CI framework source code reading---------Output.php_PHP tutorial

[php]  

/** 

 * 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 for sending final output to browser

* Responsible for sending the final output to the browser

* @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

* Current output string

*

* @var string

* @access protected

*/  

    protected $final_output;  

    /**

* Cache expiration time

* Cache expiration time

* @var int

* @access protected

*/  

    protected $cache_expiration = 0;  

    /**

* List of server headers

* Server header list

* @var array

* @access protected

*/  

    protected $headers          = array();  

    /** 

     * List of mime types 

     *  

     * @var array 

     * @access  protected 

     */  

    protected $mime_types       = array();  

    /**

* Determines wether profiler is enabled

* Whether to enable the analyzer

* @var book

* @access protected

*/  

    protected $enable_profiler  = FALSE;  

    /**

* Determines if output compression is enabled

* Whether to enable output compression

* @var bool

* @access protected

*/  

    protected $_zlib_oc         = FALSE;  

    /**

* List of profiler sections

* Analyzer list

*

* @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()

{

// Return the value of the configuration item zlib.output_compression and assign it to $this->_zlib_oc

// If the output compression function is turned on in the configuration item, the value of $this->_zlib_oc is on

$this->_zlib_oc = @ini_get('zlib.output_compression');

// Get mime types for later

// Get 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 is an array defined in mimes.php

$this->mime_types = $mimes;

log_message('debug', "Output Class Initialized");

}

//------------------------------------------------ -----------------------

/**

* Get Output

* Using this method, you can get the data to be output and save it

* Returns the current output string

* Returns the current output string

* @access public

* @return string

*/

function get_output()

{

return $this->final_output;

}

//------------------------------------------------ -----------------------

/**

* Set Output

*

* Sets the output string

* Set the output string

* @access public

* @param string

* @return void

*/

function set_output($output)

{

$this->final_output = $output;

return $this;

}

//------------------------------------------------ -----------------------

/**

* Append Output

* After the final output string, append data

* 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

* Using this method, allows you to set the header of the HTTP protocol that will be sent to the browser, which is equivalent to the standard function of PHP: header().

* Lets you set a server header which will be outputted with the final display.

* Allows you to set a server header for final display output.

* Note: If a file is cached, headers will not be sent. We need to figure 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

* Allows you to enable or disable the analyzer

* @access public

* @param bool

* @return void

*/  

    function enable_profiler($val = TRUE)  

    {  

        $this->enable_profiler = (is_bool($val)) ? $val : TRUE;  

  

        return $this;  

    }  

  

    // --------------------------------------------------------------------  

  

    /**

* Set Profiler Sections

* Set $this->_profiler_sections

* Allows override of default / config settings for Profiler section display

* Allows you to control (on/off) specific parts of the reviewer when it is enabled

*

* @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

* Set cache and cache time

* @access public

* @param integer where $time is the number of minutes you want the cache to be updated

* @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.

// Note: We use global because we cannot use $CI =& get_instance()

global $BM, $CFG;

// Grab the super object if we can.

// //Of course, if we can get the super controller, we’ll get it first.

if (class_exists('CI_Controller'))

{

$CI =& get_instance();

} }

// --------------------------------------------- -----------------------

// Set the output data

// Set output data

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

// If the cache time>0, the $CI super object exists and the _output method exists under the super object

// Call the _write_cache method to write a cache file

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

// Calculate code execution time and memory usage time

$elapsed = $BM->elapsed_time('total_execution_time_start', 'total_execution_time_end');

// If $this->parse_exec_vars is true, {elapsed_time}, {memory_usage} in the output will be output

// Replace with the calculated time.

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? Processing of compression transmission.

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 ( ! emptyempty($this->_profiler_sections))  

            {  

                $CI->profiler->set_sections($this->_profiler_sections);  

            }  

  

            // If the output data contains closing