PHP implements page crawling and code analysis_PHP tutorial

When doing some weather forecast or RSS subscription programs, it is often necessary to capture non-local files. Generally, PHP is used to simulate browser access, and the URL address is accessed through HTTP requests, and then the HTML source code or XML data is obtained. We cannot directly output the data. We often need to extract the content and then format it to display it in a more friendly way.
1. The main method of crawling pages with PHP:
1. file() function
2. file_get_contents() function
3. fopen()->fread()->fclose() mode
4. curl method
5. fsockopen() function socket mode
6. Use plug-ins (such as: http://sourceforge.net/projects/snoopy/)
2. The main ways for PHP to parse html or xml code:
1. Regular expression 2. PHP DOMDocument object 3. Plug-in (such as:)
If you already know the above content very well, the following content can be passed by...
PHP crawl page
1. file() function

2. file_get_contents() function
Using file_get_contents and fopen must enable allow_url_fopen. Method: Edit php.ini and set allow_url_fopen = On. When allow_url_fopen is turned off, neither fopen nor file_get_contents can open remote files.

3. fopen()->fread()->fclose() mode

4. curl method
Using curl requires space to enable curl. Method: Modify php.ini under Windows, remove the semicolon in front of extension=php_curl.dll, and copy ssleay32.dll and libeay32.dll to C:WINDOWSsystem32; install the curl extension under Linux.

5. fsockopen() function socket mode
Whether the socket mode can be executed correctly is also related to the server settings. You can check which communication protocols are enabled by the server through phpinfo. For example, my local php socket does not enable http, so I can only use udp to test it.
n "; } else { fwrite($fp, "n"); echo fread($fp, 26); fclose($fp); } ?>
6. Plug-ins
There should be more plug-ins on the Internet. The snoopy plug-in was found online. If you are interested, you can research it.
PHP parses xml(html)
1. Regular expression:
(.*)',$lines_string,$ title); echo htmlspecialchars($title[0]); ?>
2. PHP DOMDocument() object
If there are syntax errors in the remote HTML or XML, PHP will report an error when parsing the DOM.
loadHTMLFile($url); $title=$html->getElementsByTagName('title '); echo $title->item(0)->nodeValue; ?>
3. Plug-in
This article takes PHP Simple HTML DOM Parser as an example to give a brief introduction. The syntax of simple_html_dom is similar to jQuery. It allows PHP to operate dom as easily as using jQuery to operate dom.
find('title'); echo $title[0]->plaintext; ?>
Of course, Chinese people are creative, and foreigners are often ahead in technology, but Chinese people are often better at using it, and often make some functions that foreigners dare not think of, such as remote crawling and analysis of PHP. Originally, It provides convenience for data integration. But Chinese people like this very much, so there are a large number of collection sites. They do not create any valuable content themselves, but rely on crawling other people's website content and making it their own. Enter the keyword "php small" in Baidu, and the first one on the suggestion list is "php thief program". Then I put the same keyword into Google, and I can only laugh and say nothing. For more questions, please go to the Q&A website (shenzhidao.com) to ask!

Excerpted from The Internet World Makes Something Out of Nothing

http://www.bkjia.com/PHPjc/478450.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/478450.htmlTechArticleWhen doing some weather forecast or RSS subscription programs, it is often necessary to capture non-local files. Generally, It uses php to simulate browser access and access the url address through http request...