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How to implement caching function in PHP
First use the function "json_eecode()" to JSON encode the data to be cached; then use the cached data Create a file with the file name as the key name; finally write the JSON-encoded data to the file through the "file_put_contents()" function.
Sample code:
<?php
class FileCache
{
/**
* 缓存目录
* @var
*/
private $cache_dir;
/**
* @param $cache_dir
* @throws Exception
*/
public function __construct($cache_dir)
{
$this->cache_dir = $cache_dir;
if (!is_dir($cache_dir)) {
$make_dir_result = mkdir($cache_dir, 0755, true);
if ($make_dir_result === false) throw new Exception('Cannot create the cache directory');
}
}
/**
* 根据key获取值，会判断是否过期
* @param $key
* @return mixed
*/
public function get($key)
{
$cache_data = $this->getItem($key);
if ($cache_data === false || !is_array($cache_data)) return false;
return $cache_data['data'];
}
/**
* 添加或覆盖一个key
* @param $key
* @param $value
* @param $expire
* @return mixed
*/
public function set($key, $value, $expire = 0)
{
return $this->setItem($key, $value, time(), $expire);
}
/**
* 设置包含元数据的信息
* @param $key
* @param $value
* @param $time
* @param $expire
* @return bool
*/
private function setItem($key, $value, $time, $expire)
{
$cache_file = $this->createCacheFile($key);
if ($cache_file === false) return false;
$cache_data = array('data' => $value, 'time' => $time, 'expire' => $expire);
$cache_data = json_encode($cache_data);
$put_result = file_put_contents($cache_file, $cache_data);
if ($put_result === false) return false;
return true;
}
/**
* 创建缓存文件
* @param $key
* @return bool|string
*/
private function createCacheFile($key)
{
$cache_file = $this->path($key);
if (!file_exists($cache_file)) {
$directory = dirname($cache_file);
if (!is_dir($directory)) {
$make_dir_result = mkdir($directory, 0755, true);
if ($make_dir_result === false) return false;
}
$create_result = touch($cache_file);
if ($create_result === false) return false;
}
return $cache_file;
}
/**
* 判断Key是否存在
* @param $key
* @return mixed
*/
public function has($key)
{
$value = $this->get($key);
if ($value === false) return false;
return true;
}
/**
* 加法递增
* @param $key
* @param int $value
* @return mixed
*/
public function increment($key, $value = 1)
{
$item = $this->getItem($key);
if ($item === false) {
$set_result = $this->set($key, $value);
if ($set_result === false) return false;
return $value;
}
$check_expire = $this->checkExpire($item);
if ($check_expire === false) return false;
$item['data'] += $value;
$result = $this->setItem($key, $item['data'], $item['time'], $item['expire']);
if ($result === false) return false;
return $item['data'];
}
/**
* 减法递增
* @param $key
* @param int $value
* @return mixed
*/
public function decrement($key, $value = 1)
{
$item = $this->getItem($key);
if ($item === false) {
$value = 0 - $value;
$set_result = $this->set($key, $value);
if ($set_result === false) return false;
return $value;
}
$check_expire = $this->checkExpire($item);
if ($check_expire === false) return false;
$item['data'] -= $value;
$result = $this->setItem($key, $item['data'], $item['time'], $item['expire']);
if ($result === false) return false;
return $item['data'];
}
/**
* 删除一个key，同事会删除缓存文件
* @param $key
* @return mixed
*/
public function delete($key)
{
$cache_file = $this->path($key);
if (file_exists($cache_file)) {
$unlink_result = unlink($cache_file);
if ($unlink_result === false) return false;
}
return true;
}
/**
* 清楚所有缓存
* @return mixed
*/
public function flush()
{
return $this->delTree($this->cache_dir);
}
/**
* 递归删除目录
* @param $dir
* @return bool
*/
function delTree($dir)
{
$files = array_diff(scandir($dir), array('.', '..'));
foreach ($files as $file) {
(is_dir("$dir/$file")) ? $this->delTree("$dir/$file") : unlink("$dir/$file");
}
return rmdir($dir);
}
/**
* 根据key获取缓存文件路径
*
* @param string $key
* @return string
*/
protected function path($key)
{
$parts = array_slice(str_split($hash = md5($key), 2), 0, 2);
return $this->cache_dir . '/' . implode('/', $parts) . '/' . $hash;
}
/**
* 获取含有元数据的信息
* @param $key
* @return bool|mixed|string
*/
protected function getItem($key)
{
$cache_file = $this->path($key);
if (!file_exists($cache_file) || !is_readable($cache_file)) {
return false;
}
$cache_data = file_get_contents($cache_file);
if (empty($cache_data)) return false;
$cache_data = json_decode($cache_data, true);
if ($cache_data) {
$check_expire = $this->checkExpire($cache_data);
if ($check_expire === false) {
$this->delete($key);
return false;
}
}
return $cache_data;
}
/**
* 检查key是否过期
* @param $cache_data
* @return bool
*/
protected function checkExpire($cache_data)
{
$time = time();
$is_expire = intval($cache_data['expire']) !== 0 && (intval($cache_data['time']) + intval($cache_data['expire']) < $time);
if ($is_expire) return false;
return true;
}
}Recommended tutorial: "PHP Tutorial"
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