请有人亲切地说明我创建并输出到 jsondata.php 的以下结果如何可以放入JavaScript中的变量中，以便我可以索引通过结果并在我的网站中使用Div。
需要的变量是：
$ lastplayed中的所有内容和$ secsemain的结果
我尝试使用下面的代码访问Javascript中的数据，...我知道它很糟糕!!
TEST1
<script>
url = jsondata.php;
var arr;
arr = <?php echo json_decode($lastplayed,TRUE); ?>;
</script>
以下是生成JSON数据的文件
FILE1（dblastplayedarray.php）
<?php
date_default_timezone_set('Europe/London');
require_once("DbConnect.php");
$sql = "SELECT `artist`, `title`, `label`, `albumyear`, `date_played`, `duration`,
`picture` FROM historylist ORDER BY `date_played` DESC LIMIT 5 ";
$result = $db->query($sql);
$lastplayed = array();
$i = 1;
while ($row=$result->fetch_object()) {
$lastplayed[$i]['artist'] = $row->artist;
$lastplayed[$i]['title'] = $row->title;
$lastplayed[$i]['label'] = $row->label;
$lastplayed[$i]['albumyear'] = $row->albumyear;
$lastplayed[$i]['date_played'] = $row->date_played;
$lastplayed[$i]['duration'] = $row->duration;
$lastplayed[$i]['picture'] = $row->picture;
$i++;
}
$starttime = strtotime($lastplayed[1]['date_played']);
$curtime = time();
$timeleft = $starttime+round($lastplayed[1]['duration']/1000)-$curtime;
$secsremain = (round($lastplayed[1]['duration'] / 1000)-($curtime-$starttime))
?>
文件2（jsondata.php）
<?php
require_once("dblastplayedarray.php");
echo json_encode($lastplayed);
?>
答案 0 :(得分：1)
首先，您不希望生成对PHP脚本的连续请求，只是为了获得当前歌曲的剩余时间。最好让JavaScript处理它。
您的JavaScript必须决定两件事：
可能的解决方案是：
让你的JS代码计算当前歌曲结束的时间。 当此时间达到零时，通过PHP查询您的数据库以获取下一批歌曲 收到更新后，再次计算当前歌曲结束的时间并等待它达到零（使用计时器）。
要从PHP获得结果，最好使用Ajax来避免完全刷新页面。
把所有这些放在一起，你应该有类似的东西：
var PlayList = function (onUpdate, onError)
{
// store user callbacks
this.onUpdate = onUpdate;
this.onError = onError;
// setup internal event handlers
this.onSongEnd = onSongEnd.bind (this);
// allocate an Ajax handler
try
{
this.ajax = window.XMLHttpRequest
? new XMLHttpRequest()
: new ActiveXObject("Microsoft.XMLHTTP");
}
catch (e)
{
// fatal error: could not get an Ajax handler
this.onError ("could not allocated Ajax handler");
}
this.ajax.onreadystatechange = onAjaxUpdate.bind(this);
// launch initial request
this.onSongEnd ();
// ------------------------------------------
// interface
// ------------------------------------------
// try another refresh in the specified amount of seconds
this.retry = function (delay)
{
setTimeout (this.onSongEnd, delay*1000);
}
// ------------------------------------------
// ancillary functions
// ------------------------------------------
// called when it's time to refresh the playlist
function onSongEnd ()
{
// ask for a playlist update
this.ajax.open('GET', 'playlist.php', // <-- reference your PHP script here
true);
this.ajax.send(null);
}
// called to handle Ajax request progress
function onAjaxUpdate ()
{
if (this.ajax.readyState != 4) return;
if (this.ajax.status == 200)
{
// get our response
var list = eval ('('+this.ajax.responseText+')');
// compute milliseconds remaining till the end of the current song
var start = new Date (list[0].date_played).getTime();
var now = new Date ( ).getTime();
var d = start - now
+ parseInt(list[0].duration); // JSON data are plain strings, don't forget
// to convert then to numbers if need be
if (d < 0)
{
// no new song started, retry in 10 seconds
d = 10000;
}
else
{
// notify caller
this.onUpdate (list);
}
// schedule next refresh
setTimeout (this.onSongEnd, d);
}
else
{
// Ajax request failed. Most likely a fatal error
this.onError ("Bloody Ajax request failed");
}
}
}
请注意，这是纯粹的，纯粹的JavaScript。这是教育代码，因此如果您有兴趣，可以使用它来查看使用匿名Ajax的示例。
由于bind()的使用，它在IE8中不起作用，但如果您计划支持旧牛，则可以轻松添加包装函数。
使用JQuery goo可以更容易地进行Ajax查询。我自己永远无法忍受这些东西，但毫无疑问，你会发现很多人都愿意向你展示它是如何完成的。
var list = new PlayList (playlistupdate, playlisterror);
function playlistupdate (list)
{
// do whatever you want with the playlist
console.log ("Playlist update at "+new Date().toTimeString());
for (var i = 0 ; i != list.length ; i++)
{
var song = list[i];
console.log (i+" "+song.title);
}
}
function playlisterror (msg)
{
// display error message
console.log ("Ajax error: "+msg);
// may want to retry, but chances of success are slim
list.retry (10); // retry in 10 seconds
}
// make this query non cacheable
/*
* if you don't do this, your browser will cache
* your first query and ignore the subsequent ones
*/
header("Cache-Control: no-cache");
// open your DB connection
require_once("DbConnect.php");
// fetch playlist
$result = $db->query(
"SELECT `artist`, `title`, `label`, `albumyear`, `date_played`, `duration`, `picture` "
."FROM historylist ORDER BY `date_played` DESC LIMIT 5 ");
// this little line replaces your bunch of code
while ($row=$result->fetch_object()) $list[] = $row;
// encode and send the result
echo json_encode ($list);
请注意no-cache标头。这是阻止浏览器缓存请求的最简洁方法。
前面提到的JQuery goo将为您提供一个糟糕的解决方案，包括在查询后添加一些垃圾（即用playlist.php替换playlist.php?some_random_junk以强制浏览器将每个请求作为唯一处理，从而污染您的浏览器缓存没有充分理由）。
由于您可以控制执行查询的PHP，因此可以更好地处理源代码中的问题。
我写了一个快速＆amp;肮脏的测试工具免除数据库
// read our dummy DB
if (file_exists ("playlist.txt"))
{
foreach (explode ("\n", file_get_contents ("playlist.txt")) as $i => $line)
{
$line = explode ('|', $line);
foreach (array ('title', 'date_played', 'duration') as $k =>$f)
{
$db[$i]->$f = $line[$k];
}
}
$last_ended = strtotime($db[count($db)-1]->date_played)
+ $db[count($db)-1]->duration/1000;
}
else $last_ended = time();
function song_name ()
{
return
array_rand (array_flip(array("A", "Your", "Some", "This", "No"))). " ".
array_rand (array_flip(array("beautiful", "weird", "delightful", "doomed", "pink"))). " ".
array_rand (array_flip(array("love", "kiss", "baby", "monster", "dude", "car")));
}
// add a new dummy song to our DB if the last one has ended
if ($last_ended <= time())
{
$changed = true;
$db[] = array ("title" => song_name(), "date_played" => date("M d Y H:i:s", $last_ended), "duration" => rand(10,20)*1000);
// store only the last 5 songs in the dummy DB
$db = array_slice ($db, -5);
foreach ($db as $k => $record)
{
$out[$k] = implode ('|', (array)$record);
}
file_put_contents ("playlist.txt", implode ("\n", $out));
}
// make this query non cacheable
header("Cache-Control: no-cache");
// get DB output
$list = array_slice (array_reverse ($db), 0, 5);
// encode and send it
echo json_encode ($list);
Playlist update at 00:34:26 GMT+0100 (Paris, Madrid)
0 Your doomed love
1 Your doomed dude
2 No beautiful kiss
3 Some pink baby
4 Your delightful car
Playlist update at 00:34:38 GMT+0100 (Paris, Madrid)
0 No doomed baby
1 Your doomed love
2 Your doomed dude
3 No beautiful kiss
4 Some pink baby
您可以同时获取两个测试文件here 由于难以以可读的方式模拟Ajax请求，我没有做JSFiddle。
根据流行的请求，这里有一个示例代码，它在网页上显示某些内容，而不是简单地将列表抄送到控制台。
您只需要更改playlistupdate这样的内容：
function playlistupdate (list)
{
// display the playlist inside a table
// table header
var table = '<tr>';
for (var j in list[0]) table += '<th>'+j+'</th>';
table += '</tr>';
// list items
for (var i = 0 ; i != list.length ; i++)
{
table += '<tr>';
for (var j in list[i])
{
table += '<td>'+list[i][j]+'</td>';
}
table += '</tr>';
}
// update table
document.getElementById ('playlist').innerHTML = table;
}
您需要在HTML中的某个位置定义一个空表：
<table id='playlist'></table>
答案 1 :(得分：0)
将LIMIT 5更改为LIMIT 1或删除此。我认为您的代码具有多个数组并且这在此源中不可用!!!只是我想。我不是试试......
TEST1是php文件？
将var arr更改为var arr = new Array();
通过Ajax发送信息并使用它......