<!--demo.html中内容-->
<body>
<img id="time" src="test.php" />
<script>
setInterval(function(){
//让时间动起来
document.getElementById("time").src="test.php?"+Math.random();
},1000);
</script>
</body>
<!--test.php中内容-->
<?php
//获取系统时间,设置时区
date_default_timezone_set("PRC");
$h = date("H");
$i = date("i");
$s = date("s");
//1 创建资源（画布的大小）
$img = imagecreatetruecolor(200, 250);
//设置画布的颜色
$white = imagecolorallocate($img, 0xFF, 0xFF, 0xFF);
$red = imagecolorallocate($img, 255, 0, 0);
$blue = imagecolorallocate($img, 0, 0, 0XFF);
$pink = imagecolorallocate($img, 0XFF, 0, 0XFF);
$green = imagecolorallocate($img, 0, 0xFF, 0);
imagefill($img, 0, 0, $white);
//2. 制作各种颜色
//画空心圆
imageellipse($img, 100, 100, 190, 190, $blue);
//画实心圆
imagefilledellipse($img, 100, 100, 4, 4, $blue);
imagestring($img, 3, 95, 8, "12", $blue);
imagestring($img, 3,180, 95, "03", $blue);
imagestring($img, 3, 95, 180, "06", $blue);
imagestring($img, 3, 11, 95, "09", $blue);
//秒针
$len = 80;
$a = $len*sin(pi()/30*$s);
$b = $len*cos(pi()/30*$s);
$x = 100 + $a;
$y = 100 - $b;
imageline($img, 100, 100, $x, $y, $red);
//数字的时间
imagestring($img, 5, 20, 230, "NOW: {$h}:{$i}:{$s}", $red);
//4保存，或输出给浏览, 写第二个参数就是保存
header("Content-Type:images/gif");
imagegif($img);
//5. 释放资源
imagedestroy($img);