CodeIgniter框架代码解析-Common.php
这个类是公共函数类，这里面的函数都非常经典，也是codeigniter的核心函数。
<?php if ( ! defined('BASEPATH')) exit('没有权限访问脚本');
/**
*判断PHP的版本号
*
* @access public
* @param string
* @return bool 当系统版本号等于或大于传入版本号参数$version的时候，返回TRUE
*/
function is_php($version = '5.0.0'){
static $_is_php;
$version = (string)$version;
if ( ! isset($_is_php[$version])){
$_is_php[$version] = (version_compare(PHP_VERSION, $version) < 0) ? FALSE : TRUE;
}
return $_is_php[$version];
}
// ------------------------------------------------------------------------
/**
* 测试文件可写性
*
*测试的时候区分环境，进行不同的操作
* @access private
* @return void
*/
function is_really_writable($file){
// 如果在Unix系统下，且safe_mode模块未开启 则执行 is_writable
if (DIRECTORY_SEPARATOR == '/' AND @ini_get("safe_mode") == FALSE){
return is_writable($file);
}
//如果在windows系统下，或者safe_mode模块设置未开启时，则执行以下函数
// 判断文件是否是一个目录，并写入一个文件，然后读它.
if (is_dir($file)){
$file = rtrim($file, '/').'/'.md5(mt_rand(1,100).mt_rand(1,100));
// FOPEN_WRITE_CREATE = "rb" 以写入方式打开，将文件指针指向文件末尾。如果文件不存在则尝试创建之。
//b的意思是强制以二进制方式写入
if (($fp = @fopen($file, FOPEN_WRITE_CREATE)) === FALSE){
return FALSE;
}
fclose($fp);
@chmod($file, DIR_WRITE_MODE);//改变文件模式
@unlink($file);
return TRUE;
}elseif (($fp = @fopen($file, FOPEN_WRITE_CREATE)) === FALSE){
return FALSE;
}
fclose($fp);
return TRUE;
}
// ------------------------------------------------------------------------
/**
* 加载并实例化类
*
* 这个函数是一个非常重要的函数，是系统的核心，它是一个引用类型，
*通过传递不同的参数，它能够实例化不同的类，然后返回这个类的引用
*
* @access public
* @param string 所需要加载的类名称
* @param string 类所在的文件夹，默认是libraries
* @param string 类的前缀
* @return object 返回类的引用
*/
function &load_class($class, $directory = 'libraries', $prefix = 'CI_'){
//定义成静态的方法是为了防止多次加载，从而节省资源
static $_classes = array();
// 类是否存在？如果存在，则返回该类
if (isset($_classes[$class])){
return $_classes[$class];
}
$name = FALSE;
// 首先在系统文件"system/libraries"下查看是否存在该文件
// 然后再到用户建立的应用程序文件夹"application/libraries"下查找该文件
foreach (array(BASEPATH, APPPATH) as $path){
if (file_exists($path.$directory.'/'.$class.EXT)){
$name = $prefix.$class;
if (class_exists($name) === FALSE){
require($path.$directory.'/'.$class.EXT);
}
break;
}
}
// 接着查找自定义类
if (file_exists(APPPATH.$directory.'/'.config_item('subclass_prefix').$class.EXT)){
$name = config_item('subclass_prefix').$class;
if (class_exists($name) === FALSE){
require(APPPATH.$directory.'/'.config_item('subclass_prefix').$class.EXT);
}
}
// 如果未找到类
if ($name === FALSE){
//在这里使用exit() 而不是使用show_error()，是为了避免再次加载函数，出现死循环
exit('无法找到指定的类: '.$class.EXT);
}
// 跟踪记录类的加载情况
is_loaded($class);
$_classes[$class] = new $name();
return $_classes[$class];
}
// --------------------------------------------------------------------
/**
* 跟踪记录类的加载情况
* 这个函数是在load_class调用
*
* @access public
* @return array
*/
function is_loaded($class = ''){
static $_is_loaded = array();
if ($class != ''){
$_is_loaded[strtolower($class)] = $class;
}
return $_is_loaded;
}
// ------------------------------------------------------------------------
/**
*
*获取配置文件config.php中的配置信息
*
* 这个函数能够在及时配置类还没实例化的情况下抓取配置文件
*
* @access private
* @return array
*/
function &get_config($replace = array()){
static $_config;
if (isset($_config)){
return $_config[0];
}
$file_path = APPPATH.'config/'.ENVIRONMENT.'/config'.EXT;
//判断文件是否存在，如果存在就引入
if ( ! file_exists($file_path)){
$file_path = APPPATH.'config/config'.EXT;
if ( ! file_exists($file_path)){
exit('配置文件不存在.');
}
}
require($file_path);
// 判断$config变量是否存在，且必须是array类型
if ( ! isset($config) OR ! is_array($config)){
exit('配置文件格式不正确.');
}
// 替换配置文件中的配置
if (count($replace) > 0){
foreach ($replace as $key => $val){
if (isset($config[$key])){
$config[$key] = $val;
}
}
}
return $_config[0] =& $config;
}
// ------------------------------------------------------------------------
/**
* 获取config.php配置文件中的单项配置
*
* @access public
* @return mixed
*/
function config_item($item){
static $_config_item = array();
if ( ! isset($_config_item[$item])){
$config =& get_config();
if ( ! isset($config[$item])){
return FALSE;
}
$_config_item[$item] = $config[$item];
}
return $_config_item[$item];
}
// ------------------------------------------------------------------------
/**
* 错误显示
*
*
* @access public
* @return void
*/
function show_error($message, $status_code = 500, $heading = 'An Error Was Encountered')
{
$_error =& load_class('Exceptions', 'core');
echo $_error->show_error($heading, $message, 'error_general', $status_code);
exit;
}
// ------------------------------------------------------------------------
/**
* 404 错误显示
*
* This function is similar to the show_error() function above
* However, instead of the standard error template it displays
* 404 errors.
*
* @access public
* @return void
*/
function show_404($page = '', $log_error = TRUE)
{
$_error =& load_class('Exceptions', 'core');
$_error->show_404($page, $log_error);
exit;
}
// ------------------------------------------------------------------------
/**
* 错误日志接口函数
*
* We use this as a simple mechanism to access the logging
* class and send messages to be logged.
*
* @access public
* @return void
*/
function log_message($level = 'error', $message, $php_error = FALSE)
{
static $_log;
if (config_item('log_threshold') == 0)
{
return;
}
$_log =& load_class('Log');
$_log->write_log($level, $message, $php_error);
}
// ------------------------------------------------------------------------
/**
* 设置HTTP状态头
*
* @access public
* @param int the status code
* @param string
* @return void
*/
function set_status_header($code = 200, $text = ''){
$stati = array(
200 => 'OK',
201 => 'Created',
202 => 'Accepted',
203 => 'Non-Authoritative Information',
204 => 'No Content',
205 => 'Reset Content',
206 => 'Partial Content',
300 => 'Multiple Choices',
301 => 'Moved Permanently',
302 => 'Found',
304 => 'Not Modified',
305 => 'Use Proxy',
307 => 'Temporary Redirect',
400 => 'Bad Request',
401 => 'Unauthorized',
403 => 'Forbidden',
404 => 'Not Found',
405 => 'Method Not Allowed',
406 => 'Not Acceptable',
407 => 'Proxy Authentication Required',
408 => 'Request Timeout',
409 => 'Conflict',
410 => 'Gone',
411 => 'Length Required',
412 => 'Precondition Failed',
413 => 'Request Entity Too Large',
414 => 'Request-URI Too Long',
415 => 'Unsupported Media Type',
416 => 'Requested Range Not Satisfiable',
417 => 'Expectation Failed',
500 => 'Internal Server Error',
501 => 'Not Implemented',
502 => 'Bad Gateway',
503 => 'Service Unavailable',
504 => 'Gateway Timeout',
505 => 'HTTP Version Not Supported'
);
if ($code == '' OR ! is_numeric($code))
{
show_error('Status codes must be numeric', 500);
}
if (isset($stati[$code]) AND $text == '')
{
$text = $stati[$code];
}
if ($text == '')
{
show_error('No status text available. Please check your status code number or supply your own message text.', 500);
}
$server_protocol = (isset($_SERVER['SERVER_PROTOCOL'])) ? $_SERVER['SERVER_PROTOCOL'] : FALSE;
if (substr(php_sapi_name(), 0, 3) == 'cgi')
{
header("Status: {$code} {$text}", TRUE);
}
elseif ($server_protocol == 'HTTP/1.1' OR $server_protocol == 'HTTP/1.0')
{
header($server_protocol." {$code} {$text}", TRUE, $code);
}
else
{
header("HTTP/1.1 {$code} {$text}", TRUE, $code);
}
}
// --------------------------------------------------------------------
/**
* 自定义错误处理函数
*
* This is the custom exception handler that is declaired at the top
* of Codeigniter.php. The main reason we use this is to permit
* PHP errors to be logged in our own log files since the user may
* not have access to server logs. Since this function
* effectively intercepts PHP errors, however, we also need
* to display errors based on the current error_reporting level.
* We do that with the use of a PHP error template.
*
* @access private
* @return void
*/
function _exception_handler($severity, $message, $filepath, $line)
{
// We don't bother with "strict" notices since they tend to fill up
// the log file with excess information that isn't normally very helpful.
// For example, if you are running PHP 5 and you use version 4 style
// class functions (without prefixes like "public", "private", etc.)
// you'll get notices telling you that these have been deprecated.
if ($severity == E_STRICT)
{
return;
}
$_error =& load_class('Exceptions', 'core');
// Should we display the error? We'll get the current error_reporting
// level and add its bits with the severity bits to find out.
if (($severity & error_reporting()) == $severity)
{
$_error->show_php_error($severity, $message, $filepath, $line);
}
// Should we log the error? No? We're done...
if (config_item('log_threshold') == 0)
{
return;
}
$_error->log_exception($severity, $message, $filepath, $line);
}
// --------------------------------------------------------------------
/**
* Remove Invisible Characters
*
* This prevents sandwiching null characters
* between ascii characters, like Java\0script.
*
* @access public
* @param string
* @return string
*/
function remove_invisible_characters($str)
{
static $non_displayables;
if ( ! isset($non_displayables))
{
// every control character except newline (dec 10), carriage return (dec 13), and horizontal tab (dec 09),
$non_displayables = array(
'/%0[0-8bcef]/', // url encoded 00-08, 11, 12, 14, 15
'/%1[0-9a-f]/', // url encoded 16-31
'/[\x00-\x08]/', // 00-08
'/\x0b/', '/\x0c/', // 11, 12
'/[\x0e-\x1f]/' // 14-31
);
}
do
{
$cleaned = $str;
$str = preg_replace($non_displayables, '', $str);
}
while ($cleaned != $str);
return $str;
}
/* End of file Common.php */
/* Location: ./system/core/Common.php */