php生成RSS订阅的方法

本文实例讲述了php生成RSS订阅的方法。分享给大家供大家参考。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：复制代码 代码如下:<?xml version="1.0" encoding="utf-8"?> <rss version="2.0"> <channel> <title>网页设计</title> <link>//www.rzxsoft.cn/</link> <description>网页设计</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：复制代码 代码如下:<?php /** ** php 动态生成 RSS 类 **/ define("TIME_ZONE",""); define("FEEDCREATOR_VERSION","www.rzxsoft.cn");//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."" -->";     }      function _createAdditionalElements($elements,$indentString=""){         $ae="";         if(is_array($elements)){             foreach($elements AS $key => $value){                 $ae.= $indentString."<$key>$value</$key>";             }         }         return $ae;     }      function _createStylesheetReferences(){         $xml="";         if($this->cssStyleSheet) $xml .= "<?xml-stylesheet href="".$this->cssStyleSheet."" type="text/css"?>";         if($this->xslStyleSheet) $xml .= "<?xml-stylesheet href="".$this->xslStyleSheet."" type="text/xsl"?>";         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($matches[7],0,1)=="+" OR substr($matches[7],0,1)=="-"){                 $tzOffset=(substr($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)=="+" OR substr($matches[7],0,1)=="-"){                 $tzOffset=(substr($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) . ":" . 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.""?>";         $feed.= $this->_createGeneratorComment();         if($this->cssStyleSheet==""){             $cssStyleSheet="http://www.w3.org/2000/08/w3c-synd/style.css";         }         $feed.= $this->_createStylesheetReferences();         $feed.= "<rdf:RDF";         $feed.= "    xmlns="http://purl.org/rss/1.0/"";         $feed.= "    xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"";         $feed.= "    xmlns:slash="http://purl.org/rss/1.0/modules/slash/"";         $feed.= "    xmlns:dc="http://purl.org/dc/elements/1.1/">";         $feed.= "    <channel rdf:about="".$this->syndicationURL."">";         $feed.= "        <title>".htmlspecialchars($this->title)."</title>";         $feed.= "        <description>".htmlspecialchars($this->description)."</description>";         $feed.= "        <link>".$this->link."</link>";         if($this->image!=null){             $feed.= "        <image rdf:resource="".$this->image->url."" />";         }         $now=new FeedDate();         $feed.= "       <dc:date>".htmlspecialchars($now->iso8601())."</dc:date>";         $feed.= "        <items>";         $feed.= "            <rdf:Seq>";         for ($i=0;$i<count($this->items);$i++){             $feed.= "                <rdf:li rdf:resource="".htmlspecialchars($this->items[$i]->link).""/>";         }         $feed.= "            </rdf:Seq>";         $feed.= "        </items>";         $feed.= "    </channel>";         if($this->image!=null){             $feed.= "    <image rdf:about="".$this->image->url."">";             $feed.= "        <title>".$this->image->title."</title>";             $feed.= "        <link>".$this->image->link."</link>";             $feed.= "        <url>".$this->image->url."</url>";             $feed.= "    </image>";         }         $feed.= $this->_createAdditionalElements($this->additionalElements,"    ");          for ($i=0;$i<count($this->items);$i++){             $feed.= "    <item rdf:about="".htmlspecialchars($this->items[$i]->link)."">";             //$feed.= "        <dc:type>Posting</dc:type>";             $feed.= "        <dc:format>text/html</dc:format>";             if($this->items[$i]->date!=null){                 $itemDate=new FeedDate($this->items[$i]->date);                 $feed.= "        <dc:date>".htmlspecialchars($itemDate->iso8601())."</dc:date>";             }             if($this->items[$i]->source!=""){                 $feed.= "        <dc:source>".htmlspecialchars($this->items[$i]->source)."</dc:source>";             }             if($this->items[$i]->author!=""){                 $feed.= "        <dc:creator>".htmlspecialchars($this->items[$i]->author)."</dc:creator>";             }             $feed.= "        <title>".htmlspecialchars(strip_tags(strtr($this->items[$i]->title,"","  ")))."</title>";             $feed.= "        <link>".htmlspecialchars($this->items[$i]->link)."</link>";             $feed.= "        <description>".htmlspecialchars($this->items[$i]->description)."</description>";             $feed.= $this->_createAdditionalElements($this->items[$i]->additionalElements,"        ");             $feed.= "    </item>";         }         $feed.= "</rdf:RDF>";         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.""?>";         $feed.= $this->_createGeneratorComment();         $feed.= $this->_createStylesheetReferences();         $feed.= "<rss version="".$this->RSSVersion."">";         $feed.= "    <channel>";         $feed.= "        <title>".FeedCreator::iTrunc(htmlspecialchars($this->title),100)."</title>";         $this->descriptionTruncSize=500;         $feed.= "        <description>".$this->getDescription()."</description>";         $feed.= "        <link>".$this->link."</link>";         $now=new FeedDate();         $feed.= "        <lastBuildDate>".htmlspecialchars($now->rfc822())."</lastBuildDate>";         $feed.= "        <generator>".FEEDCREATOR_VERSION."</generator>";          if($this->image!=null){             $feed.= "        <image>";             $feed.= "            <url>".$this->image->url."</url>";             $feed.= "            <title>".FeedCreator::iTrunc(htmlspecialchars($this->image->title),100)."</title>";             $feed.= "            <link>".$this->image->link."</link>";             if($this->image->width!=""){                 $feed.= "            <width>".$this->image->width."</width>";             }             if($this->image->height!=""){                 $feed.= "            <height>".$this->image->height."</height>";             }             if($this->image->description!=""){                 $feed.= "            <description>".$this->image->getDescription()."</description>";             }             $feed.= "        </image>";         }         if($this->language!=""){             $feed.= "        <language>".$this->language."</language>";         }         if($this->copyright!=""){             $feed.= "        <copyright>".FeedCreator::iTrunc(htmlspecialchars($this->copyright),100)."</copyright>";         }         if($this->editor!=""){             $feed.= "        <managingEditor>".FeedCreator::iTrunc(htmlspecialchars($this->editor),100)."</managingEditor>";         }         if($this->webmaster!=""){             $feed.= "        <webMaster>".FeedCreator::iTrunc(htmlspecialchars($this->webmaster),100)."</webMaster>";         }         if($this->pubDate!=""){             $pubDate=new FeedDate($this->pubDate);             $feed.= "        <pubDate>".htmlspecialchars($pubDate->rfc822())."</pubDate>";         }         if($this->category!=""){             $feed.= "        <category>".htmlspecialchars($this->category)."</category>";         }         if($this->docs!=""){             $feed.= "        <docs>".FeedCreator::iTrunc(htmlspecialchars($this->docs),500)."</docs>";         }         if($this->ttl!=""){             $feed.= "        <ttl>".htmlspecialchars($this->ttl)."</ttl>";         }         if($this->rating!=""){             $feed.= "        <rating>".FeedCreator::iTrunc(htmlspecialchars($this->rating),500)."</rating>";         }         if($this->skipHours!=""){             $feed.= "        <skipHours>".htmlspecialchars($this->skipHours)."</skipHours>";         }         if($this->skipDays!=""){             $feed.= "        <skipDays>".htmlspecialchars($this->skipDays)."</skipDays>";         }         $feed.= $this->_createAdditionalElements($this->additionalElements,"    ");          for ($i=0;$i<count($this->items);$i++){             $feed.= "        <item>";             $feed.= "            <title>".FeedCreator::iTrunc(htmlspecialchars(strip_tags($this->items[$i]->title)),100)."</title>";             $feed.= "            <link>".htmlspecialchars($this->items[$i]->link)."</link>";             $feed.= "            <description>".$this->items[$i]->getDescription()."</description>";              if($this->items[$i]->author!=""){                 $feed.= "            <author>".htmlspecialchars($this->items[$i]->author)."</author>";             }             /*              // on hold              if($this->items[$i]->source!=""){              $feed.= "            <source>".htmlspecialchars($this->items[$i]->source)."</source>";              }              */             if($this->items[$i]->category!=""){                 $feed.= "            <category>".htmlspecialchars($this->items[$i]->category)."</category>";             }             if($this->items[$i]->comments!=""){                 $feed.= "            <comments>".htmlspecialchars($this->items[$i]->comments)."</comments>";             }             if($this->items[$i]->date!=""){                 $itemDate=new FeedDate($this->items[$i]->date);                 $feed.= "            <pubDate>".htmlspecialchars($itemDate->rfc822())."</pubDate>";             }             if($this->items[$i]->guid!=""){                 $feed.= "            <guid>".htmlspecialchars($this->items[$i]->guid)."</guid>";             }             $feed.= $this->_createAdditionalElements($this->items[$i]->additionalElements,"        ");             $feed.= "        </item>";         }         $feed.= "    </channel>";         $feed.= "</rss>";         return $feed;     } }  class RSSCreator20 extends RSSCreator091{      function RSSCreator20(){         parent::_setRSSVersion("2.0");     } }使用示例：复制代码 代码如下:<?php header("Content-Type:text/html; charset=utf-8"); $db=mysql_connect("127.0.0.1","root","123456"); mysql_query("set names utf8"); mysql_select_db("dbname",$db); $brs=mysql_query("select * from article order by add_time desc limit 0,10",$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["subject"];     $item->link="//www.rzxsoft.cn/";     $item->description =$rowbrs["description"];     $rss->addItem($item); } mysql_close($db); $rss->saveFeed("RSS2.0","rss.xml");

希望本文所述对大家的php程序设计有所帮助。