CI框架源码翻阅-Output.php

<?php  if ( ! defined('BASEPATH')) exit('No direct script access allowed');/** * CodeIgniter * * An open source application development framework for PHP 5.1.6 or newer * * @package		CodeIgniter * @author		ExpressionEngine Dev Team * @copyright	Copyright (c) 2008 - 2011, EllisLab, Inc. * @license		http://codeigniter.com/user_guide/license.html * @link		http://codeigniter.com * @since		Version 1.0 * @filesource */// ------------------------------------/** * Output Class * * Responsible 负责 for sending final output to browser * 负责把最终的输出发送到浏览器 * @package		CodeIgniter * @subpackage	Libraries * @category	Output * @author		ExpressionEngine Dev Team * @link		http://codeigniter.com/user_guide/libraries/output.html */class CI_Output {	/**	 * Current output string	 * 当前输出的字符串	 *	 * @var string	 * @access 	protected	 */	protected $final_output;	/**	 * Cache expiration time	 * 缓存终结的时间	 * @var int	 * @access 	protected	 */	protected $cache_expiration	= 0;	/**	 * List of server headers	 * 服务器头列表	 * @var array	 * @access 	protected	 */	protected $headers			= array();	/**	 * List of mime types	 * 	 * @var array	 * @access 	protected	 */	protected $mime_types		= array();	/**	 * Determines wether profiler is enabled	 * 是否启用分析器	 * @var book	 * @access 	protected	 */	protected $enable_profiler	= FALSE;	/**	 * Determines if output compression is enabled	 * 是否开启输出压缩	 * @var bool	 * @access 	protected	 */	protected $_zlib_oc			= FALSE;	/**	 * List of profiler sections	 * 分析器列表	 *	 * @var array	 * @access 	protected	 */	protected $_profiler_sections = array();	/**	 * Whether or not to parse variables like {elapsed_time} and {memory_usage}	 * 是否解析变量{elapsed_time} and {memory_usage}	 * 注意文档说这里有错误详见http://codeigniter.org.cn/user_guide/libraries/output.html	 * 最下方	 * @var bool	 * @access 	protected	 */	protected $parse_exec_vars	= TRUE;	/**	 * Constructor	 *	 */	function __construct()	{		// 返回配置项zlib.output_compression的值并赋给$this->_zlib_oc 		// 如果配置项中开启了输出压缩功能则	$this->_zlib_oc 的值为on		$this->_zlib_oc = @ini_get('zlib.output_compression');		// Get mime types for later		// 获取mimetype		if (defined('ENVIRONMENT') AND file_exists(APPPATH.'config/'.ENVIRONMENT.'/mimes.php'))		{		    include APPPATH.'config/'.ENVIRONMENT.'/mimes.php';		}		else		{			include APPPATH.'config/mimes.php';		}				// $mimes 是mimes.php中定义的一个数组		$this->mime_types = $mimes;		log_message('debug', "Output Class Initialized");	}	// --------------------------------	/**	 * Get Output	 * 使用这个方法，你可以得到将要输出的数据，并把它保存起来	 * Returns the current output string	 * 返回当前输出的字符串	 * @access	public	 * @return	string	 */	function get_output()	{		return $this->final_output;	}	// --------------------------------	/**	 * Set Output	 *	 * Sets the output string	 * 设置输出的字符串	 * @access	public	 * @param	string	 * @return	void	 */	function set_output($output)	{		$this->final_output = $output;		return $this;	}	// --------------------------------	/**	 * Append Output	 * 在最终输出字符串后，追加数据	 * Appends data onto the output string	 * 	 * @access	public	 * @param	string	 * @return	void	 */	function append_output($output)	{		if ($this->final_output == '')		{			$this->final_output = $output;		}		else		{			$this->final_output .= $output;		}		return $this;	}	// --------------------------------	/**	 * Set Header	 * 使用此方法，允许你设置将会被发送到浏览器的HTTP协议的标头，作用相当于php的标准函数: header()。	 * Lets you set a server header which will be outputted with the final display.	 * 允许您设置一个服务器头用于最终的显示输出。	 * Note:  If a file is cached, headers will not be sent.  We need to figure 计算 out	 * how to permit header data to be saved with the cache data...	 *	 * @access	public	 * @param	string	 * @param 	bool	 * @return	void	 */	function set_header($header, $replace = TRUE)	{		// If zlib.output_compression is enabled it will compress the output,		// but it will not modify the content-length header to compensate 补偿 for		// the reduction减少 还原, causing the browser to hang waiting for more data.		// We'll just skip content-length in those cases.		if ($this->_zlib_oc && strncasecmp($header, 'content-length', 14) == 0)		{			return;		}		$this->headers[] = array($header, $replace);		return $this;	}	// --------------------------------	/**	 * Set Content Type Header	 * 设置Content-Type	 * @access	public	 * @param	string	extension of the file we're outputting	 * @return	void	 */	function set_content_type($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 $this;	}	// --------------------------------	/**	 * Set HTTP Status Header	 * moved to Common procedural functions in 1.7.2	 * 允许你手动设置服务器状态头(header)	 * @access	public	 * @param	int		the status code	 * @param	string	 * @return	void	 */	function set_status_header($code = 200, $text = '')	{		set_status_header($code, $text);		return $this;	}	// --------------------------------	/**	 * Enable/disable Profiler	 * 允许你开启或禁用分析器	 * @access	public	 * @param	bool	 * @return	void	 */	function enable_profiler($val = TRUE)	{		$this->enable_profiler = (is_bool($val)) ? $val : TRUE;		return $this;	}	// --------------------------------	/**	 * Set Profiler Sections	 * 设置$this->_profiler_sections	 * Allows override of default / config settings for Profiler section display	 * 允许你在评测器启用时，控制(开/关)其特定部分	 * 	 * @access	public	 * @param	array	 * @return	void	 */	function set_profiler_sections($sections)	{		foreach ($sections as $section => $enable)		{			$this->_profiler_sections[$section] = ($enable !== FALSE) ? TRUE : FALSE;		}		return $this;	}	// --------------------------------	/**	 * Set Cache	 * 设置缓存以及缓存时间 	 * @access	public	 * @param	integer 其中 $time 是你希望缓存更新的 分钟 数	 * @return	void	 */	function cache($time)	{		$this->cache_expiration = ( ! is_numeric($time)) ? 0 : $time;		return $this;	}	// --------------------------------	/**	 * Display Output	 * 显示输出	 * All "view" data is automatically put into this variable by the controller class:	 *	 * $this->final_output	 *	 * This function sends the finalized output data to the browser along	 * with any server headers and profile data.  It also stops the	 * benchmark timer so the page rendering speed and memory usage can be shown.	 *	 * @access	public	 * @param 	string	 * @return	mixed	 */	function _display($output = '')	{		// Note:  We use globals because we can't use $CI =& get_instance()		// since this function is sometimes called by the caching mechanism,		// which happens before the CI super object is available.		// 注意：我们使用global 是因为我们不能使用$CI =& get_instance() 		global $BM, $CFG;		// Grab the super object if we can.		// //当然如果可以拿到超级控制器，我们先拿过来。		if (class_exists('CI_Controller'))		{			$CI =& get_instance();		}		// --------------------------------		// Set the output data		// 设置输出数据		if ($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 $CI object above		// 如果缓存时间>0 ，$CI 超级对象存在并且超级对象下面存在_output 方法		// 调用_write_cache 方法，写一个缓存文件		if ($this->cache_expiration > 0 && isset($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		// 计算代码执行时间和内存使用时间		$elapsed = $BM->elapsed_time('total_execution_time_start', 'total_execution_time_end');		// 如果$this->parse_exec_vars为true，将输出中的{elapsed_time}，{memory_usage}		// 替换为计算出的时间。		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, $output);		}		// --------------------------------		// Is compression requested?压缩传输的处理。		if ($CFG->item('compress_output') === TRUE && $this->_zlib_oc == FALSE)		{			if (extension_loaded('zlib'))			{				if (isset($_SERVER['HTTP_ACCEPT_ENCODING']) AND strpos($_SERVER['HTTP_ACCEPT_ENCODING'], 'gzip') !== FALSE)				{					ob_start('ob_gzhandler');				}			}		}		// --------------------------------		// Are there any server headers to send?		// 有没有服务器头发送？		if (count($this->headers) > 0)		{			foreach ($this->headers as $header)			{				@header($header[0], $header[1]);			}		}		// --------------------------------		// Does the $CI object exist?		// If not we know we are dealing with a cache file so we'll		// simply echo out the data and exit.		// 如果没有$CI就证明当前是一个缓存的输出，我们只简单的发送数据并退出		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.		// 如果开启了性能分析我们就调用，		// 会生成一些报告到页面尾部用于辅助我们调试。		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 data			// 如果存在</body></html>标签，我们将删除，插入我们的性能分析代码后再添加回去			if (preg_match("|</body>.*?</html>|is", $output))			{				$output  = preg_replace("|</body>.*?</html>|is", '', $output);				$output .= $CI->profiler->run();				$output .= '</body></html>';			}			else			{				$output .= $CI->profiler->run();			}		}		// --------------------------------		// Does the controller contain a function named _output()?		// If so send the output there.  Otherwise, echo it.		// 如果控制器中有_output 这个方法我们直接调用		// 如果没有直接发送数据到浏览器		if (method_exists($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);	}	// --------------------------------	/**	 * Write a Cache File	 * 生成一个缓存文件	 * @access	public	 * @param 	string	 * @return	void	 */	function _write_cache($output)	{		// 调用超级对象		$CI =& get_instance();		// 找到缓存路径		$path = $CI->config->item('cache_path');		$cache_path = ($path == '') ? APPPATH.'cache/' : $path;		// 如果缓存路径不是一个文件夹或者不可写 ，报错返回。		if ( ! is_dir($cache_path) OR ! is_really_writable($cache_path))		{			log_message('error', "Unable to write cache file: ".$cache_path);			return;		}		// 获取$uri		$uri =	$CI->config->item('base_url').				$CI->config->item('index_page').				$CI->uri->uri_string();		// 生成缓存文件。		$cache_path .= md5($uri);		if ( ! $fp = @fopen($cache_path, FOPEN_WRITE_CREATE_DESTRUCTIVE))		{			log_message('error', "Unable to write cache file: ".$cache_path);			return;		}		// 计算缓存文件过期时间。		$expire = time() + ($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: ".$cache_path);	}	// --------------------------------	/**	 * Update/serve a cached file	 * 在CodeIgniter.php里面有调用此方法，此方法是负责缓存的输出，	 * 如果在CodeIgniter.php中调用此方法有输出，则	 * 本次请求的运行将直接结束，直接以缓存输出作为响应。	 * 	 * @access	public	 * @param 	object	config class	 * @param 	object	uri class	 * @return	void	 */	function _display_cache(&$CFG, &$URI)	{		// 取得保存缓存的路径		$cache_path = ($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		// 一条准确的路由都会对应一个缓存文件，缓存文件是对应路由字符串的md5密文。		$uri =	$CFG->item('base_url').				$CFG->item('index_page').				$URI->uri_string;		$filepath = $cache_path.md5($uri);		// 如果没有此缓存文件，获取缓存内容失败，则可以返回FALSE。		if ( ! @file_exists($filepath))		{			return FALSE;		}		// 如果有此缓存文件，但是无法读，获取缓存内容失败，同样返回FALSE。		if ( ! $fp = @fopen($filepath, FOPEN_READ))		{			return FALSE;		}		// 打开到缓存文件，并以$fp作为句柄。下一步先取得共享锁（读取）。		flock($fp, LOCK_SH);		$cache = '';		if (filesize($filepath) > 0)		{			$cache = fread($fp, filesize($filepath));		}		// 解锁		flock($fp, LOCK_UN);		// 关闭文件连接。		fclose($fp);		// 下面这个TS--->字样，只是因为CI的缓存文件里面的内容		// 是规定以数字＋TS--->开头而已。这个数字是代表创建时间。		// 如果不符合此结构，可视为非CI的缓存文件，或者文件已损坏，		// 获取缓存内容失败，返回FALSE。		// Strip out the embedded timestamp		if ( ! preg_match("/(\d+TS--->)/", $cache, $match))		{			return FALSE;		}		// Has the file expired? If so we'll delete it.		// 判断缓存是否过期，如果过期我们将删除它		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;	}}// END Output Class/* End of file Output.php *//* Location: ./system/core/Output.php */