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>脚本之家</title>
<link>https://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>
复制代码 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=https://www.jb51.net/article/\"".FEEDCREATOR_VERSION."https://www.jb51.net/article/\" -->\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) $xml .= "<?xml-stylesheet href=https://www.jb51.net/article/\"".$this->cssStyleSheet."https://www.jb51.net/article/\" type=https://www.jb51.net/article/\"text/css\"?>\n";
if($this->xslStyleSheet) $xml .= "<?xml-stylesheet href=https://www.jb51.net/article/\"".$this->xslStyleSheet."https://www.jb51.net/article/\" type=https://www.jb51.net/article/\"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($matches[7],0,1)=='+' OR substr($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(){
$feed="<?xml version=https://www.jb51.net/article/\"1.0\" encoding=https://www.jb51.net/article/\"".$this->encoding."https://www.jb51.net/article/\"?>\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=https://www.jb51.net/article/\"http://purl.org/rss/1.0/\"\n";
$feed.= " xmlns:rdf=https://www.jb51.net/article/\"http://www.w3.org/1999/02/22-rdf-syntax-ns#\"\n";
$feed.= " xmlns:slash=https://www.jb51.net/article/\"http://purl.org/rss/1.0/modules/slash/\"\n";
$feed.= " xmlns:dc=https://www.jb51.net/article/\"http://purl.org/dc/elements/1.1/\">\n";
$feed.= " <channel rdf:about=https://www.jb51.net/article/\"".$this->syndicationURL."https://www.jb51.net/article/\">\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){
$feed.= " <image rdf:resource=https://www.jb51.net/article/\"".$this->image->url."https://www.jb51.net/article/\" />\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++){
$feed.= " <rdf:li rdf:resource=https://www.jb51.net/article/\"".htmlspecialchars($this->items[$i]->link)."https://www.jb51.net/article/\"/>\n";
}
$feed.= " </rdf:Seq>\n";
$feed.= " </items>\n";
$feed.= " </channel>\n";
if($this->image!=null){
$feed.= " <image rdf:about=https://www.jb51.net/article/\"".$this->image->url."https://www.jb51.net/article/\">\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++){
$feed.= " <item rdf:about=https://www.jb51.net/article/\"".htmlspecialchars($this->items[$i]->link)."https://www.jb51.net/article/\">\n";
//$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(){
$feed="<?xml version=https://www.jb51.net/article/\"1.0\" encoding=https://www.jb51.net/article/\"".$this->encoding."https://www.jb51.net/article/\"?>\n";
$feed.= $this->_createGeneratorComment();
$feed.= $this->_createStylesheetReferences();
$feed.= "<rss version=https://www.jb51.net/article/\"".$this->RSSVersion."https://www.jb51.net/article/\">\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：
复制代码 代码如下: