CodeIgniter 核心代码阅读-输出文件Output.php

Output.php--输出文件

<?php  if ( ! defined('BASEPATH')) exit('No direct script access allowed');//输出文件class CI_Output {//输出结果protected $final_output;//缓存时间protected $cache_expiration= 0;        //HTTP头protected $headers= array();//mime输出类型protected $mime_types= array();//分析器启用标记protected $enable_profiler= FALSE;        //压缩启用标记protected $_zlib_oc= FALSE;//分析器数组protected $_profiler_sections = array();//解析{elapsed_time}、{memory_usage}等内容的标记 protected $parse_exec_vars= TRUE;//构造函数function __construct(){$this->_zlib_oc = @ini_get('zlib.output_compression');// Get mime types for laterif (defined('ENVIRONMENT') AND file_exists(APPPATH.'config/'.ENVIRONMENT.'/mimes.php')){    include APPPATH.'config/'.ENVIRONMENT.'/mimes.php';}else{include APPPATH.'config/mimes.php';}$this->mime_types = $mimes;log_message('debug', "Output Class Initialized");}//获得输出字符串function get_output(){return $this->final_output;}//设置输出字符串function set_output($output){$this->final_output = $output;return $this;}//在输出字符串后追加字符串function append_output($output){if ($this->final_output == ''){$this->final_output = $output;}else{$this->final_output .= $output;}return $this;}//设置HTTP头function set_header($header, $replace = TRUE){// If zlib.output_compression is enabled it will compress the output,// but it will not modify the content-length header to compensate for// the reduction, causing the browser to hang waiting for more data.// We'll just skip content-length in those cases.if ($this->_zlib_oc && strncasecmp($header, 'content-length', 14) == 0){return;}$this->headers[] = array($header, $replace);return $this;}//设置HTTP文件内容类型function set_content_type($mime_type){if (strpos($mime_type, '/') === FALSE){$extension = ltrim($mime_type, '.');// Is this extension supported?if (isset($this->mime_types[$extension])){$mime_type =& $this->mime_types[$extension];if (is_array($mime_type)){$mime_type = current($mime_type);}}}$header = 'Content-Type: '.$mime_type;$this->headers[] = array($header, TRUE);return $this;}//设置HTTP状态function set_status_header($code = 200, $text = ''){set_status_header($code, $text);return $this;}//启用停用分析器function enable_profiler($val = TRUE){$this->enable_profiler = (is_bool($val)) ? $val : TRUE;return $this;}//设置分析器的每个部分function set_profiler_sections($sections){foreach ($sections as $section => $enable){$this->_profiler_sections[$section] = ($enable !== FALSE) ? TRUE : FALSE;}return $this;}//设置缓存时间function cache($time){$this->cache_expiration = ( ! is_numeric($time)) ? 0 : $time;return $this;}//向浏览器输出内容function _display($output = ''){// Note:  We use globals because we can't use $CI =& get_instance()// since this function is sometimes called by the caching mechanism,// which happens before the CI super object is available.global $BM, $CFG;// Grab the super object if we can.if (class_exists('CI_Controller')){$CI =& get_instance();}// --------------------------------------------------------------------// Set the output dataif ($output == ''){$output =& $this->final_output;}// --------------------------------------------------------------------// Do we need to write a cache file?  Only if the controller does not have its// own _output() method and we are not dealing with a cache file, which we// can determine by the existence of the $CI object aboveif ($this->cache_expiration > 0 && isset($CI) && ! method_exists($CI, '_output')){$this->_write_cache($output);}// --------------------------------------------------------------------// Parse out the elapsed time and memory usage,// then swap the pseudo-variables with the data$elapsed = $BM->elapsed_time('total_execution_time_start', 'total_execution_time_end');if ($this->parse_exec_vars === TRUE){$memory = ( ! function_exists('memory_get_usage')) ? '0' : round(memory_get_usage()/1024/1024, 2).'MB';$output = str_replace('{elapsed_time}', $elapsed, $output);$output = str_replace('{memory_usage}', $memory, $output);}// --------------------------------------------------------------------// Is compression requested?if ($CFG->item('compress_output') === TRUE && $this->_zlib_oc == FALSE){if (extension_loaded('zlib')){if (isset($_SERVER['HTTP_ACCEPT_ENCODING']) AND strpos($_SERVER['HTTP_ACCEPT_ENCODING'], 'gzip') !== FALSE){ob_start('ob_gzhandler');}}}// --------------------------------------------------------------------// Are there any server headers to send?if (count($this->headers) > 0){foreach ($this->headers as $header){@header($header[0], $header[1]);}}// --------------------------------------------------------------------// Does the $CI object exist?// If not we know we are dealing with a cache file so we'll// simply echo out the data and exit.if ( ! isset($CI)){echo $output;log_message('debug', "Final output sent to browser");log_message('debug', "Total execution time: ".$elapsed);return TRUE;}// --------------------------------------------------------------------// Do we need to generate profile data?// If so, load the Profile class and run it.if ($this->enable_profiler == TRUE){$CI->load->library('profiler');if ( ! empty($this->_profiler_sections)){$CI->profiler->set_sections($this->_profiler_sections);}// If the output data contains closing </body> and </html> tags// we will remove them and add them back after we insert the profile dataif (preg_match("|</body>.*?</html>|is", $output)){$output  = preg_replace("|</body>.*?</html>|is", '', $output);$output .= $CI->profiler->run();$output .= '</body></html>';}else{$output .= $CI->profiler->run();}}// --------------------------------------------------------------------// Does the controller contain a function named _output()?// If so send the output there.  Otherwise, echo it.if (method_exists($CI, '_output')){$CI->_output($output);}else{echo $output;  // Send it to the browser!}log_message('debug', "Final output sent to browser");log_message('debug', "Total execution time: ".$elapsed);}//写缓存文件function _write_cache($output){$CI =& get_instance();$path = $CI->config->item('cache_path');$cache_path = ($path == '') ? APPPATH.'cache/' : $path;if ( ! is_dir($cache_path) OR ! is_really_writable($cache_path)){log_message('error', "Unable to write cache file: ".$cache_path);return;}$uri =$CI->config->item('base_url').$CI->config->item('index_page').$CI->uri->uri_string();$cache_path .= md5($uri);if ( ! $fp = @fopen($cache_path, FOPEN_WRITE_CREATE_DESTRUCTIVE)){log_message('error', "Unable to write cache file: ".$cache_path);return;}$expire = time() + ($this->cache_expiration * 60);if (flock($fp, LOCK_EX)){fwrite($fp, $expire.'TS--->'.$output);flock($fp, LOCK_UN);}else{log_message('error', "Unable to secure a file lock for file at: ".$cache_path);return;}fclose($fp);@chmod($cache_path, FILE_WRITE_MODE);log_message('debug', "Cache file written: ".$cache_path);}//更新缓存文件function _display_cache(&$CFG, &$URI){$cache_path = ($CFG->item('cache_path') == '') ? APPPATH.'cache/' : $CFG->item('cache_path');// Build the file path.  The file name is an MD5 hash of the full URI$uri =$CFG->item('base_url').$CFG->item('index_page').$URI->uri_string;$filepath = $cache_path.md5($uri);if ( ! @file_exists($filepath)){return FALSE;}if ( ! $fp = @fopen($filepath, FOPEN_READ)){return FALSE;}flock($fp, LOCK_SH);$cache = '';if (filesize($filepath) > 0){$cache = fread($fp, filesize($filepath));}flock($fp, LOCK_UN);fclose($fp);// Strip out the embedded timestampif ( ! preg_match("/(\d+TS--->)/", $cache, $match)){return FALSE;}// Has the file expired? If so we'll delete it.if (time() >= trim(str_replace('TS--->', '', $match['1']))){if (is_really_writable($cache_path)){@unlink($filepath);log_message('debug', "Cache file has expired. File deleted");return FALSE;}}// Display the cache$this->_display(str_replace($match['0'], '', $cache));log_message('debug', "Cache file is current. Sending it to browser.");return TRUE;}}