PHP中常见的缓存技术实例分析

//刷新缓存
function recache($cachestr = '') {
if (!$cachestr) {
 $cachelist = array('config','class','archive','newment','newpost','link','tag','statistic','blog');
} else {
 $cachelist = explode(',',$cachestr);
 foreach ($cachelist as $cache) {
  $cachename = $cache.'_recache';
  if (function_exists($cachename)) {
  $cachename();
  }
 }
}
}

//将字符串写进文件
function writeToFile($cachename,$content = '') {
$allowcache = $cachelist = array('config','class','archive','newment','newpost','link','tag','statistic','blog');
if (in_array($cachename,$allowcache)) {
 $cache_dir = JBLOG_ROOT.'cache_data/';
 $cache_file_name = $cache_dir.'cache_'.$cachename.'.php';
 if (!is_dir($cache_dir)) {
  @mkdir($cache_dir,0777);
 }
 if ($fp = @fopen($cache_file_name,'wb')) {
  $content = "<?php\r\n//该文件是系统自动生成的缓存文件，请勿修改\r\n//创建时间".date('Y-m-d H:i:s',time())."\r\n\r\nif (!defined('IN_JBLOG')) {exit('Aess Denied!');}\r\n\r\n".$content."\r\n\r\n?>";
  @fwrite($fp,$content);
  @fclose();
  @chmod($cache_file_name,0777);
 } else {
  echo '缓存文件<b>'.$cache_dir.$cache_file_name.'</b>创建失败！<br />';
 }
} else {
 die('缓存名称<b>'.$cachename.'</b>不在系统允许的范围内！');
}
}

//缓存博客分类
function class_recache() {
global $db,$tablepre;
$content = '';
$sql = "SELECT id,classname,description,orderid,arum FROM `{$tablepre}class` ORDER BY orderid";
$result = $db->query($sql);
while ($row = $db->fetch_array($result)) {
 $content .= "\tarray(\r\n";
 $content .= "\t'id'=>'".addslashes($row['id'])."',\r\n";
 $content .= "\t'classname'=>'".addslashes($row['classname'])."',\r\n";
 $content .= "\t'description'=>'".addslashes($row['description'])."',\r\n";
 $content .= "\t'orderid'=>'".addslashes($row['orderid'])."',\r\n";
 $content .= "\t'arum'=>'".addslashes($row['arum'])."',\r\n";
 $content .= "\t),\r\n";
}
$content = substr($content,0,strrpos($content,','));
$content = "\$class_cache = array(\r\n{$content}\r\n);";
writeToFile('class',$content);
}

//加载系统设置信息，文件不存在则重建缓存
if ([email=!@include(JBLOG_ROOT.]!@include(JBLOG_ROOT.'cache_data/cache_config.php'[/email])) {
require_once(JBLOG_ROOT.'include/cache.func.php');
recache('config');
exit('成功创建系统配置信息缓存，请刷新页面！');
}
//加载缓存，缓存文件不存在则重建缓存
$cachestr = '';
$cachelist = array('class','archive','newment','newpost','link','tag','statistic','blog');
foreach ($cachelist as $cachename) {
$cachestr .= (@include(JBLOG_ROOT.'cache_data/cache_'.$cachename.'.php')) ? '' : $cachename.',';
}
$cachestr = substr($cachestr,0,strrpos($cachestr,','));
if ($cachestr) {
require_once(JBLOG_ROOT.'include/cache.func.php');
recache($cachestr);
exit('所有缓存重建完成，请刷新页面！');
}
unset($cachelist,$cachename,$cachestr);