CodeIgniter.php 引入的第七个核心文件($OUT)。输出类是个核心类,它的功能只有一个:发送 Web 页面内容到请求的浏览器。 如果你开启缓存,它也负责 缓存 你的 Web 页面。

缓存机制

通过源码可知,写在controller方法用的echo等输出内容是无法缓存下来的。因为Output只缓存参数 public $final_output; 存储的内容。而该参数只能由append_output参数(该参数在 load->view时调用。)

zlib.output_compression

对页面尽兴Gzip压缩

一般而言,页面文件开启gzip压缩以后,其体积可以减小60%~90%,对于文字类站点,可以节省下大量的带宽与用户等待时间。但是不论是iis还是apache默认都只压缩html类静态文件,对于php文件需要模块配置才可支持(iis7.5中开启动态+静态压缩也可以),于是利用php自身功能到达gzip的效果也成为一项合理的诉求。参考地址

Mime types

参考连接

字符串操作

字符串比较

strcmp strncmp strcasecmp strncasecmp

字符串解析

mixed sscanf ( string $str , string $format [, mixed &$... ] )

数组操作

mixed current ( array &$array )

array array_map ( callable $callback , array $arr1 [, array $... ] )

array_map() 返回一个数组,该数组包含了 arr1 中的所有单元经过 callback 作用过之后的单元。callback
接受的参数数目应该和传递给 array_map() 函数的数组数目一致。

mixed array_shift ( array &$array )

array_shift() 将 array 的第一个单元移出并作为结果返回,将 array
的长度减一并将所有其它单元向前移动一位。所有的数字键名将改为从零开始计数,文字键名将不变。

array headers_list ( void )

headers_list() will return a list of headers to be sent to the browser
/ client. To determine whether or not these headers have been sent
yet, use headers_sent().

array array_merge ( array $array1 [, array $... ] )

array_merge() 将一个或多个数组的单元合并起来,一个数组中的值附加在前一个数组的后面。返回作为结果的数组。

如果输入的数组中有相同的字符串键名,则该键名后面的值将覆盖前一个值。然而,如果数组包含数字键名,后面的值将不会覆盖原来的值,而是附加到后面。

如果只给了一个数组并且该数组是数字索引的,则键名会以连续方式重新索引。

bool ob_start ([ callback $output_callback [, int $chunk_size [, bool $erase ]]] )

此函数将打开输出缓冲。当输出缓冲激活后,脚本将不会输出内容(除http标头外),相反需要输出的内容被存储在内部缓冲区中。

参考地址

string ob_gzhandler ( string $buffer , int $mode )

ob_gzhandler()目的是用在ob_start()中作回调函数,以方便将gz
编码的数据发送到支持压缩页面的浏览器。在ob_gzhandler()真正发送压缩过的数据之前,该
函数会确定(判定)浏览器可以接受哪种类型内容编码(”gzip”,”deflate”,或者根本什么都不支持),然后 返回相应的输出。
所有可以发送正确头信息表明他自己可以接受压缩的网页的浏览器,都可以支持。 All browsers are supported since
it’s up to the browser to send the correct header saying that it
accepts compressed web pages. 如果一个浏览器不支持压缩过的页面,此函数返回FALSE。

bool flock ( resource $handle , int $operation [, int &$wouldblock ] )

flock() 允许执行一个简单的可以在任何平台中使用的读取/写入模型(包括大部分的 Unix 派生版和甚至是 Windows)。

array array_intersect_key ( array $array1 , array $array2 [, array $ ... ] )

array_intersect_key() 返回一个数组,该数组包含了所有出现在 array1 中并同时出现在所有其它参数数组中的键名的值。

array array_flip ( array $trans )

array_flip() 返回一个反转后的 array,例如 trans 中的键名变成了值,而 trans 中的值成了键名。

注意 trans 中的值需要能够作为合法的键名,例如需要是 integer 或者
string。如果值的类型不对将发出一个警告,并且有问题的键/值对将不会反转。

如果同一个值出现了多次,则最后一个键名将作为它的值,所有其它的都丢失了。

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<?php
/**
* CodeIgniter
*
* An open source application development framework for PHP
*
* This content is released under the MIT License (MIT)
*
* Copyright (c) 2014 - 2015, British Columbia Institute of Technology
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*
* @package CodeIgniter
* @author EllisLab Dev Team
* @copyright Copyright (c) 2008 - 2014, EllisLab, Inc. (http://ellislab.com/)
* @copyright Copyright (c) 2014 - 2015, British Columbia Institute of Technology (http://bcit.ca/)
* @license http://opensource.org/licenses/MIT MIT License
* @link http://codeigniter.com
* @since Version 1.0.0
* @filesource
*/
defined('BASEPATH') OR exit('No direct script access allowed');

/**
* Output Class
*
* Responsible for sending final output to the browser.
*
* @package CodeIgniter
* @subpackage Libraries
* @category Output
* @author EllisLab Dev Team
* @link http://codeigniter.com/user_guide/libraries/output.html
*/
class CI_Output {

/**
* Final output string
*
* @var string
*/
public $final_output;

/**
* Cache expiration time
*
* @var int
*/
public $cache_expiration = 0;

/**
* List of server headers
*
* @var array
*/
public $headers = array();

/**
* List of mime types
*
* @var array
*/
public $mimes = array();

/**
* Mime-type for the current page
*
* @var string
*/
protected $mime_type = 'text/html';

/**
* Enable Profiler flag
*
* @var bool
*/
public $enable_profiler = FALSE;

/**
* php.ini zlib.output_compression flag
*
* @var bool
*/
protected $_zlib_oc = FALSE;

/**
* CI output compression flag
*
* @var bool
*/
protected $_compress_output = FALSE;

/**
* List of profiler sections
*
* @var array
*/
protected $_profiler_sections = array();

/**
* Parse markers flag
*
* Whether or not to parse variables like {elapsed_time} and {memory_usage}.
*
* @var bool
*/
public $parse_exec_vars = TRUE;

/**
* Class constructor
*
* Determines whether zLib output compression will be used.
*
* @return void
*/
public function __construct()
{
//是否开启gizp压缩
$this->_zlib_oc = (bool) ini_get('zlib.output_compression');
$this->_compress_output = (
$this->_zlib_oc === FALSE
&& config_item('compress_output') === TRUE
&& extension_loaded('zlib')
);

// Get mime types for later
$this->mimes =& get_mimes();

log_message('info', 'Output Class Initialized');
}

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

/**
* Get Output
*
* Returns the current output string.
*
* @return string
*/
public function get_output()
{
return $this->final_output;
}

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

/**
* Set Output
*
* Sets the output string.
*
* @param string $output Output data
* @return CI_Output
*/
public function set_output($output)
{
$this->final_output = $output;
return $this;
}

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

/**
* Append Output
*
* Appends data onto the output string.
*
* @param string $output Data to append
* @return CI_Output
*/
public function append_output($output)
{
$this->final_output .= $output;
return $this;
}

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

/**
* Set Header
*
* Lets you set a server header which will be sent with the final output.
*
* Note: If a file is cached, headers will not be sent.
* @todo We need to figure out how to permit headers to be cached.
*
* @param string $header Header
* @param bool $replace Whether to replace the old header value, if already set
* @return CI_Output
*/
public function set_header($header, $replace = TRUE)
{
// 不再对 content-length 进行设置(如果开启了 zlib.output_compression)
// If zlib.output_compression is enabled it will compress the output,
// but it will not modify the content-length header to compensate for
// the reduction, causing the browser to hang waiting for more data.
// We'll just skip content-length in those cases.
if ($this->_zlib_oc && strncasecmp($header, 'content-length', 14) === 0)
{
return $this;
}

$this->headers[] = array($header, $replace);
return $this;
}

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

/**
* Set Content-Type Header
* 设置 mime type (Content-Type)
*
* @param string $mime_type Extension of the file we're outputting
* @param string $charset Character set (default: NULL)
* @return CI_Output
*/
public function set_content_type($mime_type, $charset = NULL)
{
if (strpos($mime_type, '/') === FALSE)
{
//.txt => text/plain
$extension = ltrim($mime_type, '.');

// Is this extension supported?
if (isset($this->mimes[$extension]))
{
$mime_type =& $this->mimes[$extension];

//取出数组第一个
if (is_array($mime_type))
{
$mime_type = current($mime_type);
}
}
}

$this->mime_type = $mime_type;

if (empty($charset))
{
$charset = config_item('charset');
}

$header = 'Content-Type: '.$mime_type
.(empty($charset) ? '' : '; charset='.$charset);

$this->headers[] = array($header, TRUE);
return $this;
}

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

/**
* Get Current Content-Type Header
* 从$this->headers取出content-type
*
* @return string 'text/html', if not already set
*/
public function get_content_type()
{
for ($i = 0, $c = count($this->headers); $i < $c; $i++)
{
if (sscanf($this->headers[$i][0], 'Content-Type: %[^;]', $content_type) === 1)
{
return $content_type;
}
}

return 'text/html';
}

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

/**
* Get Header
*
* @param string $header_name
* @return string
*/
public function get_header($header)
{
// Combine headers already sent with our batched headers
// 合并重复后者合并前者
$headers = array_merge(
// We only need [x][0] from our multi-dimensional array
// 取出 aaa: true 的 aaa
array_map('array_shift', $this->headers),
headers_list()
);

if (empty($headers) OR empty($header))
{
return NULL;
}

for ($i = 0, $c = count($headers); $i < $c; $i++)
{
if (strncasecmp($header, $headers[$i], $l = strlen($header)) === 0)
{
return trim(substr($headers[$i], $l+1));
}
}

return NULL;
}

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

/**
* Set HTTP Status Header
*
* As of version 1.7.2, this is an alias for common function
* set_status_header().
*
* @param int $code Status code (default: 200)
* @param string $text Optional message
* @return CI_Output
*/
public function set_status_header($code = 200, $text = '')
{
set_status_header($code, $text);
return $this;
}

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

/**
* Enable/disable Profiler
*
* @param bool $val TRUE to enable or FALSE to disable
* @return CI_Output
*/
public function enable_profiler($val = TRUE)
{
$this->enable_profiler = is_bool($val) ? $val : TRUE;
return $this;
}

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

/**
* Set Profiler Sections
* 程序分析器
*
* Allows override of default/config settings for
* Profiler section display.
*
* @param array $sections Profiler sections
* @return CI_Output
*/
public function set_profiler_sections($sections)
{
if (isset($sections['query_toggle_count']))
{
$this->_profiler_sections['query_toggle_count'] = (int) $sections['query_toggle_count'];
unset($sections['query_toggle_count']);
}

foreach ($sections as $section => $enable)
{
$this->_profiler_sections[$section] = ($enable !== FALSE);
}

return $this;
}

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

/**
* Set Cache
*
* @param int $time Cache expiration time in seconds
* @return CI_Output
*/
public function cache($time)
{
$this->cache_expiration = is_numeric($time) ? $time : 0;
return $this;
}

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

/**
* Display Output
*
* Processes and sends finalized output data to the browser along
* with any server headers and profile data. It also stops benchmark
* timers so the page rendering(显示) speed and memory usage can be shown.
*
* Note: All "view" data is automatically put into $this->final_output
* by controller class.
*
* @uses CI_Output::$final_output
* @param string $output Output data override
* @return void
*/
public function _display($output = '')
{
// Note: We use load_class() 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.
$BM =& load_class('Benchmark', 'core');
$CFG =& load_class('Config', 'core');

// Grab the super object if we can.
if (class_exists('CI_Controller', FALSE))
{
$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
// 统计时间
$elapsed = $BM->elapsed_time('total_execution_time_start', 'total_execution_time_end');

//渲染模版
if ($this->parse_exec_vars === TRUE)
{
$memory = round(memory_get_usage() / 1024 / 1024, 2).'MB';
$output = str_replace(array('{elapsed_time}', '{memory_usage}'), array($elapsed, $memory), $output);
}

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

// Is compression requested?
if (isset($CI) // This means that we're not serving a cache file, if we were, it would already be compressed
&& $this->_compress_output === TRUE
&& isset($_SERVER['HTTP_ACCEPT_ENCODING']) && strpos($_SERVER['HTTP_ACCEPT_ENCODING'], 'gzip') !== FALSE)
{
//打开输出缓冲区,此时没有将内容发送到客户端
ob_start('ob_gzhandler');
}

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

// Are there any server headers to send?
// 设置头部
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))
{
if ($this->_compress_output === TRUE)
{
if (isset($_SERVER['HTTP_ACCEPT_ENCODING']) && strpos($_SERVER['HTTP_ACCEPT_ENCODING'], 'gzip') !== FALSE)
{
header('Content-Encoding: gzip');
header('Content-Length: '.strlen($output));
}
else
{
// User agent doesn't support gzip compression,
// so we'll have to decompress our cache
$output = gzinflate(substr($output, 10, -8));
}
}

echo $output;
log_message('info', 'Final output sent to browser');
log_message('debug', 'Total execution time: '.$elapsed);
return;
}

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

// 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
$output = preg_replace('|</body>.*?</html>|is', '', $output, -1, $count).$CI->profiler->run();
if ($count > 0)
{
$output .= '</body></html>';
}
}

// 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('info', 'Final output sent to browser');
log_message('debug', 'Total execution time: '.$elapsed);
}

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

/**
* Write Cache
*
* @param string $output Output data to cache
* @return void
*/
public function _write_cache($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();

if (($cache_query_string = $CI->config->item('cache_query_string')) && ! empty($_SERVER['QUERY_STRING']))
{
if (is_array($cache_query_string))
{
$uri .= '?'.http_build_query(array_intersect_key($_GET, array_flip($cache_query_string)));
}
else
{
$uri .= '?'.$_SERVER['QUERY_STRING'];
}
}

$cache_path .= md5($uri);

if ( ! $fp = @fopen($cache_path, 'w+b'))
{
log_message('error', 'Unable to write cache file: '.$cache_path);
return;
}

if (flock($fp, LOCK_EX))
{
// If output compression is enabled, compress the cache
// itself, so that we don't have to do that each time
// we're serving it
if ($this->_compress_output === TRUE)
{
$output = gzencode($output);

if ($this->get_header('content-type') === NULL)
{
$this->set_content_type($this->mime_type);
}
}

$expire = time() + ($this->cache_expiration * 60);

// Put together our serialized info.
$cache_info = serialize(array(
'expire' => $expire,
'headers' => $this->headers
));

$output = $cache_info.'ENDCI--->'.$output;

for ($written = 0, $length = strlen($output); $written < $length; $written += $result)
{
if (($result = fwrite($fp, substr($output, $written))) === FALSE)
{
break;
}
}

flock($fp, LOCK_UN);
}
else
{
log_message('error', 'Unable to secure a file lock for file at: '.$cache_path);
return;
}

fclose($fp);

if (is_int($result))
{
chmod($cache_path, 0640);
log_message('debug', 'Cache file written: '.$cache_path);

// Send HTTP cache-control headers to browser to match file cache settings.
$this->set_cache_header($_SERVER['REQUEST_TIME'], $expire);
}
else
{
@unlink($cache_path);
log_message('error', 'Unable to write the complete cache content at: '.$cache_path);
}
}

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

/**
* Update/serve cached output
*
* @uses CI_Config
* @uses CI_URI
*
* @param object &$CFG CI_Config class instance
* @param object &$URI CI_URI class instance
* @return bool TRUE on success or FALSE on failure
*/
public 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;

if (($cache_query_string = $CFG->item('cache_query_string')) && ! empty($_SERVER['QUERY_STRING']))
{
if (is_array($cache_query_string))
{
$uri .= '?'.http_build_query(array_intersect_key($_GET, array_flip($cache_query_string)));
}
else
{
$uri .= '?'.$_SERVER['QUERY_STRING'];
}
}

$filepath = $cache_path.md5($uri);

if ( ! file_exists($filepath) OR ! $fp = @fopen($filepath, 'rb'))
{
return FALSE;
}

flock($fp, LOCK_SH);

$cache = (filesize($filepath) > 0) ? fread($fp, filesize($filepath)) : '';

flock($fp, LOCK_UN);
fclose($fp);

// Look for embedded serialized file info.
if ( ! preg_match('/^(.*)ENDCI--->/', $cache, $match))
{
return FALSE;
}

$cache_info = unserialize($match[1]);
$expire = $cache_info['expire'];

$last_modified = filemtime($filepath);

// Has the file expired?
// 过期
if ($_SERVER['REQUEST_TIME'] >= $expire && is_really_writable($cache_path))
{
// If so we'll delete it.
@unlink($filepath);
log_message('debug', 'Cache file has expired. File deleted.');
return FALSE;
}
else
{
// Or else send the HTTP cache control headers.
$this->set_cache_header($last_modified, $expire);
}

// Add headers from cache file.
foreach ($cache_info['headers'] as $header)
{
$this->set_header($header[0], $header[1]);
}

// Display the cache
$this->_display(substr($cache, strlen($match[0])));
log_message('debug', 'Cache file is current. Sending it to browser.');
return TRUE;
}

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

/**
* Delete cache
*
* @param string $uri URI string
* @return bool
*/
public function delete_cache($uri = '')
{
$CI =& get_instance();
$cache_path = $CI->config->item('cache_path');
if ($cache_path === '')
{
$cache_path = APPPATH.'cache/';
}

if ( ! is_dir($cache_path))
{
log_message('error', 'Unable to find cache path: '.$cache_path);
return FALSE;
}

if (empty($uri))
{
$uri = $CI->uri->uri_string();

// get 参数是否会影响缓存
if (($cache_query_string = $CI->config->item('cache_query_string')) && ! empty($_SERVER['QUERY_STRING']))
{
if (is_array($cache_query_string))
{
$uri .= '?'.http_build_query(array_intersect_key($_GET, array_flip($cache_query_string)));
}
else
{
$uri .= '?'.$_SERVER['QUERY_STRING'];
}
}
}

$cache_path .= md5($CI->config->item('base_url').$CI->config->item('index_page').ltrim($uri, '/'));

if ( ! @unlink($cache_path))
{
log_message('error', 'Unable to delete cache file for '.$uri);
return FALSE;
}

return TRUE;
}

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

/**
* Set Cache Header
*
* Set the HTTP headers to match the server-side file cache settings
* in order to reduce bandwidth.
*
* 最后一次缓存时间 过期时间(dead_line)
*
* @param int $last_modified Timestamp of when the page was last modified
* @param int $expiration Timestamp of when should the requested page expire from cache
* @return void
*/
public function set_cache_header($last_modified, $expiration)
{
//生存时间
$max_age = $expiration - $_SERVER['REQUEST_TIME'];

//如果时间一致,那么返回HTTP状态码304(不返回文件内容),客户端接到之后,就直接把本地缓存文件显示到浏览器中。 如果时间不一致,就返回HTTP状态码200和新的文件内容,客户端接到之后,会丢弃旧文件,把新文件缓存起来,并显示到浏览器中。
if (isset($_SERVER['HTTP_IF_MODIFIED_SINCE']) && $last_modified <= strtotime($_SERVER['HTTP_IF_MODIFIED_SINCE']))
{
//客户端已经执行了GET,但文件未变化
$this->set_status_header(304);
exit;
}
else
{
//过期了
header('Pragma: public');
//指示客户机可以接收生存期不大于指定时间(以秒为单位)的响应。
header('Cache-Control: max-age='.$max_age.', public');
//过期时间
header('Expires: '.gmdate('D, d M Y H:i:s', $expiration).' GMT');
//最后更新时间
header('Last-modified: '.gmdate('D, d M Y H:i:s', $last_modified).' GMT');
}
}

}