CodeIgniter 核心代码阅读-输出文件Output.php

<?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 later
if (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 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 $CI object above
if ($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 data
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.
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 timestamp
if ( ! 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;
}

}