Web::Scraper 页面提取分析
一组用来提取HTML文档中元素内容的工具集,它能够理解HTML和CSS选择器以及XPath表达式。
语法
use URI; use Web::Scraper; # First, create your scraper block my $tweets = scraper { # Parse all LIs with the class "status", store them into a resulting # array 'tweets'. We embed another scraper for each tweet. process "li.status", "tweets[]" => scraper { # And, in that array, pull in the elementy with the class # "entry-content", "entry-date" and the link process ".entry-content", body => 'TEXT'; process ".entry-date", when => 'TEXT'; process 'a[rel="bookmark"]', link => '@href'; }; }; my $res = $tweets->scrape( URI->new("http://twitter.com/miyagawa") ); # The result has the populated tweets array for my $tweet (@{$res->{tweets}}) { print "$tweet->{body} $tweet->{when} (link: $tweet->{link})\n"; }
process
scraper { process "tag.class", key => 'TEXT'; process '//tag[contains(@foo, "bar")]', key2 => '@attr'; process '//comment()', 'comments[]' => 'TEXT'; };
如果你传入的参数是URI或HTTP response,那Web::Scaper自动去寻找Content-Type header和META标签以判断文件编码。否则你压根先把HTML内容解码为Unicode后再传给scape函数。
$res = $scraper->scrape(URI->new($uri)); $res = $scraper->scrape($html_content); $res = $scraper->scrape(\$html_content); $res = $scraper->scrape($http_response); $res = $scraper->scrape($html_element);
当你把HTML内容作为参数传给scrape函数时,你还要考虑一个问题:HTML文档中出现 相对路径怎么办?所以这个时候你可以把base url一并作为参数传进去。
res= scraper->scrape($html_content, "http://example.com/foo");
它有两个参数,当第一个参数以"//"或"id("开头时作为XPath对待;否则作为HTML或CSS选择器对待。
# <span class="date">2008/12/21</span> # date => "2008/12/21" process ".date", date => 'TEXT'; # <div class="body"><a href="http://example.com/">foo</a></div> # link => URI->new("http://example.com/") process ".body > a", link => '@href'; # <div class="body"><!-- HTML Comment here --><a href="http://example.com/">foo</a></div> # comment => " HTML Comment here " # # NOTES: A comment nodes are accessed when installed # the HTML::TreeBuilder::XPath (version >= 0.14) and/or # the HTML::TreeBuilder::LibXML (version >= 0.13) process "//div[contains(@class, 'body')]/comment()", comment => 'TEXT'; # <div class="body"><a href="http://example.com/">foo</a></div> # link => URI->new("http://example.com/"), text => "foo" process ".body > a", link => '@href', text => 'TEXT'; # <ul><li>foo</li><li>bar</li></ul> # list => [ "foo", "bar" ] process "li", "list[]" => "TEXT"; # <ul><li id="1">foo</li><li id="2">bar</li></ul> # list => [ { id => "1", text => "foo" }, { id => "2", text => "bar" } ]; process "li", "list[]" => { id => '@id', text => "TEXT" };