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:
代码如下:
http://www.jb51.net/
网站地址/rss
网站地址/xml
下面分享一段使用 php 动态生成 RSS 的代码示例:
代码如下:
/**
** 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){
$result="rawFieldContent."]]>";
}else{
if($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)
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.= $indentString."$value$key>\n";
}
}
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)
$this->_redirect($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
$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: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.= "
$feed.= "
$feed.= "
$feed.= " ".$this->link."\n";
if($this->image!=null){
$feed.= "
}
$now=new FeedDate();
$feed.= "
$feed.= "
$feed.= "
for ($i=0;$i
$feed.= "
}
$feed.= "
$feed.= "
$feed.= "
if($this->image!=null){
$feed.= "
$feed.= "
$feed.= " ".$this->image->link."\n";
$feed.= "
$feed.= "
}
$feed.= $this->_createAdditionalElements($this->additionalElements," ");
for ($i=0;$i
$feed.= "
//$feed.= "
$feed.= "
if($this->items[$i]->date!=null){
$itemDate=new FeedDate($this->items[$i]->date);
$feed.= "
}
if($this->items[$i]->source!=""){
$feed.= "
}
if($this->items[$i]->author!=""){
$feed.= "
}
$feed.= "
$feed.= " ".htmlspecialchars($this->items[$i]->link)."\n";
$feed.= "
$feed.= $this->_createAdditionalElements($this->items[$i]->additionalElements," ");
$feed.= "
}
$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.= "
$feed.= "
$feed.= "
$this->descriptionTruncSize=500;
$feed.= "
$feed.= " ".$this->link."\n";
$now=new FeedDate();
$feed.= "
$feed.= "
if($this->image!=null){
$feed.= "
$feed.= "
$feed.= "
$feed.= " ".$this->image->link."\n";
if($this->image->width!=""){
$feed.= "
}
if($this->image->height!=""){
$feed.= "
}
if($this->image->description!=""){
$feed.= "
}
$feed.= "
}
if($this->language!=""){
$feed.= "
}
if($this->copyright!=""){
$feed.= "
}
if($this->editor!=""){
$feed.= "
}
if($this->webmaster!=""){
$feed.= "
}
if($this->pubDate!=""){
$pubDate=new FeedDate($this->pubDate);
$feed.= "
}
if($this->category!=""){
$feed.= "
}
if($this->docs!=""){
$feed.= "
}
if($this->ttl!=""){
$feed.= "
}
if($this->rating!=""){
$feed.= "
}
if($this->skipHours!=""){
$feed.= "
}
if($this->skipDays!=""){
$feed.= "
}
$feed.= $this->_createAdditionalElements($this->additionalElements," ");
for ($i=0;$i
$feed.= "
$feed.= "
$feed.= " ".htmlspecialchars($this->items[$i]->link)."\n";
$feed.= "
if($this->items[$i]->author!=""){
$feed.= "
}
/*
// on hold
if($this->items[$i]->source!=""){
$feed.= "
}
*/
if($this->items[$i]->category!=""){
$feed.= "
}
if($this->items[$i]->comments!=""){
$feed.= "
}
if($this->items[$i]->date!=""){
$itemDate=new FeedDate($this->items[$i]->date);
$feed.= "
}
if($this->items[$i]->guid!=""){
$feed.= "
}
$feed.= $this->_createAdditionalElements($this->items[$i]->additionalElements," ");
$feed.= "
}
$feed.= "
$feed.= "
return $feed;
}
}
class RSSCreator20 extends RSSCreator091{
function RSSCreator20(){
parent::_setRSSVersion("2.0");
}
}
使用示例:
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='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。

php把负数转为正整数的方法:1、使用abs()函数将负数转为正数,使用intval()函数对正数取整,转为正整数,语法“intval(abs($number))”;2、利用“~”位运算符将负数取反加一,语法“~$number + 1”。

实现方法:1、使用“sleep(延迟秒数)”语句,可延迟执行函数若干秒;2、使用“time_nanosleep(延迟秒数,延迟纳秒数)”语句,可延迟执行函数若干秒和纳秒;3、使用“time_sleep_until(time()+7)”语句。

php除以100保留两位小数的方法:1、利用“/”运算符进行除法运算,语法“数值 / 100”;2、使用“number_format(除法结果, 2)”或“sprintf("%.2f",除法结果)”语句进行四舍五入的处理值,并保留两位小数。

判断方法:1、使用“strtotime("年-月-日")”语句将给定的年月日转换为时间戳格式;2、用“date("z",时间戳)+1”语句计算指定时间戳是一年的第几天。date()返回的天数是从0开始计算的,因此真实天数需要在此基础上加1。

php判断有没有小数点的方法:1、使用“strpos(数字字符串,'.')”语法,如果返回小数点在字符串中第一次出现的位置,则有小数点;2、使用“strrpos(数字字符串,'.')”语句,如果返回小数点在字符串中最后一次出现的位置,则有。

方法:1、用“str_replace(" ","其他字符",$str)”语句,可将nbsp符替换为其他字符;2、用“preg_replace("/(\s|\ \;||\xc2\xa0)/","其他字符",$str)”语句。

php字符串有下标。在PHP中,下标不仅可以应用于数组和对象,还可应用于字符串,利用字符串的下标和中括号“[]”可以访问指定索引位置的字符,并对该字符进行读写,语法“字符串名[下标值]”;字符串的下标值(索引值)只能是整数类型,起始值为0。

在PHP中,可以利用implode()函数的第一个参数来设置没有分隔符,该函数的第一个参数用于规定数组元素之间放置的内容,默认是空字符串,也可将第一个参数设置为空,语法为“implode(数组)”或者“implode("",数组)”。


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