PHP Cookbook读书笔记 – 第13章Web自动化

通过GET获得一个指定url的页面内容

有3种方式来获取一个URL的内容：

1. PHP提供的文件函数file_get_contents()
2. cURL扩展
3. PEAR中的HTTP_Request类

//方式1
$page = file_get_contents('http://www.example.com/robots.txt');

//方式2
$c = curl_init('http://www.example.com/robots.txt');
curl_setopt($c, CURLOPT_RETURNTRANSFER, true);
$page = curl_exec($c);
curl_close($c);

//方式3
require_once 'HTTP/Request.php';
$r = new HTTP_Request('http://www.example.com/robots.txt');
$r->sendRequest();
$page = $r->getResponseBody();

可以通过这些方式来获取XML文档，通过结合http_build_query()来建立一个查询字符串，可以通过url中加入username@password的形式来访问受保护的页面，通过cURL和PEAR的HTTP_Client类来跟踪重定向。

通过POST获得一个URL

让PHP模拟发送一个POST请求并获得服务器的反馈内容

//1
$url = 'http://www.example.com/submit.php';
$body = 'monkey=uncle&rhino=aunt';
$options = array('method' => 'POST', 'content' => $body);
$context = stream_context_create(array('http' => $options));
print file_get_contents($url, false, $context);

//2
$url = 'http://www.example.com/submit.php';
$body = 'monkey=uncle&rhino=aunt';
$c = curl_init($url);
curl_setopt($c, CURLOPT_POST, true);
curl_setopt($c, CURLOPT_POSTFIELDS, $body);
curl_setopt($c, CURLOPT_RETURNTRANSFER, true);
$page = curl_exec($c);
curl_close($c);

//3
require 'HTTP/Request.php';
$url = 'http://www.example.com/submit.php';
$r = new HTTP_Request($url);
$r->setMethod(HTTP_REQUEST_METHOD_POST);
$r->addPostData('monkey','uncle');
$r->addPostData('rhino','aunt');
$r->sendRequest();
$page = $r->getResponseBody();

通过Cookie获得一个URL

//2
$c = curl_init('http://www.example.com/needs-cookies.php');
curl_setopt($c, CURLOPT_COOKIE, 'user=ellen; activity=swimming');
curl_setopt($c, CURLOPT_RETURNTRANSFER, true);
$page = curl_exec($c);
curl_close($c);

//3
require 'HTTP/Request.php';
$r = new HTTP_Request('http://www.example.com/needs-cookies.php');
$r->addHeader('Cookie','user=ellen; activity=swimming');
$r->sendRequest();
$page = $r->getResponseBody();

通过Header获得一个URL

通过修改header中的信息可以来伪造 Referer 或 User-Agent 后请求目标URL，不少防盗链网站经常会采用判断Referer中的信息来源决定是否允许下载或访问资源。需要具备一些HTTP的HEADER背景知识。

标记网页

其实这个代码经过简单修改还可以应用到替换网页中的敏感关键字，这在天朝是很有用的一个功能

$body = '

I like pickles and herring.

A pickle picture

I have a herringbone-patterned toaster cozy.

Herring is not a real HTML element!
';

$words = array('pickle','herring');
$patterns = array();
$replacements = array();
foreach ($words as $i => $word) {
    $patterns[] = '/' . preg_quote($word) .'/i';
    $replacements[] = "\\0";
}

// Split up the page into chunks delimited by a
// reasonable approximation of what an HTML element
// looks like.
$parts = preg_split("{(<(?:\"[^\"]*\"|'[^']*'|[^'\">])*>)}",
                    $body,
                    -1,  // Unlimited number of chunks
                    PREG_SPLIT_DELIM_CAPTURE);
foreach ($parts as $i => $part) {
    // Skip if this part is an HTML element
    if (isset($part[0]) && ($part[0] == '<')) { continue; }
    // Wrap the words with s
    $parts[$i] = preg_replace($patterns, $replacements, $part);
}

// Reconstruct the body
$body = implode('',$parts);

print $body;

提取页面所有链接

也是一个很不错的功能，在做采集之类的程序时可以用的上

采用了tidy扩展的实现方式：

$doc = new DOMDocument();
$opts = array('output-xml' => true,
              // Prevent DOMDocument from being confused about entities
              'numeric-entities' => true);
$doc->loadXML(tidy_repair_file('linklist.html',$opts));
$xpath = new DOMXPath($doc);
// Tell $xpath about the XHTML namespace
$xpath->registerNamespace('xhtml','http://www.w3.org/1999/xhtml');
foreach ($xpath->query('//xhtml:a/@href') as $node) {
    $link = $node->nodeValue;
    print $link . "\n";

通过正则提取链接：

$html = file_get_contents('linklist.html');
$links = pc_link_extractor($html);
foreach ($links as $link) {
    print $link[0] . "\n";
}

function pc_link_extractor($html) {
    $links = array();
    preg_match_all('/]*)[\"\']?[^>]*>(.*?)<\/a>/i', $html,$matches,PREG_SET_ORDER); foreach($matches as $match) { $links[] = array($match[1],$match[2]); } return $links;

将文本转换为HTML

bbcode的概念和这个很像，所以将这个贴出来

function pc_text2html($s) {
  $s = htmlentities($s);
  $grafs = split("\n\n",$s);
  for ($i = 0, $j = count($grafs); $i < $j; $i++) {
    // 转换html超链接
    $grafs[$i] = preg_replace('/((ht|f)tp:\/\/[^\s&]+)/',
                              '$1',$grafs[$i]);    // 转换email链接
    $grafs[$i] = preg_replace('/[^@\s]+@([-a-z0-9]+\.)+[a-z]{2,}/i',        '$1',$grafs[$i]);    // 开始一个新段落
    $grafs[$i] = '

'.$grafs[$i].'

';  }  return implode("\n\n",$grafs);}

将HTML转换为文本

已经有现成的代码来实现这个功能http://www.chuggnutt.com/html2text.php

删除HTML和PHP标签

用这个函数strip_tags( ) 可以删除HTML和PHP标签