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:



https://www.jb51.net/
考高分网


网站地址/rss
New RSS tutorial on W3School



网站地址/xml
New XML tutorial on W3School

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:
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){
            $result="rawFieldContent."]]>";
        }else{
            if($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 "n";
    }
 
    function _createAdditionalElements($elements,$indentString=""){
        $ae="";
        if(is_array($elements)){
            foreach($elements AS $key => $value){
                $ae.= $indentString."<$key>$valuen";
            }
        }
        return $ae;
    }
 
    function _createStylesheetReferences(){
        $xml="";
        if($this->cssStyleSheet) $xml .= "cssStyleSheet."" type="text/css"?>n";
        if($this->xslStyleSheet) $xml .= "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 "
Error creating feed file, please check write permissions.
";
        }
    }
}
 
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="encoding.""?>n";
        $feed.= $this->_createGeneratorComment();
        if($this->cssStyleSheet==""){
            $cssStyleSheet="http://www.w3.org/2000/08/w3c-synd/style.css";
        }
        $feed.= $this->_createStylesheetReferences();
        $feed.= "         $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.= "    syndicationURL."">n";
        $feed.= "        n";
        $feed.= "        ".htmlspecialchars($this->description)."n";
        $feed.= "        ".$this->link."n";
        if($this->image!=null){
            $feed.= "        image->url."" />n";
        }
        $now=new FeedDate();
        $feed.= "       ".htmlspecialchars($now->iso8601())."n";
        $feed.= "        n";
        $feed.= "            n";
        for ($i=0;$iitems);$i++){
            $feed.= "                items[$i]->link).""/>n";
        }
        $feed.= "            n";
        $feed.= "        n";
        $feed.= "    n";
        if($this->image!=null){
            $feed.= "    image->url."">n";
            $feed.= "        n";
            $feed.= "        ".$this->image->link."n";
            $feed.= "        ".$this->image->url."n";
            $feed.= "    n";
        }
        $feed.= $this->_createAdditionalElements($this->additionalElements,"    ");
 
        for ($i=0;$iitems);$i++){
            $feed.= "    items[$i]->link)."">n";
            //$feed.= "        Postingn";
            $feed.= "        text/htmln";
            if($this->items[$i]->date!=null){
                $itemDate=new FeedDate($this->items[$i]->date);
                $feed.= "        ".htmlspecialchars($itemDate->iso8601())."n";
            }
            if($this->items[$i]->source!=""){
                $feed.= "        ".htmlspecialchars($this->items[$i]->source)."n";
            }
            if($this->items[$i]->author!=""){
                $feed.= "        ".htmlspecialchars($this->items[$i]->author)."n";
            }
            $feed.= "        n";
            $feed.= "        ".htmlspecialchars($this->items[$i]->link)."n";
            $feed.= "        ".htmlspecialchars($this->items[$i]->description)."n";
            $feed.= $this->_createAdditionalElements($this->items[$i]->additionalElements,"        ");
            $feed.= "    n";
        }
        $feed.= "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="encoding.""?>n";
        $feed.= $this->_createGeneratorComment();
        $feed.= $this->_createStylesheetReferences();
        $feed.= "RSSVersion."">n";
        $feed.= "    n";
        $feed.= "        n";
        $this->descriptionTruncSize=500;
        $feed.= "        ".$this->getDescription()."n";
        $feed.= "        ".$this->link."n";
        $now=new FeedDate();
        $feed.= "        ".htmlspecialchars($now->rfc822())."n";
        $feed.= "        ".FEEDCREATOR_VERSION."n";
 
        if($this->image!=null){
            $feed.= "        n";
            $feed.= "            ".$this->image->url."n";
            $feed.= "            n";
            $feed.= "            ".$this->image->link."n";
            if($this->image->width!=""){
                $feed.= "            ".$this->image->width."n";
            }
            if($this->image->height!=""){
                $feed.= "            ".$this->image->height."n";
            }
            if($this->image->description!=""){
                $feed.= "            ".$this->image->getDescription()."n";
            }
            $feed.= "        n";
        }
        if($this->language!=""){
            $feed.= "        ".$this->language."n";
        }
        if($this->copyright!=""){
            $feed.= "        ".FeedCreator::iTrunc(htmlspecialchars($this->copyright),100)."n";
        }
        if($this->editor!=""){
            $feed.= "        ".FeedCreator::iTrunc(htmlspecialchars($this->editor),100)."n";
        }
        if($this->webmaster!=""){
            $feed.= "        ".FeedCreator::iTrunc(htmlspecialchars($this->webmaster),100)."n";
        }
        if($this->pubDate!=""){
            $pubDate=new FeedDate($this->pubDate);
            $feed.= "        ".htmlspecialchars($pubDate->rfc822())."n";
        }
        if($this->category!=""){
            $feed.= "        ".htmlspecialchars($this->category)."n";
        }
        if($this->docs!=""){
            $feed.= "        ".FeedCreator::iTrunc(htmlspecialchars($this->docs),500)."n";
        }
        if($this->ttl!=""){
            $feed.= "        ".htmlspecialchars($this->ttl)."n";
        }
        if($this->rating!=""){
            $feed.= "        ".FeedCreator::iTrunc(htmlspecialchars($this->rating),500)."n";
        }
        if($this->skipHours!=""){
            $feed.= "        ".htmlspecialchars($this->skipHours)."n";
        }
        if($this->skipDays!=""){
            $feed.= "        ".htmlspecialchars($this->skipDays)."n";
        }
        $feed.= $this->_createAdditionalElements($this->additionalElements,"    ");
 
        for ($i=0;$iitems);$i++){
            $feed.= "        n";
            $feed.= "            n";
            $feed.= "            ".htmlspecialchars($this->items[$i]->link)."n";
            $feed.= "            ".$this->items[$i]->getDescription()."n";
 
            if($this->items[$i]->author!=""){
                $feed.= "            ".htmlspecialchars($this->items[$i]->author)."n";
            }
           
            if($this->items[$i]->category!=""){
                $feed.= "            ".htmlspecialchars($this->items[$i]->category)."n";
            }
            if($this->items[$i]->comments!=""){
                $feed.= "            ".htmlspecialchars($this->items[$i]->comments)."n";
            }
            if($this->items[$i]->date!=""){
                $itemDate=new FeedDate($this->items[$i]->date);
                $feed.= "            ".htmlspecialchars($itemDate->rfc822())."n";
            }
            if($this->items[$i]->guid!=""){
                $feed.= "            ".htmlspecialchars($this->items[$i]->guid)."n";
            }
            $feed.= $this->_createAdditionalElements($this->items[$i]->additionalElements,"        ");
            $feed.= "        n";
        }
        $feed.= "    n";
        $feed.= "n";
        return $feed;
    }
}
 
class RSSCreator20 extends RSSCreator091{
 
    function RSSCreator20(){
        parent::_setRSSVersion("2.0");
    }
}
使用示例：
复制代码 代码如下: 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='https://www.jb51.net/';
    $item->description =$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。