php生成RSS订阅的方法

2020-03-22 17:33:39

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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：
复制代码代码如下: xml version="1.0" encoding="utf-8"
rss version="2.0"
channel
title phpstudy /title
link http://www.phpstudy.net/ /link
description phpstudy /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.phpstudy.net");//您的网址
html' target='_blank'>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"=
$this- unix=mktime($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/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//"
$feed.= " channel rdf:about=/"".$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,"/n/r"," ")))." /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='http://www.phpstudy.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。PHP教程

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