如何用php+ajax实现页面的局部刷新？（转）

client.html

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html>
 <head>
  <meta http-equiv="content-type" content="text/html; charset=utf-8">
  <title> jquery demo </title>
  <script src="//code.jquery.com/jquery-1.11.0.min.js"></script>
  <script type="text/javascript">
    function show(){
        $.get( "server.php", function(data) {
            $('#txt').html(data.content);
        }, "json" );
    }
  </script>
 
 </head>
 
 <body>
    <p>這裡不會被刷新</p>
    <div id="txt">原來內容</div>
    <input type="button" value="刷新內容" onclick="show()">
 </body>
</html>

server.php

<?php
$ret = array();
$ret['content'] = '新內容';
 
echo json_encode($ret);
 
?>