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

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Release： 2016-07-14 10:09:18
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[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 and tags  
            // we will remove them and add them back after we insert the profile data  
            // 如果存在标签，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("|.*?|is", $output))  
            {  
                $output  = preg_replace("|.*?|is", '', $output);  
                $output .= $CI->profiler->run();  
$output .= '';
      }  
        else  
                                                                 
$output .= $CI->profiler->run();
      }  
} }
// --------------------------------------------- -----------------------
// Does the controller contain a function named _output()?
// If so send the output there. Otherwise, echo it.
// If there is _output method in the controller, we call it directly
// If data is not sent directly to the browser
if (method_exists($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
* Generate a cache file
* @access public
* @param string
* @return void
*/
function _write_cache($output)
{
// Call super object
$CI =& get_instance();
// Find the cache path
$path = $CI->config->item('cache_path');
$cache_path = ($path == '') ? APPPATH.'cache/' : $path;
// If the cache path is not a folder or cannot be written, an error will be returned.
if ( ! is_dir($cache_path) OR ! is_really_writable($cache_path))
{
log_message('error', "Unable to write cache file: ".$cache_path);
return;
} }
// Get $uri
$uri = $CI->config->item('base_url').
$CI->config->item('index_page').
$CI->uri->uri_string();
// Generate cache file.
$cache_path .= md5($uri);
if ( ! $fp = @fopen($cache_path, FOPEN_WRITE_CREATE_DESTRUCTIVE))
{
log_message('error', "Unable to write cache file: ".$cache_path);
return;
} }
// Calculate cache file expiration time.
$expire = time() + ($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
* This method is called in CodeIgniter.php. This method is responsible for caching the output.
* If there is output when calling this method in CodeIgniter.php, then
* The execution of this request will end directly and the cached output will be responded directly.
*
* @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。  
// If it does not conform to this structure, it can be regarded as a non-CI cache file, or the file is damaged,
// Failed to obtain the cache content and returns 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.
// Determine whether the cache has expired, if it expires we will 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;
}
}
// END Output Class
/* End of file Output.php */
/* Location: ./system/core/Output.php */

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