Comet 基于AJAX的HTTP长连接

<mce:script src="jquery.js" mce_src="jquery.js"></mce:script><mce:script type="text/javascript"><!-- window.onload = function() { getMsg(0); } function getMsg(time) { $.post("back.php", {'timestamp': time ,"num":Math.random()}, function(data) { var json = eval('('+ data +')'); document.getElementById("txt").innerHTML += json.msg+'<br>'; getMsg(json.timestamp); }); } function send() { var v = document.getElementById('msg').value; $('#msg').val(''); $.post("back.php", {'msg': v ,"num":Math.random()}, function(data) { }); }// --></mce:script><div id="txt" ></div><input type="text" id="msg"><input type="button" value="Send" onclick="send()"> 

<?phpset_time_limit(0);ob_end_clean();$file = dirname(__FILE__). '/data.txt';if(!empty($_REQUEST['msg'])){ file_put_contents($file, $_REQUEST['msg']); die('Write');}$lastmodif = isset($_REQUEST['timestamp']) ? intval($_REQUEST['timestamp']) : 0;$currentmodif = filemtime($file);while($currentmodif <= $lastmodif ){ sleep(2); clearstatcache(); $currentmodif = filemtime($file);}$response = array();$response['msg'] = file_get_contents($file);$response['timestamp'] = $currentmodif;$response['lasttime'] = $lastmodif;echo json_encode($response);flush();?>