<?php
$filename = "./jingtai.html";//定义一个变量来存放一个缓存文件的路径（相对于当前页面的路径）
//定义缓存有效期
$cachetime = 10;
//判断缓存文件是否存在
var_dump(filemtime($filename));
//filemtime($filename)不变,time()一直变，filemtime($filename)+10肯定会有小于time()的时候。
if(!file_exists($filename)||filemtime($filename)+$cachetime<time()){//filemtime($filename)获取文件修改时间，加上定义的缓存时间小于当前时间
//开启内存缓存 //filemtime()该文件上次修改内容
//filemtime($filename)第一次出现等于当前时间time();每过10秒走一次函数，filemtime($filename)的值就会改变
var_dump(time());
ob_start();
?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>无标题文档</title>
</head>
<body>
<table width="100%" border="1" cellpadding="0" cellspacing="0" >
<tr>
<td>学号</td>
<td>姓名</td>
<td>性别</td>
<td>生日</td>
<td>班级</td>
</tr>
<?php
//造连接对象
$db = new MySQLi("localhost","root","","ceshi");
//写SQL语句
$sql = "select * from student";
//执行
$result = $db->query($sql);
while($attr = $result->fetch_row()){
echo "<tr>
<td>{$attr[0]}</td>
<td>{$attr[1]}</td>
<td>{$attr[2]}</td>
<td>{$attr[3]}</td>
<td>{$attr[4]}</td>
</tr>";
}
?>
</table>
</body>
</html>
<?php
//从内存缓存中获取页面代码
$content = ob_get_contents();
//将获取到的内容存放到缓存文件
file_put_contents($filename,$content);
//清掉内存缓存
ob_flush();
echo "#####"; //测试是否调用了缓存文件，缓存文件不输出这句话
}
else{
//var_dump(filemtime($filename)); var_dump(time());
include($filename); //如果存在，调用缓存文件
}
?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>无标题文档</title>
</head>
<body>
<table width="100%" border="1" cellpadding="0" cellspacing="0" >
<tr>
<td>学号</td>
<td>姓名</td>
<td>性别</td>
<td>生日</td>
<td>班级</td>
</tr>
<tr>
<td>1</td>
<td>101</td>
<td>王超</td>
<td>男</td>
<td>2000-02-12 00:00:00</td>
</tr><tr>
<td>2</td>
<td>103</td>
<td>陆君</td>
<td>男</td>
<td>1974-06-03 00:00:00</td>
</tr><tr>
<td>3</td>
<td>105</td>
<td>匡明</td>
<td>男</td>
<td>1975-10-02 00:00:00</td>
</tr><tr>
<td>4</td>
<td>107</td>
<td>王丽</td>
<td>女</td>
<td>1976-01-23 00:00:00</td>
</tr><tr>
<td>5</td>
<td>108</td>
<td>曾华</td>
<td>男</td>
<td>1977-09-01 00:00:00</td>
</tr><tr>
<td>6</td>
<td>109</td>
<td>王芳</td>
<td>女</td>
<td>1975-02-10 00:00:00</td>
</tr><tr>
<td>7</td>
<td>110</td>
<td>刘备</td>
<td>男</td>
<td>0000-00-00 00:00:00</td>
</tr><tr>
<td>8</td>
<td>111</td>
<td>孙权1</td>
<td>男</td>
<td>0000-00-00 00:00:00</td>
</tr><tr>
<td>9</td>
<td>112</td>
<td>曹操</td>
<td>男</td>
<td>0000-00-00 00:00:00</td>
</tr><tr>
<td>10</td>
<td>113</td>
<td>刘邦</td>
<td>男</td>
<td>0000-00-00 00:00:00</td>
</tr><tr>
<td>11</td>
<td>114</td>
<td>周瑜</td>
<td>男</td>
<td>0000-00-00 00:00:00</td>
</tr><tr>
<td>17</td>
<td>098</td>
<td>zhangsan32</td>
<td>男</td>
<td>0000-00-00 00:00:00</td>
</tr> </table>
</body>
</html>