I would like to parse some content from an html file (no xml).
At the moment I retrieve the structure to parse using mochiweb_html:
1> inets:start().
2> {ok, {Status, Headers, Body}} = httpc:request("http://www.google.com").
3> {String, Attributes, Other} = mochiweb_html:parse(Body).
and the result is something like:
{<<"html">>,
[{<<"itemscope">>,<<"itemscope">>},
{<<"itemtype">>,<<"http://schema.org/WebPage">>}],
[{<<"head">>,[],
[{<<"meta">>,
[{<<"itemprop">>,<<"image">>},
{<<"content">>,<<"/images/google_favicon_128.png">>}],
[]},
{<<"title">>,[],[<<"Google">>]},
....
What is the best way to retrieve from a structure obtained from mochiweb_http all the elements in the web page that have a specific tag with a specific class (e.g., <span id="footer">)?
You could use mochiweb_xpath:
> mochiweb_xpath:execute("//span[@id='footer']",
mochiweb_html:parse(
"<html><body><span>not this one</span><span id='footer'>but this one</span></body></html>")).
[{<<"span">>,
[{<<"id">>,<<"footer">>}],
[<<"but this one">>]}]
It depends on your performance requirements.
The mochiweb result is in a 3-tuple form that could probably fairly easily be converted to input suitable for xmerl. Most of the work would be converting attribute names to atoms. Then you could use xmerl_xpath to do some pretty flexible querying.
Otherwise you could code something less flexible (but maybe faster) to walk the tree.
来源：https://stackoverflow.com/questions/16148202/parsing-the-result-obtained-from-mochiweb-html