php生成RSS订阅的方法

2024-09-06 20:00:53

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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","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 "/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($matches[7],0,1)=='+' OR substr($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."/"?>/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");
}
}

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