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249 lines
7.9 KiB
PHP
249 lines
7.9 KiB
PHP
<?php
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/**
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* PHP Readability
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*
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* Readability PHP 版本，详见
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* http://code.google.com/p/arc90labs-readability/
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*
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* ChangeLog:
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*
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* [+] 2011-02-17 初始化版本
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*
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* @author mingcheng<i.feelinglucky#gmail.com>
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* @date 2011-02-17
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* @link http://www.gracecode.com/
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*/
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define("READABILITY_VERSION", 0.12);
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class Readability2 {
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// 保存判定结果的标记位名称
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const ATTR_CONTENT_SCORE = "contentScore";
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// DOM 解析类目前只支持 UTF-8 编码
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const DOM_DEFAULT_CHARSET = "utf-8";
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// 当判定失败时显示的内容
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const MESSAGE_CAN_NOT_GET = "Sorry, readability was unable to parse this page for content. \n
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If you feel like it should have been able to,
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please let me know by mail: lucky[at]gracecode.com";
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// DOM 解析类（PHP5 已内置）
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protected $DOM = null;
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// 需要解析的源代码
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protected $source = "";
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// 章节的父元素列表
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private $parentNodes = array();
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// 需要删除的标签
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private $junkTags = Array("style", "form", "iframe", "script", "button", "input", "textarea");
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// 需要删除的属性
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private $junkAttrs = Array("style", "class", "onclick", "onmouseover", "align", "border", "margin");
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/**
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* 构造函数
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* @param $input_char 字符串的编码。默认 utf-8，可以省略
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*/
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function __construct($source, $input_char = "utf-8") {
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$this->source = $source;
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// DOM 解析类只能处理 UTF-8 格式的字符
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$source = mb_convert_encoding($source, 'HTML-ENTITIES', $input_char);
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// 预处理 HTML 标签，剔除冗余的标签等
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$source = $this->preparSource($source);
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// 生成 DOM 解析类
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$this->DOM = new DOMDocument('1.0', $input_char);
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try {
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//libxml_use_internal_errors(true);
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// 会有些错误信息，不过不要紧 :^)
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if (!@$this->DOM->loadHTML('<?xml encoding="'.Readability2::DOM_DEFAULT_CHARSET.'">'.$source)) {
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throw new Exception("Parse HTML Error!");
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}
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foreach ($this->DOM->childNodes as $item) {
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if ($item->nodeType == XML_PI_NODE) {
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$this->DOM->removeChild($item); // remove hack
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}
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}
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// insert proper
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$this->DOM->encoding = Readability2::DOM_DEFAULT_CHARSET;
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} catch (Exception $e) {
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// ...
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}
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}
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/**
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* 预处理 HTML 标签，使其能够准确被 DOM 解析类处理
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*
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* @return String
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*/
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private function preparSource($string) {
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// 剔除多余的 HTML 编码标记，避免解析出错
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preg_match("/charset=([\w|\-]+);?/", $string, $match);
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if (isset($match[1])) {
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$string = preg_replace("/charset=([\w|\-]+);?/", "", $string, 1);
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}
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// Replace all doubled-up <BR> tags with <P> tags, and remove fonts.
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$string = preg_replace("/<br\/?>[ \r\n\s]*<br\/?>/i", "</p><p>", $string);
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$string = preg_replace("/<\/?font[^>]*>/i", "", $string);
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return trim($string);
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}
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/**
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* 删除 DOM 元素中所有的 $TagName 标签
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*
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* @return DOMDocument
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*/
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private function removeJunkTag($RootNode, $TagName) {
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$Tags = $RootNode->getElementsByTagName($TagName);
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$i = 0;
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while($Tag = $Tags->item($i++)) {
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$parentNode = $Tag->parentNode;
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$parentNode->removeChild($Tag);
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}
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return $RootNode;
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}
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/**
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* 删除元素中所有不需要的属性
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*/
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private function removeJunkAttr($RootNode, $Attr) {
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$Tags = $RootNode->getElementsByTagName("*");
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$i = 0;
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while($Tag = $Tags->item($i++)) {
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$Tag->removeAttribute($Attr);
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}
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return $RootNode;
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}
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/**
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* 根据评分获取页面主要内容的盒模型
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* 判定算法来自：http://code.google.com/p/arc90labs-readability/
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*
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* @return DOMNode
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*/
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private function getTopBox() {
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// 获得页面所有的章节
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$allParagraphs = $this->DOM->getElementsByTagName("p");
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// Study all the paragraphs and find the chunk that has the best score.
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// A score is determined by things like: Number of <p>'s, commas, special classes, etc.
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$i = 0;
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while($paragraph = $allParagraphs->item($i++)) {
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$parentNode = $paragraph->parentNode;
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$contentScore = intval($parentNode->getAttribute(Readability2::ATTR_CONTENT_SCORE));
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$className = $parentNode->getAttribute("class");
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$id = $parentNode->getAttribute("id");
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// Look for a special classname
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if (preg_match("/(comment|meta|footer|footnote)/i", $className)) {
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$contentScore -= 50;
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} else if(preg_match(
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"/((^|\\s)(post|hentry|entry[-]?(content|text|body)?|article[-]?(content|text|body)?)(\\s|$))/i",
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$className)) {
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$contentScore += 25;
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}
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// Look for a special ID
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if (preg_match("/(comment|meta|footer|footnote)/i", $id)) {
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$contentScore -= 50;
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} else if (preg_match(
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"/^(post|hentry|entry[-]?(content|text|body)?|article[-]?(content|text|body)?)$/i",
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$id)) {
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$contentScore += 25;
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}
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// Add a point for the paragraph found
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// Add points for any commas within this paragraph
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if (strlen($paragraph->nodeValue) > 10) {
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$contentScore += strlen($paragraph->nodeValue);
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}
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// 保存父元素的判定得分
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$parentNode->setAttribute(Readability2::ATTR_CONTENT_SCORE, $contentScore);
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// 保存章节的父元素，以便下次快速获取
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array_push($this->parentNodes, $parentNode);
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}
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$topBox = $this->DOM->createElement('div', Readability2::MESSAGE_CAN_NOT_GET);
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// Assignment from index for performance.
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// See http://www.peachpit.com/articles/article.aspx?p=31567&seqNum=5
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for ($i = 0, $len = sizeof($this->parentNodes); $i < $len; $i++) {
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$parentNode = $this->parentNodes[$i];
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$contentScore = intval($parentNode->getAttribute(Readability2::ATTR_CONTENT_SCORE));
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$orgContentScore = intval($topBox->getAttribute(Readability2::ATTR_CONTENT_SCORE));
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if ($contentScore && $contentScore > $orgContentScore) {
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$topBox = $parentNode;
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}
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}
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// 此时，$topBox 应为已经判定后的页面内容主元素
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return $topBox;
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}
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/**
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* 获取 HTML 页面标题
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*
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* @return String
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*/
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public function getTitle() {
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$title = $this->DOM->getElementsByTagName("title");
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return $title->item(0);
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}
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/**
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* 获取页面的主要内容（Readability 以后的内容）
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*
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* @return Array
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*/
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public function getContent() {
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if (!$this->DOM) return false;
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// 获取页面标题
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$ContentTitle = $this->getTitle();
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// 获取页面主内容
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$ContentBox = $this->getTopBox();
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// 复制内容到新的 DOMDocument
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$Target = new DOMDocument;
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$Target->appendChild($Target->importNode($ContentBox, true));
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// 删除不需要的标签
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foreach ($this->junkTags as $tag) {
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$Target = $this->removeJunkTag($Target, $tag);
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}
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// 删除不需要的属性
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foreach ($this->junkAttrs as $attr) {
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$Target = $this->removeJunkAttr($Target, $attr);
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}
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// 多个数据，以数组的形式返回
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return Array(
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'title' => $ContentTitle ? $ContentTitle->nodeValue : "",
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'content' => $Target->saveHTML()
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);
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}
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function __destruct() { }
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}
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