为何PHP不能接收。

 $.ajax({<br />       type: "POST",<br />        url: "index.php",<br />        data: "location=img_png_src",<br />        success: function(msg){<br />         alert( "Data Saved: " + msg );<br />           }<br />      });<br />

<?php echo $_POST["location"]; ?>

<?php<br />if($_SERVER['REQUEST_METHOD'] == "POST") {<br />  print_r($_POST);<br />  exit();<br />}<br />?><br /><script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.6.3/jquery.min.js"></script><br /><script><br />$(function() {<br /> $.ajax({<br />       type: "POST",<br />//        url: "index.php",<br />        data: "location=img_png_src",<br />        success: function(msg){<br />         alert( "Data Saved: " + msg );<br />           }<br />      });<br />});<br /></script><br />