jazz/i) {print "They'retalkingaboutjazztodayonFreshAir!\ n";} else {print "FreshAirisapparentlyjazzlesstoday.\ n";}

It's very easy to understand. It is easy to get the content of a web page, but it is difficult to filter the content you need with rules.

2. Submit the form through POST

Some HTML tables use HTMLPOST to submit data to the server, here you can do this:

$response=$browser- > post ($url, [formkey1= > value1, formkey2= > value2,...],)

Example analysis: for example, submit a sequence in http://www.enzim.hu/hmmtop/html/submit.html) and return the result, which is realized by Perl. The code is as follows:

#! / usr/bin/Perl useLWP::UserAgent; my$browser=LWP::UserAgent- > new; $protein= "MSSSTPFDPYALSEHDEERPQNVQSKSRTAELQAEIDDTVGIMRDNINKVAERGERLTSI"; my$SUSUI_URL= "http://www.enzim.hu/hmmtop/server/hmmtop.cgi"; my$response=$browser- > post ($SUSUI_URL, ['if'= > $protein,]); if ($response- > is_success) {print$response- > content;} else {print" Badluckthistime\ n ";}

By analyzing the page of http://www.enzim.hu/hmmtop/html/submit.html, we can see that there is only one input to be submitted, that is, name= "if". $protein is the sequence to be submitted. $response- > content is the result returned.

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