PHP Example - AJAX and XML

AJAX can be used to communicate interactively with XML files.

AJAX XML Example

The following example will demonstrate how a web page reads information from an XML file through AJAX:

QQ图片20161010102948.png

Explanation of examples - HTML page

When the user selects a CD in the drop-down list above, the function named "showCD()" will be executed. This function is triggered by the "onchange" event:

<html>
<head>
<script>
function showCD(str)
{
         if (str=="")
         {
                 document.getElementById("txtHint").innerHTML="";
                 return;
         }
         if (window.XMLHttpRequest)
         {
                 // IE7+, Firefox, Chrome, Opera, Safari 浏览器执行
                 xmlhttp=new XMLHttpRequest();
         }
         else
         {
                 // IE6, IE5 浏览器执行
                 xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
         }
         xmlhttp.onreadystatechange=function()
         {
                 if (xmlhttp.readyState==4 && xmlhttp.status==200)
                 {
                          document.getElementById("txtHint").innerHTML=xmlhttp.responseText;
                 }
         }
         xmlhttp.open("GET","getcd.php?q="+str,true);
         xmlhttp.send();
}
</script>
</head>
<body>
 
<form>
Select a CD:
<select name="cds" onchange="showCD(this.value)">
<option value="">Select a CD:</option>
<option value="Bob Dylan">Bob Dylan</option>
<option value="Bonnie Tyler">Bonnie Tyler</option>
<option value="Dolly Parton">Dolly Parton</option>
</select>
</form>
<div id="txtHint"><b>CD info will be listed here...</b></div>
 
</body>
</html>

The showCD() function will perform the following steps:

##·

· Create a function that executes when the server response is ready Content)

PHP file

The server page called through JavaScript above is a PHP file named "getcd.php".

The PHP script loads the XML document, "cd_catalog.xml", runs the query against the XML file, and returns the results in HTML:

<?php
$q=$_GET["q"];
 
$xmlDoc = new DOMDocument();
$xmlDoc->load("cd_catalog.xml");
 
$x=$xmlDoc->getElementsByTagName('ARTIST');
 
for ($i=0; $i<=$x->length-1; $i++)
{
         // 处理元素节点
         if ($x->item($i)->nodeType==1)
         {
                 if ($x->item($i)->childNodes->item(0)->nodeValue == $q)
                 {
                          $y=($x->item($i)->parentNode);
                 }
         }
}
 
$cd=($y->childNodes);
 
for ($i=0;$i<$cd->length;$i++)
{
         // 处理元素节点
         if ($cd->item($i)->nodeType==1)
         {
                 echo("<b>" . $cd->item($i)->nodeName . ":</b> ");
                 echo($cd->item($i)->childNodes->item(0)->nodeValue);
                 echo("<br>");
         }
}
?>

When the CD query is sent from JavaScript to the PHP page, Occurrence:

1. PHP creates an XML DOM object

2. Finds names in all <artist> elements that match the data passed by JavaScript

Output album information , and sends back the "txtHint" placeholder

Continuing Learning

new file

<html> <head> <script> function showCD(str) { if (str=="") { document.getElementById("txtHint").innerHTML=""; return; } if (window.XMLHttpRequest) { // IE7+, Firefox, Chrome, Opera, Safari 浏览器执行 xmlhttp=new XMLHttpRequest(); } else { // IE6, IE5 浏览器执行 xmlhttp=new ActiveXObject("Microsoft.XMLHTTP"); } xmlhttp.onreadystatechange=function() { if (xmlhttp.readyState==4 && xmlhttp.status==200) { document.getElementById("txtHint").innerHTML=xmlhttp.responseText; } } xmlhttp.open("GET","getcd.php?q="+str,true); xmlhttp.send(); } </script> </head> <body> <form> Select a CD: <select name="cds" onchange="showCD(this.value)"> <option value="">Select a CD:</option> <option value="Bob Dylan">Bob Dylan</option> <option value="Bonnie Tyler">Bonnie Tyler</option> <option value="Dolly Parton">Dolly Parton</option> </select> </form> <div id="txtHint"><b>CD info will be listed here...</b></div> </body> </html>

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