php中RSS订阅类的使用方法

这篇文章主要介绍了php生成RSS订阅的方法,较为详细的分析了一个RSS订阅类及其具体使用技巧,非常具有实用价值,需要的朋友可以参考下

本文实例讲述了php生成RSS订阅的方法。具体分析如下：

RSS（简易信息聚合，也叫聚合内容）是一种描述和同步网站内容的格式。RSS可以是以下三个解释的其中一个： Really Simple Syndication；RDF (Resource Description Framework) Site Summary； Rich Site Summary。但其实这三个解释都是指同一种Syndication的技术。RSS目前广泛用于网上新闻频道，blog和wiki。使用RSS订阅能更快地获取信息，网站提供RSS输出，有利于让用户获取网站内容的最新更新。网络用户可以在客户端借助于支持RSS的聚合工具软件，在不打开网站内容页面的情况下阅读支持RSS输出的网站内容。
从技术上来说一个RSS文件就是一段规范的XML数据，该文件一般以rss，xml或者rdf作为后缀，下面是一段 rss 文件的内容示例：

代码如下:

<?xml version="1.0" encoding="utf-8"?> 
<rss version="2.0"> 
<channel> 
<title>PHP中文网</title> 
<link>//www.php.cn/</link> 
<description>PHP中文网</description> 
<item> 
<title>RSS Tutorial</title> 
<link>网站地址/rss</link> 
<description>New RSS tutorial on W3School</description> 
</item> 
<item> 
<title>XML Tutorial</title> 
<link>网站地址/xml</link> 
<description>New XML tutorial on W3School</description> 
</item> 
</channel> 
</rss>

下面分享一段使用 php 动态生成 RSS 的代码示例：

代码如下:

<?php 
/** 
** php 动态生成 RSS 类 
**/ 
define("TIME_ZONE",""); 
define("FEEDCREATOR_VERSION","www.jb51.net");//您的网址 
class FeedItem extends HtmlDescribable{ 
    var $title,$description,$link; 
    var $author,$authorEmail,$image,$category,$comments,$guid,$source,$creator;
    var $date;
    var $additionalElements=Array(); 
} 
 
class FeedImage extends HtmlDescribable{ 
    var $title,$url,$link; 
    var $width,$height,$description; 
} 
 
class HtmlDescribable{ 
    var $descriptionHtmlSyndicated; 
    var $descriptionTruncSize; 
 
    function getDescription(){ 
        $descriptionField=new FeedHtmlField($this->description); 
        $descriptionField->syndicateHtml=$this->descriptionHtmlSyndicated;
        $descriptionField->truncSize=$this->descriptionTruncSize;
        return $descriptionField->output(); 
    } 
} 
 
class FeedHtmlField{ 
    var $rawFieldContent; 
    var $truncSize,$syndicateHtml; 
    function FeedHtmlField($parFieldContent){ 
        if($parFieldContent){ 
            $this->rawFieldContent=$parFieldContent; 
        } 
    } 
    function output(){ 
        if(!$this->rawFieldContent){ 
            $result=""; 
        }    elseif($this->syndicateHtml){ 
            $result="<![CDATA[".$this->rawFieldContent."]]>"; 
        }else{ 
            if($this->truncSize and is_int($this->truncSize)){ 
                $result=FeedCreator::iTrunc(htmlspecialchars($this->rawFieldContent),$this->truncSize);
            }else{ 
                $result=htmlspecialchars($this->rawFieldContent); 
            } 
        } 
        return $result; 
    } 
} 
 
class UniversalFeedCreator extends FeedCreator{ 
    var $_feed; 
    function _setFormat($format){ 
        switch (strtoupper($format)){ 
            case "2.0": 
                // fall through 
            case "RSS2.0": 
                $this->_feed=new RSSCreator20(); 
                break; 
            case "0.91": 
                // fall through 
            case "RSS0.91": 
                $this->_feed=new RSSCreator091(); 
                break; 
            default: 
                $this->_feed=new RSSCreator091(); 
                break; 
        } 
        $vars=get_object_vars($this); 
        foreach ($vars as $key => $value){ 
            // prevent overwriting of properties "contentType","encoding"; do not copy "_feed" itself 
            if(!in_array($key, array("_feed","contentType","encoding"))){ 
                $this->_feed->{$key}=$this->{$key}; 
            } 
        } 
    } 
 
    function createFeed($format="RSS0.91"){ 
        $this->_setFormat($format); 
        return $this->_feed->createFeed(); 
    } 
 
    function saveFeed($format="RSS0.91",$filename="",$displayContents=true){ 
        $this->_setFormat($format); 
        $this->_feed->saveFeed($filename,$displayContents); 
    } 
 
    function useCached($format="RSS0.91",$filename="",$timeout=3600){ 
        $this->_setFormat($format); 
        $this->_feed->useCached($filename,$timeout); 
    } 
} 
 
class FeedCreator extends HtmlDescribable{ 
    var $title,$description,$link; 
    var $syndicationURL,$image,$language,$copyright,$pubDate,$lastBuildDate,$editor,$editorEmail,$webmaster,$category,$docs,$ttl,$rating,$skipHours,$skipDays;
    var $xslStyleSheet=""; 
    var $items=Array(); 
    var $contentType="application/xml"; 
    var $encoding="utf-8"; 
    var $additionalElements=Array(); 
 
    function addItem($item){ 
        $this->items[]=$item; 
    } 
 
    function clearItem2Null(){ 
        $this->items=array(); 
    } 
 
    function iTrunc($string,$length){ 
        if(strlen($string)<=$length){ 
            return $string; 
        } 
 
        $pos=strrpos($string,"."); 
        if($pos>=$length-4){ 
            $string=substr($string,0,$length-4); 
            $pos=strrpos($string,"."); 
        } 
        if($pos>=$length*0.4){ 
            return substr($string,0,$pos+1)." ..."; 
        } 
 
        $pos=strrpos($string," "); 
        if($pos>=$length-4){ 
            $string=substr($string,0,$length-4); 
            $pos=strrpos($string," "); 
        } 
        if($pos>=$length*0.4){ 
            return substr($string,0,$pos)." ..."; 
        } 
 
        return substr($string,0,$length-4)." ..."; 
    } 
 
    function _createGeneratorComment(){ 
        return "<!-- generator=\"".FEEDCREATOR_VERSION."\" -->\n"; 
    } 
 
    function _createAdditionalElements($elements,$indentString=""){ 
        $ae=""; 
        if(is_array($elements)){ 
            foreach($elements AS $key => $value){ 
                $ae.= $indentString."<$key>$value</$key>\n"; 
            } 
        } 
        return $ae; 
    } 
 
    function _createStylesheetReferences(){ 
        $xml=""; 
        if($this->cssStyleSheet) $xml .= "<?xml-stylesheet href=\"".$this->cssStyleSheet."\" type=\"text/css\"?>\n"; 
        if($this->xslStyleSheet) $xml .= "<?xml-stylesheet href=\"".$this->xslStyleSheet."\" type=\"text/xsl\"?>\n"; 
        return $xml; 
    } 
 
    function createFeed(){} 
 
    function _generateFilename(){ 
        $fileInfo=pathinfo($_SERVER["PHP_SELF"]); 
        return substr($fileInfo["basename"],0,-(strlen($fileInfo["extension"])+1)).".xml"; 
    } 
 
    function _redirect($filename){ 
        Header("Content-Type: ".$this->contentType."; charset=".$this->encoding."; filename=".basename($filename)); 
        Header("Content-Disposition: inline; filename=".basename($filename)); 
        readfile($filename,"r"); 
        die(); 
    } 
 
    function useCached($filename="",$timeout=3600){ 
        $this->_timeout=$timeout; 
        if($filename==""){ 
            $filename=$this->_generateFilename(); 
        } 
        if(file_exists($filename) && (time()-filemtime($filename) < $timeout)){ 
            $this->_redirect($filename); 
        } 
    } 
 
    function saveFeed($filename="",$displayContents=true){ 
        if($filename==""){ 
            $filename=$this->_generateFilename(); 
        } 
        $feedFile=fopen($filename,"w+"); 
        if($feedFile){ 
            fputs($feedFile,$this->createFeed()); 
            fclose($feedFile); 
            if($displayContents){ 
                $this->_redirect($filename); 
            } 
        }else{ 
            echo "<br /><b>Error creating feed file, please check write permissions.</b><br />"; 
        } 
    } 
} 
 
class FeedDate{ 
    var $unix; 
    function FeedDate($dateString=""){ 
        if($dateString=="") $dateString=date("r"); 
        if(is_integer($dateString)){ 
            $this->unix=$dateString; 
            return; 
        } 
        if(preg_match("~(?:(?:Mon|Tue|Wed|Thu|Fri|Sat|Sun),\\s+)?(\\d{1,2})\\s+([a-zA-Z]{3})\\s+(\\d{4})\\s+(\\d{2}):(\\d{2}):(\\d{2})\\s+(.*)~",$dateString,$matches)){ 
            $months=Array("Jan"=>1,"Feb"=>2,"Mar"=>3,"Apr"=>4,"May"=>5,"Jun"=>6,"Jul"=>7,"Aug"=>8,"Sep"=>9,"Oct"=>10,"Nov"=>11,"Dec"=>12); 
            $this->unix=mktime($matches[4],$matches[5],$matches[6],$months[$matches[2]],$matches[1],$matches[3]); 
            if(substr($matches[7],0,1)==&#39;+&#39; OR substr($matches[7],0,1)==&#39;-&#39;){ 
                $tzOffset=(substr($matches[7],0,3) * 60 + substr($matches[7],-2)) * 60; 
            }else{ 
                if(strlen($matches[7])==1){ 
                    $oneHour=3600; 
                    $ord=ord($matches[7]); 
                    if($ord < ord("M")){ 
                        $tzOffset=(ord("A") - $ord - 1) * $oneHour; 
                    } elseif($ord >= ord("M") && $matches[7]!="Z"){ 
                        $tzOffset=($ord - ord("M")) * $oneHour; 
                    } elseif($matches[7]=="Z"){ 
                        $tzOffset=0; 
                    } 
                } 
                switch ($matches[7]){ 
                    case "UT": 
                    case "GMT":    $tzOffset=0; 
                } 
            } 
            $this->unix += $tzOffset; 
            return; 
        } 
        if(preg_match("~(\\d{4})-(\\d{2})-(\\d{2})T(\\d{2}):(\\d{2}):(\\d{2})(.*)~",$dateString,$matches)){ 
            $this->unix=mktime($matches[4],$matches[5],$matches[6],$matches[2],$matches[3],$matches[1]); 
            if(substr($matches[7],0,1)==&#39;+&#39; OR substr($matches[7],0,1)==&#39;-&#39;){ 
                $tzOffset=(substr($matches[7],0,3) * 60 + substr($matches[7],-2)) * 60; 
            }else{ 
                if($matches[7]=="Z"){ 
                    $tzOffset=0; 
                } 
            } 
            $this->unix += $tzOffset; 
            return; 
        } 
        $this->unix=0; 
    } 
 
    function rfc822(){ 
        $date=gmdate("Y-m-d H:i:s",$this->unix); 
        if(TIME_ZONE!="") $date .= " ".str_replace(":","",TIME_ZONE); 
        return $date; 
    } 
 
    function iso8601(){ 
        $date=gmdate("Y-m-d H:i:s",$this->unix); 
        $date=substr($date,0,22) . &#39;:&#39; . substr($date,-2); 
        if(TIME_ZONE!="") $date=str_replace("+00:00",TIME_ZONE,$date); 
        return $date; 
    } 
 
    function unix(){ 
        return $this->unix; 
    } 
} 
 
class RSSCreator10 extends FeedCreator{ 
    function createFeed(){ 
        $feed="<?xml version=\"1.0\" encoding=\"".$this->encoding."\"?>\n"; 
        $feed.= $this->_createGeneratorComment(); 
        if($this->cssStyleSheet==""){ 
            $cssStyleSheet="http://www.w3.org/2000/08/w3c-synd/style.css"; 
        } 
        $feed.= $this->_createStylesheetReferences(); 
        $feed.= "<rdf:RDF\n"; 
        $feed.= "    xmlns=\"http://purl.org/rss/1.0/\"\n"; 
        $feed.= "    xmlns:rdf=\"http://www.w3.org/1999/02/22-rdf-syntax-ns#\"\n"; 
        $feed.= "    xmlns:slash=\"http://purl.org/rss/1.0/modules/slash/\"\n"; 
        $feed.= "    xmlns:dc=\"http://purl.org/dc/elements/1.1/\">\n"; 
        $feed.= "    <channel rdf:about=\"".$this->syndicationURL."\">\n"; 
        $feed.= "        <title>".htmlspecialchars($this->title)."</title>\n"; 
        $feed.= "        <description>".htmlspecialchars($this->description)."</description>\n"; 
        $feed.= "        <link>".$this->link."</link>\n"; 
        if($this->image!=null){ 
            $feed.= "        <image rdf:resource=\"".$this->image->url."\" />\n"; 
        } 
        $now=new FeedDate(); 
        $feed.= "       <dc:date>".htmlspecialchars($now->iso8601())."</dc:date>\n"; 
        $feed.= "        <items>\n"; 
        $feed.= "            <rdf:Seq>\n"; 
        for ($i=0;$i<count($this->items);$i++){ 
            $feed.= "                <rdf:li rdf:resource=\"".htmlspecialchars($this->items[$i]->link)."\"/>\n"; 
        } 
        $feed.= "            </rdf:Seq>\n"; 
        $feed.= "        </items>\n"; 
        $feed.= "    </channel>\n"; 
        if($this->image!=null){ 
            $feed.= "    <image rdf:about=\"".$this->image->url."\">\n"; 
            $feed.= "        <title>".$this->image->title."</title>\n"; 
            $feed.= "        <link>".$this->image->link."</link>\n"; 
            $feed.= "        <url>".$this->image->url."</url>\n"; 
            $feed.= "    </image>\n"; 
        } 
        $feed.= $this->_createAdditionalElements($this->additionalElements,"    "); 
 
        for ($i=0;$i<count($this->items);$i++){ 
            $feed.= "    <item rdf:about=\"".htmlspecialchars($this->items[$i]->link)."\">\n"; 
            //$feed.= "        <dc:type>Posting</dc:type>\n"; 
            $feed.= "        <dc:format>text/html</dc:format>\n"; 
            if($this->items[$i]->date!=null){ 
                $itemDate=new FeedDate($this->items[$i]->date); 
                $feed.= "        <dc:date>".htmlspecialchars($itemDate->iso8601())."</dc:date>\n"; 
            } 
            if($this->items[$i]->source!=""){ 
                $feed.= "        <dc:source>".htmlspecialchars($this->items[$i]->source)."</dc:source>\n"; 
            } 
            if($this->items[$i]->author!=""){ 
                $feed.= "        <dc:creator>".htmlspecialchars($this->items[$i]->author)."</dc:creator>\n"; 
            } 
            $feed.= "        <title>".htmlspecialchars(strip_tags(strtr($this->items[$i]->title,"\n\r","  ")))."</title>\n"; 
            $feed.= "        <link>".htmlspecialchars($this->items[$i]->link)."</link>\n"; 
            $feed.= "        <description>".htmlspecialchars($this->items[$i]->description)."</description>\n"; 
            $feed.= $this->_createAdditionalElements($this->items[$i]->additionalElements,"        "); 
            $feed.= "    </item>\n"; 
        } 
        $feed.= "</rdf:RDF>\n"; 
        return $feed; 
    } 
} 
 
class RSSCreator091 extends FeedCreator{ 
    var $RSSVersion; 
 
    function RSSCreator091(){ 
        $this->_setRSSVersion("0.91"); 
        $this->contentType="application/rss+xml"; 
    } 
 
    function _setRSSVersion($version){ 
        $this->RSSVersion=$version; 
    } 
 
    function createFeed(){ 
        $feed="<?xml version=\"1.0\" encoding=\"".$this->encoding."\"?>\n"; 
        $feed.= $this->_createGeneratorComment(); 
        $feed.= $this->_createStylesheetReferences(); 
        $feed.= "<rss version=\"".$this->RSSVersion."\">\n"; 
        $feed.= "    <channel>\n"; 
        $feed.= "        <title>".FeedCreator::iTrunc(htmlspecialchars($this->title),100)."</title>\n"; 
        $this->descriptionTruncSize=500; 
        $feed.= "        <description>".$this->getDescription()."</description>\n"; 
        $feed.= "        <link>".$this->link."</link>\n"; 
        $now=new FeedDate(); 
        $feed.= "        <lastBuildDate>".htmlspecialchars($now->rfc822())."</lastBuildDate>\n"; 
        $feed.= "        <generator>".FEEDCREATOR_VERSION."</generator>\n"; 
 
        if($this->image!=null){ 
            $feed.= "        <image>\n"; 
            $feed.= "            <url>".$this->image->url."</url>\n"; 
            $feed.= "            <title>".FeedCreator::iTrunc(htmlspecialchars($this->image->title),100)."</title>\n"; 
            $feed.= "            <link>".$this->image->link."</link>\n"; 
            if($this->image->width!=""){ 
                $feed.= "            <width>".$this->image->width."</width>\n"; 
            } 
            if($this->image->height!=""){ 
                $feed.= "            <height>".$this->image->height."</height>\n"; 
            } 
            if($this->image->description!=""){ 
                $feed.= "            <description>".$this->image->getDescription()."</description>\n"; 
            } 
            $feed.= "        </image>\n"; 
        } 
        if($this->language!=""){ 
            $feed.= "        <language>".$this->language."</language>\n"; 
        } 
        if($this->copyright!=""){ 
            $feed.= "        <copyright>".FeedCreator::iTrunc(htmlspecialchars($this->copyright),100)."</copyright>\n"; 
        } 
        if($this->editor!=""){ 
            $feed.= "        <managingEditor>".FeedCreator::iTrunc(htmlspecialchars($this->editor),100)."</managingEditor>\n"; 
        } 
        if($this->webmaster!=""){ 
            $feed.= "        <webMaster>".FeedCreator::iTrunc(htmlspecialchars($this->webmaster),100)."</webMaster>\n"; 
        } 
        if($this->pubDate!=""){ 
            $pubDate=new FeedDate($this->pubDate); 
            $feed.= "        <pubDate>".htmlspecialchars($pubDate->rfc822())."</pubDate>\n"; 
        } 
        if($this->category!=""){ 
            $feed.= "        <category>".htmlspecialchars($this->category)."</category>\n"; 
        } 
        if($this->docs!=""){ 
            $feed.= "        <docs>".FeedCreator::iTrunc(htmlspecialchars($this->docs),500)."</docs>\n"; 
        } 
        if($this->ttl!=""){ 
            $feed.= "        <ttl>".htmlspecialchars($this->ttl)."</ttl>\n"; 
        } 
        if($this->rating!=""){ 
            $feed.= "        <rating>".FeedCreator::iTrunc(htmlspecialchars($this->rating),500)."</rating>\n"; 
        } 
        if($this->skipHours!=""){ 
            $feed.= "        <skipHours>".htmlspecialchars($this->skipHours)."</skipHours>\n"; 
        } 
        if($this->skipDays!=""){ 
            $feed.= "        <skipDays>".htmlspecialchars($this->skipDays)."</skipDays>\n"; 
        } 
        $feed.= $this->_createAdditionalElements($this->additionalElements,"    "); 
 
        for ($i=0;$i<count($this->items);$i++){ 
            $feed.= "        <item>\n"; 
            $feed.= "            <title>".FeedCreator::iTrunc(htmlspecialchars(strip_tags($this->items[$i]->title)),100)."</title>\n"; 
            $feed.= "            <link>".htmlspecialchars($this->items[$i]->link)."</link>\n"; 
            $feed.= "            <description>".$this->items[$i]->getDescription()."</description>\n"; 
 
            if($this->items[$i]->author!=""){ 
                $feed.= "            <author>".htmlspecialchars($this->items[$i]->author)."</author>\n"; 
            } 
            /* 
             // on hold 
             if($this->items[$i]->source!=""){ 
             $feed.= "            <source>".htmlspecialchars($this->items[$i]->source)."</source>\n"; 
             } 
             */ 
            if($this->items[$i]->category!=""){ 
                $feed.= "            <category>".htmlspecialchars($this->items[$i]->category)."</category>\n"; 
            } 
            if($this->items[$i]->comments!=""){ 
                $feed.= "            <comments>".htmlspecialchars($this->items[$i]->comments)."</comments>\n"; 
            } 
            if($this->items[$i]->date!=""){ 
                $itemDate=new FeedDate($this->items[$i]->date); 
                $feed.= "            <pubDate>".htmlspecialchars($itemDate->rfc822())."</pubDate>\n"; 
            } 
            if($this->items[$i]->guid!=""){ 
                $feed.= "            <guid>".htmlspecialchars($this->items[$i]->guid)."</guid>\n"; 
            } 
            $feed.= $this->_createAdditionalElements($this->items[$i]->additionalElements,"        "); 
            $feed.= "        </item>\n"; 
        } 
        $feed.= "    </channel>\n"; 
        $feed.= "</rss>\n"; 
        return $feed; 
    } 
} 
 
class RSSCreator20 extends RSSCreator091{ 
 
    function RSSCreator20(){ 
        parent::_setRSSVersion("2.0"); 
    } 
}

使用示例：

代码如下:

<?php 
header(&#39;Content-Type:text/html; charset=utf-8&#39;); 
$db=mysql_connect(&#39;127.0.0.1&#39;,&#39;root&#39;,&#39;123456&#39;); 
mysql_query("set names utf8"); 
mysql_select_db(&#39;dbname&#39;,$db); 
$brs=mysql_query(&#39;select * from article order by add_time desc limit 0,10&#39;,$db); 
$rss=new UniversalFeedCreator(); 
$rss->title="页面标题"; 
$rss->link="网址http://"; 
$rss->description="rss标题"; 
while($rowbrs=mysql_fetch_array($brs)){ 
    $item=new FeedItem(); 
    $item->title =$rowbrs[&#39;subject&#39;]; 
    $item->link=&#39;//www.jb51.net/&#39;; 
    $item->description =$rowbrs[&#39;description&#39;]; 
    $rss->addItem($item); 
} 
mysql_close($db); 
$rss->saveFeed("RSS2.0","rss.xml");

总结：以上就是本篇文的全部内容，希望能对大家的学习有所帮助。

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