CI框架源码翻阅-Output.php

CI框架源码阅读---------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