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：

代码如下:

<?xml version="1.0" encoding="utf-8"?>

<rss version="2.0">

<channel>

<title>脚本之家</title>

<link>http://www.jb51.net/</link>

<description>脚本之家</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","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+)?()){

$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("~()){

$this->unix=mktime($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."\"?>\n";

$feed.= $this->_createGeneratorComment();

if($this->cssStyleSheet==""){

$cssStyleSheet="";

}

$feed.= $this->_createStylesheetReferences();

$feed.= "<rdf:RDF\n";

$feed.= " xmlns=\"";

$feed.= " xmlns:rdf=\"";

$feed.= " xmlns:slash=\"";

$feed.= " xmlns:dc=\"";

$feed.= " <channel rdf:about=\"".$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('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='http://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。

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