ajax保持连接,AJAX长轮询不会保持连接打开

我一直在试图在过去两天得到这个工作没有运气。它执行一次，但在初始加载后无法继续更新。该功能不会自动更新，也不会在30秒后重新启动。代码对我来说看起来很好，但显然我有一些关于长轮询的知识缺口，这导致了这种情况不起作用。如果有人有片刻，我会很感激，如果你能梳理这一点，告诉我什么是我做错了。任何帮助表示赞赏，谢谢。AJAX长轮询不会保持连接打开

的JavaScript/jQuery的

function poll(pid){

var dataString = 'pid=' + pid;

$.ajax({type: 'GET', url: 'http://localhost:8888/mysite/execs/vote_count.php', data: dataString, async: true, cache: false, success: function(data){

var post = $('#' +pid);

var post_children = post.children();

var upvotes = post_children.find('.upvotes');

var downvotes = post_children.find('.downvotes');

downvotes.text("-" + data.downvotes);

upvotes.text("+" + data.upvotes);

}, dataType: "json", complete: poll, timeout: 30000 });

};

$(".post").each(function(){

poll($(this).attr("id"));

});

PHP(vote_count.php)

$hostname = 'localhost';

$username = 'root';

$password = 'root';

$database = 'database';

try {

$dbh = new PDO("mysql:host=$hostname;dbname=$database", $username, $password);

$dbh->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

$stmt = $dbh->prepare("SELECT * FROM vote WHERE post = :pid AND rating = 'votedown'");

$pid = $_GET['pid'];

$stmt->bindParam(':pid', $pid, PDO::PARAM_STR);

$stmt->execute();

$result = $stmt->fetchAll();

}

catch(PDOException $e)

{

echo $e->getMessage();

}

$stmt->execute();

$downvotes = $stmt->rowCount();

try {

$dbh = new PDO("mysql:host=$hostname;dbname=$database", $username, $password);

$dbh->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

$stmt = $dbh->prepare("SELECT * FROM vote WHERE post = :pid AND rating = 'voteup'");

$pid = $_GET['pid'];

$stmt->bindParam(':pid', $pid, PDO::PARAM_STR);

$stmt->execute();

$result = $stmt->fetchAll();

}

catch(PDOException $e)

{

echo $e->getMessage();

}

$stmt->execute();

$upvotes = $stmt->rowCount();

$arr = array("downvotes"=>$downvotes,"upvotes"=>$upvotes);

echo json_encode($arr);

$dbh = null;

?>

2012-04-18

Ian