php优秀框架codeigniter学习系列——common.php

　　文件位于system/core/common.php，是框架核心文件。

　　该文件中定义了一系列的函数，都是框架运行中经常需要用到的。下面逐一介绍。

is_php

 1     /**
 2      * Determines if the current version of PHP is equal to or greater than the supplied value
 3      *
 4      * @param    string
 5      * @return    bool    TRUE if the current version is $version or higher
 6      */
 7     function is_php($version)
 8     {
 9         static $_is_php;
10         $version = (string) $version;
11 
12         if ( ! isset($_is_php[$version]))
13         {
14             $_is_php[$version] = version_compare(PHP_VERSION, $version, '>=');
15         }
16 
17         return $_is_php[$version];
18     }
19 }

　　该函数用于进行php版本比较，如果运行的php版本大于等于输入的php版本参数，则返回true。这里建立了一个$is_php静态数组，把新版本参数比较的结果存在数组里，如果再有类似的版本参数传入，不用比较，直接返回结果。是一种空间换时间的做法。

is_really_writable

 1     /**
 2      * Tests for file writability
 3      *
 4      * is_writable() returns TRUE on Windows servers when you really can't write to
 5      * the file, based on the read-only attribute. is_writable() is also unreliable
 6      * on Unix servers if safe_mode is on.
 7      *
 8      * @link    https://bugs.php.net/bug.php?id=54709
 9      * @param    string
10      * @return    bool
11      */
12     function is_really_writable($file)
13     {
14         // If we're on a Unix server with safe_mode off we call is_writable
15                 //用DIRECTORY_SEPARATOR === '/'来判断是unix系统，
16         if (DIRECTORY_SEPARATOR === '/' && (is_php('5.4') OR ! ini_get('safe_mode')))
17         {
18             return is_writable($file);
19         }
20 
21         /* For Windows servers and safe_mode "on" installations we'll actually
22          * write a file then read it. Bah...
23                  * 对于windows操作系统和安全模式的处理方法
24          */
25         if (is_dir($file))//对于目录
26         {
27             $file = rtrim($file, '/').'/'.md5(mt_rand());
28             if (($fp = @fopen($file, 'ab')) === FALSE)
29             {
30                 return FALSE;
31             }
32 
33             fclose($fp);
34             @chmod($file, 0777);
35             @unlink($file);
36             return TRUE;
37         }
38         elseif ( ! is_file($file) OR ($fp = @fopen($file, 'ab')) === FALSE)//对于文件
39         {
40             return FALSE;
41         }
42 
43         fclose($fp);
44         return TRUE;
45     }

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　　该函数用于判断文件或目录是否可写。

　　对于linux系统未使用安全模式的情况，直接调用php函数is_writable($file)即可。

　　对于windows系统和使用安全模式的linux系统则根据是文件夹还是文件采取不同的方式：文件夹是在看是否可在里面新建一个可读写的文件；文件是看是否可读写打开。　　

&load_class

 1     /**
 2      * Class registry
 3      *
 4      * This function acts as a singleton. If the requested class does not
 5      * exist it is instantiated and set to a static variable. If it has
 6      * previously been instantiated the variable is returned.
 7      *
 8      * @param    string    the class name being requested
 9      * @param    string    the directory where the class should be found
10      * @param    mixed    an optional argument to pass to the class constructor
11      * @return    object
12      */
13     function &load_class($class, $directory = 'libraries', $param = NULL)
14     {
15         static $_classes = array();
16 
17         // Does the class exist? If so, we're done...
18         if (isset($_classes[$class]))
19         {
20             return $_classes[$class];
21         }
22 
23         $name = FALSE;
24 
25         // Look for the class first in the local application/libraries folder
26         // then in the native system/libraries folder
27         foreach (array(APPPATH, BASEPATH) as $path)
28         {
29             if (file_exists($path.$directory.'/'.$class.'.php'))
30             {
31                 $name = 'CI_'.$class;
32 
33                 if (class_exists($name, FALSE) === FALSE)
34                 {
35                     require_once($path.$directory.'/'.$class.'.php');
36                 }
37 
38                 break;
39             }
40         }
41 
42         // Is the request a class extension? If so we load it too
43         if (file_exists(APPPATH.$directory.'/'.config_item('subclass_prefix').$class.'.php'))
44         {
45             $name = config_item('subclass_prefix').$class;
46 
47             if (class_exists($name, FALSE) === FALSE)
48             {
49                 require_once(APPPATH.$directory.'/'.$name.'.php');
50             }
51         }
52 
53         // Did we find the class?
54         if ($name === FALSE)
55         {
56             // Note: We use exit() rather than show_error() in order to avoid a
57             // self-referencing loop with the Exceptions class
58             set_status_header(503);
59             echo 'Unable to locate the specified class: '.$class.'.php';
60             exit(5); // EXIT_UNK_CLASS
61         }
62 
63         // Keep track of what we just loaded
64         is_loaded($class);
65 
66         $_classes[$class] = isset($param)
67             ? new $name($param)
68             : new $name();
69         return $_classes[$class];
70     }
71 }

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　　该函数用于类的注册，核心函数。

　　这个函数维护一个单例模式，即如果请求注册的类$class已经被实例化过了，则把保存的实例化对象返回，如果没有实例化过，就实例化该类。这个做法避免新建大量的对象，减少内存消耗，也减少了框架使用对象的维护成本，避免使用的混乱。

　　在搜索类文件的时候，既会搜索系统的类文件，也会搜索用户自定义的类文件。用户自定义类名需要定义统一的前缀，这个前缀在application/config/config.php文件的subclass_prefix变量中定义。

　　该函数前面有一个&，表明是引用传递返回值。即返回的对象以后发生变化的时候，在这个函数中定义的$_classes[$class]也会发生变化。参考知乎上的解释。

&is_loaded($class = '')

    /**
     * Keeps track of which libraries have been loaded. This function is
     * called by the load_class() function above
     *
     * @param    string
     * @return    array
     */
    function &is_loaded($class = '')
    {
        static $_is_loaded = array();

        if ($class !== '')
        {
            $_is_loaded[strtolower($class)] = $class;
        }
        return $_is_loaded;
    }

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　　该函数可以获取已经在load_class函数中注册的类名数组，也可以往类名数组中添加一个已经注册的类名。使用引用传递返回值。

&get_config(Array $replace = array())

 1     /**
 2      * Loads the main config.php file
 3      *
 4      * This function lets us grab the config file even if the Config class
 5      * hasn't been instantiated yet
 6      *
 7      * @param    array
 8      * @return    array
 9      */
10     function &get_config(Array $replace = array())
11     {
12         static $config;
13 
14         if (empty($config))
15         {
16             $file_path = APPPATH.'config/config.php';
17             $found = FALSE;
18             if (file_exists($file_path))
19             {
20                 $found = TRUE;
21                 require($file_path);
22             }
23 
24             // Is the config file in the environment folder?
25             if (file_exists($file_path = APPPATH.'config/'.ENVIRONMENT.'/config.php'))
26             {
27                 require($file_path);
28             }
29             elseif ( ! $found)
30             {
31                 set_status_header(503);
32                 echo 'The configuration file does not exist.';
33                 exit(3); // EXIT_CONFIG
34             }
35 
36             // Does the $config array exist in the file?
37             if ( ! isset($config) OR ! is_array($config))
38             {
39                 set_status_header(503);
40                 echo 'Your config file does not appear to be formatted correctly.';
41                 exit(3); // EXIT_CONFIG
42             }
43         }
44 
45         // Are any values being dynamically added or replaced?
46         foreach ($replace as $key => $val)
47         {
48             $config[$key] = $val;
49         }
50 
51         return $config;
52     }
53 }

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　　该函数用来加载application/config/config.php中的$config数组变量。当然，如果存在，也加载用户根据环境定义的config.php文件。

　　config.php文件中定义了一些系统和应用程序的设置，包括使用何种编码，是否采用csrf,自定义的类的类名前缀等等。

同时，使用该函数通过$replace也可以追加一些设置。

　　该函数使用静态局部变量数组$config来存储。使用引用传递返回值。

config_item($item)

 1     /**
 2      * Returns the specified config item
 3      *
 4      * @param    string
 5      * @return    mixed
 6      */
 7     function config_item($item)
 8     {
 9         static $_config;
10 
11         if (empty($_config))
12         {
13             // references cannot be directly assigned to static variables, so we use an array
14             $_config[0] =& get_config();
15         }
16 
17         return isset($_config[0][$item]) ? $_config[0][$item] : NULL;
18     }

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　　该函数用于获取某一个具体的在get_config()中定义的$config数组的值。

&get_mimes()

 1     /**
 2      * Returns the MIME types array from config/mimes.php
 3      *
 4      * @return    array
 5      */
 6     function &get_mimes()
 7     {
 8         static $_mimes;
 9 
10         if (empty($_mimes))
11         {
12             $_mimes = file_exists(APPPATH.'config/mimes.php')
13                 ? include(APPPATH.'config/mimes.php')
14                 : array();
15 
16             if (file_exists(APPPATH.'config/'.ENVIRONMENT.'/mimes.php'))
17             {
18                 $_mimes = array_merge($_mimes, include(APPPATH.'config/'.ENVIRONMENT.'/mimes.php'));
19             }
20         }
21 
22         return $_mimes;
23     }

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　　该函数用于获取在application/config/mimes.php中定义的mime类型数组。主要用于文件上传时候的检测。

is_https()

 1     /**
 2      * Is HTTPS?
 3      *
 4      * Determines if the application is accessed via an encrypted
 5      * (HTTPS) connection.
 6      *
 7      * @return    bool
 8      */
 9     function is_https()
10     {
11         if ( ! empty($_SERVER['HTTPS']) && strtolower($_SERVER['HTTPS']) !== 'off')
12         {
13             return TRUE;
14         }
15         elseif (isset($_SERVER['HTTP_X_FORWARDED_PROTO']) && strtolower($_SERVER['HTTP_X_FORWARDED_PROTO']) === 'https')
16         {
17             return TRUE;
18         }
19         elseif ( ! empty($_SERVER['HTTP_FRONT_END_HTTPS']) && strtolower($_SERVER['HTTP_FRONT_END_HTTPS']) !== 'off')
20         {
21             return TRUE;
22         }
23 
24         return FALSE;
25     }

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　　该函数判断请求是否是http请求。

is_cli()

 1     /**
 2      * Is CLI?
 3      *
 4      * Test to see if a request was made from the command line.
 5      *
 6      * @return     bool
 7      */
 8     function is_cli()
 9     {
10         return (PHP_SAPI === 'cli' OR defined('STDIN'));
11     }

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　　该函数用于判断请求是否是命令行方式。

show_error($message, $status_code = 500, $heading = 'An Error Was Encountered')

 1     /**
 2      * Error Handler
 3      *
 4      * This function lets us invoke the exception class and
 5      * display errors using the standard error template located
 6      * in application/views/errors/error_general.php
 7      * This function will send the error page directly to the
 8      * browser and exit.
 9      *
10      * @param    string
11      * @param    int
12      * @param    string
13      * @return    void
14      */
15     function show_error($message, $status_code = 500, $heading = 'An Error Was Encountered')
16     {
17         $status_code = abs($status_code);//取绝对值
18         if ($status_code < 100)
19         {
20             $exit_status = $status_code + 9; // 9 is EXIT__AUTO_MIN
21             $status_code = 500;
22         }
23         else
24         {
25             $exit_status = 1; // EXIT_ERROR
26         }
27 
28         $_error =& load_class('Exceptions', 'core');
29         echo $_error->show_error($heading, $message, 'error_general', $status_code);
30         exit($exit_status);
31     }

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　　该函数用于主动显示一个错误提示给用户，无论是命令行模式还是浏览器显示。调用的是Exceptions类的show_error方法。

show_404($page = '', $log_error = TRUE)

 1     /**
 2      * 404 Page Handler
 3      *
 4      * This function is similar to the show_error() function above
 5      * However, instead of the standard error template it displays
 6      * 404 errors.
 7      *
 8      * @param    string
 9      * @param    bool
10      * @return    void
11      */
12     function show_404($page = '', $log_error = TRUE)
13     {
14         $_error =& load_class('Exceptions', 'core');
15         $_error->show_404($page, $log_error);
16         exit(4); // EXIT_UNKNOWN_FILE
17     }

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　　该函数用于主动显示一个404错误给用户，无论是命令行模式还是浏览器显示。调用的是Exceptions类的show_404方法。

log_message($level, $message)

 1     /**
 2      * Error Logging Interface
 3      *
 4      * We use this as a simple mechanism to access the logging
 5      * class and send messages to be logged.
 6      *
 7      * @param    string    the error level: 'error', 'debug' or 'info'
 8      * @param    string    the error message
 9      * @return    void
10      */
11     function log_message($level, $message)
12     {
13         static $_log;
14 
15         if ($_log === NULL)
16         {
17             // references cannot be directly assigned to static variables, so we use an array
18             $_log[0] =& load_class('Log', 'core');
19         }
20 
21         $_log[0]->write_log($level, $message);
22     }

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　　该函数用于记录日志。常用的函数。日志分Error，Debug，Info三个级别。调用的是Log类的write_log方法。

set_status_header($code = 200, $text = '')

 1     /**
 2      * Set HTTP Status Header
 3      *
 4      * @param    int    the status code
 5      * @param    string
 6      * @return    void
 7      */
 8     function set_status_header($code = 200, $text = '')
 9     {
10         if (is_cli())
11         {
12             return;
13         }
14 
15         if (empty($code) OR ! is_numeric($code))
16         {
17             show_error('Status codes must be numeric', 500);
18         }
19 
20         if (empty($text))
21         {
22             is_int($code) OR $code = (int) $code;
23             $stati = array(
24                 100    => 'Continue',
25                 101    => 'Switching Protocols',
26 
27                 200    => 'OK',
28                 201    => 'Created',
29                 202    => 'Accepted',
30                 203    => 'Non-Authoritative Information',
31                 204    => 'No Content',
32                 205    => 'Reset Content',
33                 206    => 'Partial Content',
34 
35                 300    => 'Multiple Choices',
36                 301    => 'Moved Permanently',
37                 302    => 'Found',
38                 303    => 'See Other',
39                 304    => 'Not Modified',
40                 305    => 'Use Proxy',
41                 307    => 'Temporary Redirect',
42 
43                 400    => 'Bad Request',
44                 401    => 'Unauthorized',
45                 402    => 'Payment Required',
46                 403    => 'Forbidden',
47                 404    => 'Not Found',
48                 405    => 'Method Not Allowed',
49                 406    => 'Not Acceptable',
50                 407    => 'Proxy Authentication Required',
51                 408    => 'Request Timeout',
52                 409    => 'Conflict',
53                 410    => 'Gone',
54                 411    => 'Length Required',
55                 412    => 'Precondition Failed',
56                 413    => 'Request Entity Too Large',
57                 414    => 'Request-URI Too Long',
58                 415    => 'Unsupported Media Type',
59                 416    => 'Requested Range Not Satisfiable',
60                 417    => 'Expectation Failed',
61                 422    => 'Unprocessable Entity',
62                 426    => 'Upgrade Required',
63                 428    => 'Precondition Required',
64                 429    => 'Too Many Requests',
65                 431    => 'Request Header Fields Too Large',
66 
67                 500    => 'Internal Server Error',
68                 501    => 'Not Implemented',
69                 502    => 'Bad Gateway',
70                 503    => 'Service Unavailable',
71                 504    => 'Gateway Timeout',
72                 505    => 'HTTP Version Not Supported',
73                 511    => 'Network Authentication Required',
74             );
75 
76             if (isset($stati[$code]))
77             {
78                 $text = $stati[$code];
79             }
80             else
81             {
82                 show_error('No status text available. Please check your status code number or supply your own message text.', 500);
83             }
84         }
85 
86         if (strpos(PHP_SAPI, 'cgi') === 0)
87         {
88             header('Status: '.$code.' '.$text, TRUE);
89             return;
90         }
91 
92         $server_protocol = (isset($_SERVER['SERVER_PROTOCOL']) && in_array($_SERVER['SERVER_PROTOCOL'], array('HTTP/1.0', 'HTTP/1.1', 'HTTP/2'), TRUE))
93             ? $_SERVER['SERVER_PROTOCOL'] : 'HTTP/1.1';
94         header($server_protocol.' '.$code.' '.$text, TRUE, $code);
95     }

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　　手动设置返回的http头，如果设置的是“500”。那么浏览器解析的Status Code就是500。

_error_handler($severity, $message, $filepath, $line)

 1     /**
 2      * Error Handler
 3      *
 4      * This is the custom error handler that is declared at the (relative)
 5      * top of CodeIgniter.php. The main reason we use this is to permit
 6      * PHP errors to be logged in our own log files since the user may
 7      * not have access to server logs. Since this function effectively
 8      * intercepts PHP errors, however, we also need to display errors
 9      * based on the current error_reporting level.
10      * We do that with the use of a PHP error template.
11      *
12      * @param    int    $severity
13      * @param    string    $message
14      * @param    string    $filepath
15      * @param    int    $line
16      * @return    void
17      */
18     function _error_handler($severity, $message, $filepath, $line)
19     {
20         $is_error = (((E_ERROR | E_PARSE | E_COMPILE_ERROR | E_CORE_ERROR | E_USER_ERROR) & $severity) === $severity);
21 
22         // When an error occurred, set the status header to '500 Internal Server Error'
23         // to indicate to the client something went wrong.
24         // This can't be done within the $_error->show_php_error method because
25         // it is only called when the display_errors flag is set (which isn't usually
26         // the case in a production environment) or when errors are ignored because
27         // they are above the error_reporting threshold.
28         if ($is_error)
29         {
30             set_status_header(500);
31         }
32 
33         // Should we ignore the error? We'll get the current error_reporting
34         // level and add its bits with the severity bits to find out.
35         if (($severity & error_reporting()) !== $severity)
36         {
37             return;
38         }
39 
40         $_error =& load_class('Exceptions', 'core');
41         $_error->log_exception($severity, $message, $filepath, $line);
42 
43         // Should we display the error?
44         if (str_ireplace(array('off', 'none', 'no', 'false', 'null'), '', ini_get('display_errors')))
45         {
46             $_error->show_php_error($severity, $message, $filepath, $line);
47         }
48 
49         // If the error is fatal, the execution of the script should be stopped because
50         // errors can't be recovered from. Halting the script conforms with PHP's
51         // default error handling. See http://www.php.net/manual/en/errorfunc.constants.php
52         if ($is_error)
53         {
54             exit(1); // EXIT_ERROR
55         }
56     }

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　　该函数是在CodeIgniter.php中使用set_error_handler设置的用户自定义错误处理函数。该函数用于处理脚本中出现的错误。值得说明的是，以下级别的错误不能由用户定义的函数来处理： E_ERROR、 E_PARSE、 E_CORE_ERROR、 E_CORE_WARNING、 E_COMPILE_ERROR、 E_COMPILE_WARNING。所以即使不小心进入了这个方法，也需要屏蔽掉。

　　对于在函数前加了@屏蔽warning的函数，也会进入这个方法。但是它的error_reporting()返回值是0，而不管系统设置的是什么。可以由此来判断直接返回，不做处理。

　　$severity包含了错误的级别，是一个 integer。

　　调用Exceptions类的show_php_error方法。

_exception_handler($exception)

 1     /**
 2      * Exception Handler
 3      *
 4      * Sends uncaught exceptions to the logger and displays them
 5      * only if display_errors is On so that they don't show up in
 6      * production environments.
 7      *
 8      * @param    Exception    $exception
 9      * @return    void
10      */
11     function _exception_handler($exception)
12     {
13         $_error =& load_class('Exceptions', 'core');
14         $_error->log_exception('error', 'Exception: '.$exception->getMessage(), $exception->getFile(), $exception->getLine());
15 
16         is_cli() OR set_status_header(500);
17         // Should we display the error?
18         if (str_ireplace(array('off', 'none', 'no', 'false', 'null'), '', ini_get('display_errors')))
19         {
20             $_error->show_exception($exception);
21         }
22 
23         exit(1); // EXIT_ERROR
24     }

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　　该函数是在CodeIgniter.php中使用set_exception_handler设置的用户自定义异常处理函数。该函数是记录异常到日志中，并且展示给用户看到该异常。

　　set_error_handler和set_exception_handler的不同参见网上资料。

_shutdown_handler()

 1     /**
 2      * Shutdown Handler
 3      *
 4      * This is the shutdown handler that is declared at the top
 5      * of CodeIgniter.php. The main reason we use this is to simulate
 6      * a complete custom exception handler.
 7      *
 8      * E_STRICT is purposively neglected because such events may have
 9      * been caught. Duplication or none? None is preferred for now.
10      *
11      * @link    http://insomanic.me.uk/post/229851073/php-trick-catching-fatal-errors-e-error-with-a
12      * @return    void
13      */
14     function _shutdown_handler()
15     {
16         $last_error = error_get_last();
17         if (isset($last_error) &&
18             ($last_error['type'] & (E_ERROR | E_PARSE | E_CORE_ERROR | E_CORE_WARNING | E_COMPILE_ERROR | E_COMPILE_WARNING)))
19         {
20             _error_handler($last_error['type'], $last_error['message'], $last_error['file'], $last_error['line']);
21         }
22     }

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　　该函数是在CodeIgniter.php中使用register_shutdown_function 注册的会在php中止时执行的函数。

remove_invisible_characters($str, $url_encoded = TRUE)　　

 1     /**
 2      * Remove Invisible Characters
 3      *
 4      * This prevents sandwiching null characters
 5      * between ascii characters, like Java\0script.
 6      *
 7      * @param    string
 8      * @param    bool
 9      * @return    string
10      */
11     function remove_invisible_characters($str, $url_encoded = TRUE)
12     {
13         $non_displayables = array();
14 
15         // every control character except newline (dec 10),
16         // carriage return (dec 13) and horizontal tab (dec 09)
17         if ($url_encoded)
18         {
19             $non_displayables[] = '/%0[0-8bcef]/i';    // url encoded 00-08, 11, 12, 14, 15
20             $non_displayables[] = '/%1[0-9a-f]/i';    // url encoded 16-31
21             $non_displayables[] = '/%7f/i';    // url encoded 127
22         }
23 
24         $non_displayables[] = '/[\x00-\x08\x0B\x0C\x0E-\x1F\x7F]+/S';    // 00-08, 11, 12, 14-31, 127
25 
26         do
27         {
28             $str = preg_replace($non_displayables, '', $str, -1, $count);
29         }
30         while ($count);
31 
32         return $str;
33     }

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　　该函数用于清除字符串中的不可见字符。 $non_displayables[] = '/[\x00-\x08\x0B\x0C\x0E-\x1F\x7F]+/S'; 会匹配ascII中00-08, 11, 12, 14-31, 127的字符，这些字符都是不可见的。参见ascII字符表。

html_escape($var, $double_encode = TRUE)

 1     /**
 2      * Returns HTML escaped variable.
 3      *
 4      * @param    mixed    $var        The input string or array of strings to be escaped.
 5      * @param    bool    $double_encode    $double_encode set to FALSE prevents escaping twice.
 6      * @return    mixed            The escaped string or array of strings as a result.
 7      */
 8     function html_escape($var, $double_encode = TRUE)
 9     {
10         if (empty($var))
11         {
12             return $var;
13         }
14 
15         if (is_array($var))
16         {
17             foreach (array_keys($var) as $key)
18             {
19                 $var[$key] = html_escape($var[$key], $double_encode);
20             }
21 
22             return $var;
23         }
24 
25         return htmlspecialchars($var, ENT_QUOTES, config_item('charset'), $double_encode);
26     }

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　　该函数用于将字符串或者字符串数组转换为html实体。

_stringify_attributes($attributes, $js = FALSE)

 1     /**
 2      * Stringify attributes for use in HTML tags.
 3      *
 4      * Helper function used to convert a string, array, or object
 5      * of attributes to a string.
 6      *
 7      * @param    mixed    string, array, object
 8      * @param    bool
 9      * @return    string
10      */
11     function _stringify_attributes($attributes, $js = FALSE)
12     {
13         $atts = NULL;
14 
15         if (empty($attributes))
16         {
17             return $atts;
18         }
19 
20         if (is_string($attributes))
21         {
22             return ' '.$attributes;
23         }
24 
25         $attributes = (array) $attributes;
26 
27         foreach ($attributes as $key => $val)
28         {
29             $atts .= ($js) ? $key.'='.$val.',' : ' '.$key.'="'.$val.'"';
30         }
31 
32         return rtrim($atts, ',');
33     }

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　　将一个字符串属性，数组属性或者对象属性转换为一个字符串。主要用于在显示html页面的时候使用。

function_usable($function_name)

 1     /**
 2      * Function usable
 3      *
 4      * Executes a function_exists() check, and if the Suhosin PHP
 5      * extension is loaded - checks whether the function that is
 6      * checked might be disabled in there as well.
 7      *
 8      * This is useful as function_exists() will return FALSE for
 9      * functions disabled via the *disable_functions* php.ini
10      * setting, but not for *suhosin.executor.func.blacklist* and
11      * *suhosin.executor.disable_eval*. These settings will just
12      * terminate script execution if a disabled function is executed.
13      *
14      * The above described behavior turned out to be a bug in Suhosin,
15      * but even though a fix was committed for 0.9.34 on 2012-02-12,
16      * that version is yet to be released. This function will therefore
17      * be just temporary, but would probably be kept for a few years.
18      *
19      * @link    http://www.hardened-php.net/suhosin/
20      * @param    string    $function_name    Function to check for
21      * @return    bool    TRUE if the function exists and is safe to call,
22      *            FALSE otherwise.
23      */
24     function function_usable($function_name)
25     {
26         static $_suhosin_func_blacklist;
27 
28         if (function_exists($function_name))
29         {
30             if ( ! isset($_suhosin_func_blacklist))
31             {
32                 $_suhosin_func_blacklist = extension_loaded('suhosin')
33                     ? explode(',', trim(ini_get('suhosin.executor.func.blacklist')))
34                     : array();
35             }
36 
37             return ! in_array($function_name, $_suhosin_func_blacklist, TRUE);
38         }
39 
40         return FALSE;
41     }

View Code

　　函数功能类似于function_exist(),不过在外面包装了一层，还需要检查下函数是否在suhosin.executor.func.blacklist中（类似于黑名单？），如果在还是会返回false。

发表于 2018-05-03 16:40 Andrés 阅读(849) 评论(0) 编辑收藏举报

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php优秀框架codeigniter学习系列——common.php

is_php

is_really_writable

&load_class

&is_loaded($class = '')

&get_config(Array $replace = array())

View Code

config_item($item)

&get_mimes()

is_https()

is_cli()

show_error($message, $status_code = 500, $heading = 'An Error Was Encountered')

show_404($page = '', $log_error = TRUE)

log_message($level, $message)

set_status_header($code = 200, $text = '')

_error_handler($severity, $message, $filepath, $line)

_exception_handler($exception)

_shutdown_handler()

remove_invisible_characters($str, $url_encoded = TRUE)

html_escape($var, $double_encode = TRUE)

_stringify_attributes($attributes, $js = FALSE)

View Code

function_usable($function_name)

公告

remove_invisible_characters($str, $url_encoded = TRUE)　　