php 清除换行符,清除制表符,去掉注释标记总结

<?php
 /**
  * 压缩html : 清除换行符,清除制表符,去掉注释标记  
  * @param   $string  
  * @return  压缩后的$string 
  * */
 function compress_html($string) {  
     $string = str_replace("rn", '', $string); //清除换行符  
     $string = str_replace("n", '', $string); //清除换行符  
     $string = str_replace("t", '', $string); //清除制表符  
     $pattern = array (  
                     "/> *([^ ]*) *</", //去掉注释标记  
                     "/[s]+/",  
                     "/<!--[^!]*-->/",  
                     "/" /",  
                     "/ "/",  
                     "'/*[^*]**/'" 
                     );  
     $replace = array (  
                     ">\1<",  
                     " ",  
                     "",  
                     """,  
                     """,  
                     "" 
                     );  
     return preg_replace($pattern, $replace, $string);  
 }

<?php
$str="i   am    a     booknnnnnmoth";
//去除所有的空格和换行符
echo preg_replace("/[s]{2,}/","",$str).'<br>';
//去除多余的空格和换行符，只保留一个
echo preg_replace("/([s]{2,})/","\1",$str);
?>

<?php
// $document 应包含一个 HTML 文档。
// 本例将去掉 HTML 标记，javascript 代码
// 和空白字符。还会将一些通用的
// HTML 实体转换成相应的文本。

$search = array ("'<script[^>]*?>.*?</script>'si",  // 去掉 javascript
                 "'<[/!]*?[^<>]*?>'si",           // 去掉 HTML 标记
                 "'([rn])[s]+'",                 // 去掉空白字符
                 "'&(quot|#34);'i",                 // 替换 HTML 实体
                 "'&(amp|#38);'i",
                 "'&(lt|#60);'i",
                 "'&(gt|#62);'i",
                 "'&(nbsp|#160);'i",
                 "'&(iexcl|#161);'i",
                 "'&(cent|#162);'i",
                 "'&(pound|#163);'i",
                 "'&(copy|#169);'i",
                 "'&#(d+);'e");                    // 作为 PHP 代码运行

$replace = array ("",
                  "",
                  "\1",
                  """,
                  "&",
                  "<",
                  ">",
                  " ",
                  chr(161),
                  chr(162),
                  chr(163),
                  chr(169),
                  "chr(\1)");

$text = preg_replace ($search, $replace, $document);
?>

server
  {
    listen       80;
    server_name  www.yourdomain.com 192.168.8.42;
    index index.html index.htm;
    root  /data0/htdocs/www; 

    location /
    {
         #如果后端的服务器返回502、504、执行超时等错误，自动将请求转发到upstream负载均衡池中的另一台服务器，实现故障转移。
         proxy_next_upstream http_502 http_504 error timeout invalid_header;
         proxy_cache cache_one;
         #对不同的HTTP状态码设置不同的缓存时间
         proxy_cache_valid  200 304 12h;
         #以域名、URI、参数组合成Web缓存的Key值，Nginx根据Key值哈希，存储缓存内容到二级缓存目录内
         proxy_cache_key $host$uri$is_args$args;
         proxy_set_header Host  $host;
         proxy_set_header X-Forwarded-For  $remote_addr;
         proxy_pass http://backend_server;
         expires      1d;
    }
   
    #用于清除缓存，假设一个URL为http://192.168.8.42/test.txt，通过访问http://192.168.8.42/purge/test.txt就可以清除该URL的缓存。
    location ~ /purge(/.*)
    {
     #设置只允许指定的IP或IP段才可以清除URL缓存。
     allow            127.0.0.1;
     allow            192.168.0.0/16;
     deny            all;
     proxy_cache_purge    cache_one   $host$1$is_args$args;
    }   

    #扩展名以.php、.jsp、.cgi结尾的动态应用程序不缓存。
    location ~ .*.(php|jsp|cgi)?$
    {
         proxy_set_header Host  $host;
         proxy_set_header X-Forwarded-For  $remote_addr;
         proxy_pass http://backend_server;
    }

    access_log  off;
  }
}
 

<?php

class Cache
{

    private static $_instance;
    protected $_cacheId = null;

    const CLEANING_MODE_ALL  = 'all';
    const CLEANING_MODE_OLD = 'old';

    protected $_options = array(
        'cache_dir' => null,                  //数据缓存目录
        'life_time' => 7200,                  //缓存时间
        'page_dir' => null,                   //文本缓存目录
        'cache_prefix' => 'cache_'        //缓存前缀
    );

    private function __construct(){}
  
    //创建__clone方法防止对象被复制克隆
    private function __clone(){}
  
    /**
     * 取缓存对象，如果存在直接返回，如果不存在实例化本身
     * @return object cache
     */
    public static function getInstance(){
      
        if(! self::$_instance){
      
            self::$_instance = new self();
        }
      
        return self::$_instance;
    }
      
    /**
     * 设置缓存参数集
     * @param array $options 要设置的缓存参数集
     */
    public function setOptions($options = array()){
  
        while (list($name, $value) = each($options)) {
            $this->setOption($name, $value);
        }
    }
  
    /**
     * 取得当前缓存参数，如果$name为空返回全部参数，否则返回该参数值
     * @param string $name 要返回的参数名称
     * @return string or array $option;
     */
    public function getOption($name = null){
  
        if(null === $name)
            return $this->_options;
  
        if (!is_string($name)) {
            throwException("不正确的参数名称 : $name");
        }
      
        if (array_key_exists($name, $this->_options)){
            return $this->_options[$name];
        }
    }
  
    /**
     * 设置缓存参数
     * @param array $options 要设置的缓存参数
     */
    protected function setOption($name, $value){
  
        if (!is_string($name)) {
            throwException("不正确的参数名称 : $name");
        }
        $name = strtolower($name);
        if (array_key_exists($name, $this->getOption())){
            $this->_options[$name] = $value;
        }
      
        if ($this->_options['cache_dir'] === null) {
            $this->setOption('cache_dir', $this->getTmpDir() . DIRECTORY_SEPARATOR);
        }
      
        if ($this->_options['page_dir'] === null) {
            $this->setOption('page_dir', $this->getTmpDir() . DIRECTORY_SEPARATOR);
        }
    }
  
    /**
     * 读取数据缓存，如果不存在或过期，返回false
     * @param string $id 缓存ID
     * @return false or data
     */
    public function load($id){

        $this->_cacheId = $id;      
        $file = $this->getOption('cache_dir') . $this->getOption('cache_prefix') . $this->_cacheId;
              
        if (@filemtime($file) >= time()){
      
            return unserialize(file_get_contents($file));
        } else {
            @unlink($file);
            return false;
        }
    }
  
    /**
     * 保存数据缓存，并设置缓存过期时间
     * @param array or string $data 要缓存的数据
     * @param int $lifeTime 缓存过期时间
     */
    public function save($data, $lifeTime = null){
  
        if(null !== $lifeTime)
            $this->setOption('life_time', $lifeTime);
  
        $file = $this->getOption('cache_dir') . $this->getOption('cache_prefix') . $this->_cacheId;
        $data = serialize($data);
        @file_put_contents($file, $data);
        @chmod($file, 0777);
        @touch($file, time() + $this->getOption('life_time']));
    }  
  
    /**
     * 读取输出缓存，如果不存在或缓存过期将重新开启输出缓存
     * @param string $id 缓存ID
     */
    public function start($id){

        $this->_cacheId = $id;
        $file = $this->getOption('page_dir') . $this->getOption('cache_prefix') . $this->_cacheId;
              
        if (@filemtime($file) >= time()){
      
            return file_get_contents($file);
        } else {
            @unlink($file);
            ob_start();
            return false;
        }
    }

    /**
     * 删除指定ID缓存
     * @param string $id 缓存ID
     */
    public function remove($id){

        $this->_cacheId = $id;
        //删除附合条件的数据缓存
        $file = $this->getOption('cache_dir') . $this->getOption('cache_prefix') . $this->_cacheId;
        @unlink($file);
        //删除附合条件的输出缓存
        $file = $this->getOption('page_dir') . $this->getOption('cache_prefix') . $this->_cacheId;
        @unlink($file);
    }
  
    /**
     * 保存输出缓存，并设置缓存过期时间
     * @param int $lifeTime 缓存过期时间
     */
    public function end($lifeTime = null){

        if(null !== $lifeTime)
            $this->setOption('life_time', $lifeTime);
  
        $file = $this->getOption('page_dir') . $this->getOption('cache_prefix') . $this->_cacheId;
        $data = ob_get_contents();
        ob_end_clean();
        @file_put_contents($file, $data);
        @chmod($file, 0777);
        @touch($file, time() + $this->getOption('life_time']));
    }
  
    /**
     * 根据参数清除相应缓存
     * @param string $mode 缓存类型，包括(CLEANING_MODE_ALL:所有缓存, CLEANING_MODE_OLD: 过期缓存)
     */
    public function clear($mode = CLEANING_MODE_OLD){
  
        $dirs = array('cache_dir', 'page_dir');
        foreach($dirs as $value){
            if(null != $this->getOption($value)){
                $files = scandir($this->getOption($value));
                switch ($mode) {

                    case CLEANING_MODE_ALL:
                    default:
                        foreach ($files as $val){
                            @unlink($this->getOption($value) . $val);
                        }
                        break;

                    case CLEANING_MODE_OLD:
                    default:
                        foreach ($files as $val){
                            if (filemtime($this->getOption($value) . $val) < time()){
                                @unlink($this->getOption($value) . $val);
                            }
                        }
                        break;
                }
            }
        }
    }
  
    /**
     * 取临时文件夹为缓存文件夹
     * @return $dir 临时文件夹路径
     */
    public function getTmpDir(){
  
        $tmpdir = array();
        foreach (array($_ENV, $_SERVER) as $tab) {
            foreach (array('TMPDIR', 'TEMP', 'TMP', 'windir', 'SystemRoot') as $key) {
                if (isset($tab[$key])) {
                    if (($key == 'windir') or ($key == 'SystemRoot')) {
                        $dir = realpath($tab[$key] . '\temp');
                    } else {
                        $dir = realpath($tab[$key]);
                    }
                    if ($this->_isGoodTmpDir($dir)) {
                        return $dir;
                    }
                }
            }
        }
        $upload = ini_get('upload_tmp_dir');
        if ($upload) {
            $dir = realpath($upload);
            if ($this->_isGoodTmpDir($dir)) {
                return $dir;
            }
        }
        if (function_exists('sys_get_temp_dir')) {
            $dir = sys_get_temp_dir();
            if ($this->_isGoodTmpDir($dir)) {
                return $dir;
            }
        }
        //通过尝试创建一个临时文件来检测
        $tempFile = tempnam(md5(uniqid(rand(), TRUE)), '');
        if ($tempFile) {
            $dir = realpath(dirname($tempFile));
            unlink($tempFile);
            if ($this->_isGoodTmpDir($dir)) {
                return $dir;
            }
        }
        if ($this->_isGoodTmpDir('/tmp')) {
            return '/tmp';
        }
        if ($this->_isGoodTmpDir('\temp')) {
            return '\temp';
        }
        throw new Exception('无法确定临时目录，请手动指定cache_dir', E_USER_ERROR);
    }

    /**
     * 验证给定的临时目录是可读和可写的
     *
     * @param string $dir 临时文件夹路径
     * @return boolean true or false 临时文件夹路径是否可读写
     */
    protected function _isGoodTmpDir($dir){
  
        if (is_readable($dir)) {
            if (is_writable($dir)) {
                return true;
            }
        }
        return false;
    }

}//endclass

SELECT * FROM article
WHERE article_category IN (2,3)
ORDER BY article_id DESC
LIMIT 5

(
    SELECT * FROM article
    WHERE article_category=2
    ORDER BY article_id DESC
    LIMIT 5
) UNION ALL (
    SELECT * FROM article
    WHERE article_category=3
    ORDER BY article_id DESC
    LIMIT 5
)
ORDER BY article_id DESC
LIMIT 5
// 执行时间：0.0261

GET /Path/FileName HTTP/1.0
Host: www.server.com:80

$speed = 512;//此参数为下载最大速度
$pos = strrpos($file_path, "/");
$file_name = substr($file_path, $pos+1);
$file_size = filesize($file_path);
$ranges = getRange($file_size);
$fh =  fopen($file_path, "rb");
header('Cache-control: public');
header('Content-Type: application/octet-stream');
header('Content-Disposition: attachment; filename='.$file_name);
if ($ranges != null) {
    header('HTTP/1.1 206 Partial Content');
    header('Accept-Ranges: bytes');
    header(sprintf('Content-Length: %u',$ranges['end'] - $ranges['start']));
    header(sprintf('Content-Range: bytes %s-%s/%s', $ranges['start'], $ranges['end'], $file_size));
    fseek($fh, sprintf('%u',$ranges['start']));
}else{
    header("HTTP/1.1 200 OK");
    header(sprintf('Content-Length: %s', $file_size));
}
while(!feof($fh))
{
    echo  fread($fh, round($speed*1024, 0));
    ob_flush();
    sleep(1);
}
($fh != null) && fclose($fh);