RSS Reader is used to read RSS feeds.
AJAX RSS Reader
In the following example, we will demonstrate an RSS reader through which the content from RSS is The web page is loaded without refreshing:
Select an RSS-feed:
Read RSS data
RSS-feed data list...
Example explanation - HTML page
When the user selects an RSS-feed in the drop-down list above, the command named " showRSS()" function. This function is triggered by the "onchange" event:
<html>
<head>
<meta charset="utf-8">
<title>php中文网(php.cn)</title>
<script>
function showRSS(str)
{
if (str.length==0)
{
document.getElementById("rssOutput").innerHTML="";
return;
}
if (window.XMLHttpRequest)
{
// IE7+, Firefox, Chrome, Opera, Safari 浏览器执行代码
xmlhttp=new XMLHttpRequest();
}
else
{
// IE6, IE5 浏览器执行代码
xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
}
xmlhttp.onreadystatechange=function()
{
if (xmlhttp.readyState==4 && xmlhttp.status==200)
{
document.getElementById("rssOutput").innerHTML=xmlhttp.responseText;
}
}
xmlhttp.open("GET","getrss.php?q="+str,true);
xmlhttp.send();
}
</script>
</head>
<body>
<form>
<select onchange="showRSS(this.value)">
<option value="">选择一个 RSS-feed:</option>
<option value="rss">读取 RSS 数据</option>
</select>
</form>
<br>
<div id="rssOutput">RSS-feed 数据列表...</div>
</body>
</html>showRSS() function will perform the following steps:
Check whether an RSS-feed is selected
1) Create an XMLHttpRequest object
2) Create a function that executes when the server response is ready
3) Send a request to a file on the server
4) Please note the parameters added to the end of the URL (q ) (contains the contents of the drop-down list)
PHP file
File rss_demo.xml.
The server page called through JavaScript in the above paragraph is a PHP file named "getrss.php":
<?php
// rss 文件
$xml="rss_demo.xml";
$xmlDoc = new DOMDocument();
$xmlDoc->load($xml);
// 从 "<channel>" 中读取元素
$channel=$xmlDoc->getElementsByTagName('channel')->item(0);
$channel_title = $channel->getElementsByTagName('title')
->item(0)->childNodes->item(0)->nodeValue;
$channel_link = $channel->getElementsByTagName('link')
->item(0)->childNodes->item(0)->nodeValue;
$channel_desc = $channel->getElementsByTagName('description')
->item(0)->childNodes->item(0)->nodeValue;
// 输出 "<channel>" 中的元素
echo("<p><a href='" . $channel_link
. "'>" . $channel_title . "</a>");
echo("<br>");
echo($channel_desc . "</p>");
// 输出 "<item>" 中的元素
$x=$xmlDoc->getElementsByTagName('item');
for ($i=0; $i<=1; $i++) {
$item_title=$x->item($i)->getElementsByTagName('title')
->item(0)->childNodes->item(0)->nodeValue;
$item_link=$x->item($i)->getElementsByTagName('link')
->item(0)->childNodes->item(0)->nodeValue;
$item_desc=$x->item($i)->getElementsByTagName('description')
->item(0)->childNodes->item(0)->nodeValue;
echo ("<p><a href='" . $item_link
. "'>" . $item_title . "</a>");
echo ("<br>");
echo ($item_desc . "</p>");
}
?>When the request for the RSS feed is sent from JavaScript to the PHP file, what will happen is:
1) Check which RSS feed is selected
2) Create a new XML DOM object
3) Load the RSS document in the xml variable
4) Extract and output the element
from the channel element 5) Extract and output the element
from the item element
Next Section