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通过分析WP的代码来学习PHP。1
下载了WP的代码，并且应用到了网站上面，现在也在正常的运行中，地址是：www.freealgorithm.tk 。具体的申请过程就不赘述了，学习WP的代码。
他的目录结构就不看了，可以下载同名文件我会通过相对目录来区分。
进入网站的第一个默认的页面：/index.php
<?php/** * Front to the WordPress application. This file doesn‘t do anything, but loads * wp-blog-header.php which does and tells WordPress to load the theme. * * @package WordPress *//** * Tells WordPress to load the WordPress theme and output it. * * @var bool */define(‘WP_USE_THEMES‘, true);/** Loads the WordPress Environment and Template */ #定义WP_USE_THEMES为truerequire( dirname( __FILE__ ) . ‘/wp-blog-header.php‘ ); #返回路径中目录部分并且连接字符串得到此php文件的位置，用这个文件代替这个位置#引入同目录下的wp-blog-header.php文件
知识点：define函数，bool define ( string $name , mixed $value [, bool $case_insensitive = false ] ) 成功返回true否则false。
name：常量的名字。value：常量的值；仅允许标量和 null。标量的类型是 integer，float，string 或者 boolean。 也能够定义常量值的类型为 resource ，但并不推荐这么做，可能会导致未知状况的发生。
require函数替换参数指向的文件，__FILE__取得当前文件的绝对路径，dirname返回路径中的目录部分。比如这个文件返回的就是根目录/。‘.‘这个符号是字符串连接运算符，将dirname(__FILE__)返回的字符串与‘/wp-blog-header.php‘相连接然后require进去。
而/wp-blog-header.php这个文件被包含了，如下：
1 <?php 2 3 /** 4 * Loads the WordPress environment and template. 5 载入WordPress的环境和模板* 6 * @package WordPress 7 */ 8 9 10 if ( !isset($wp_did_header) ) #变量是否定义，定义返回true11 {12 13 $wp_did_header = true;14 15 16 require_once( dirname(__FILE__) . ‘/wp-load.php‘ );17 18 #用wp-load.php代替此语句19 /*如果定义了就不继续执行，否则执行下面的语句 */20 21 wp();22 23 24 require_once( ABSPATH . WPINC . ‘/template-loader.php‘ );25 26 #同样用27 }
isset函数用来判断这个变量是否已经被定义了，如果定义了就返回true否则返回false。如果没有定义的话就执行下面的语句，$wp_did_header=true;是定义变量，他是一个布尔变量。然后require_once这个文件 ,require_once函数与require的区别是以后再这个文件里不能再包含这个文件了，即仅仅包含这个文件一次。这些的动作是定义一个布尔变量且包含一个文件。下面的wp();函数指行，现在不知道这个函数的作用，一会就会看到。然后继续包含ABSPATH.WPINC.‘/template-loader.php‘。这个文件了。ABSPATH是绝对路径的意思，这个是WP自定义的常量，还有WPINC这两个，现在我们也不知道它的值是什么。此文件到此没有结束，我们继续跟踪进入wp-load.php.
1 <?php 2 3 /** 4 5 * Bootstrap file for setting the ABSPATH constant 6 * and loading the wp-config.php file. The wp-config.php 7 * file will then load the wp-settings.php file, which 8 * will then set up the WordPress environment. 9 *10 * If the wp-config.php file is not found then an error11 * will be displayed asking the visitor to set up the12 * wp-config.php file.13 *14 * Will also search for wp-config.php in WordPress‘ parent15 * directory to allow the WordPress directory to remain16 * untouched.17 *18 * @internal This file must be parsable by PHP4.19 *20 * @package WordPress21 */22 23 24 /** Define ABSPATH as this file‘s directory 25 */26 27 define( ‘ABSPATH‘, dirname(__FILE__) . ‘/‘ );28 29 30 error_reporting( E_CORE_ERROR | E_CORE_WARNING | E_COMPILE_ERROR | E_ERROR | E_WARNING | E_PARSE | E_USER_ERROR | E_USER_WARNING | E_RECOVERABLE_ERROR );31 32 /*error_reporting() 函数能够在运行时设置 error_reporting 指令。 PHP 有诸多错误级别，使用该函数可以设置在脚本运行时的级别。 如果没有设置可选参数 level， error_reporting() 仅会返回当前的错误报告级别。 */33 34 if ( file_exists( ABSPATH . ‘wp-config.php‘) ) #file_exists — 检查文件或目录是否存在，绝对路径+‘wp-config.php‘检测是否存在，这个文件是设置文件，后来在网站文件上传完成后进行安装时候来创建，所以在没有安装时候是不存在这个文件的。35 {36 37 /** The config file resides in ABSPATH */38 39 require_once( ABSPATH . ‘wp-config.php‘ );40 41 #如果文件存在，require_once把文件拿来42 #如果文件不存在，判断绝对路径取43 44 } elseif ( file_exists( dirname(ABSPATH) . ‘/wp-config.php‘ ) && ! file_exists( dirname(ABSPATH) . ‘/wp-settings.php‘ ) ) 45 {46 47 /** The config file resides one level above ABSPATH but is not part of another install */48 49 require_once( dirname(ABSPATH) . ‘/wp-config.php‘ );50 51 52 } else {53 54 // A config file doesn‘t exist55 56 57 define( ‘WPINC‘, ‘wp-includes‘ );58 59 define( ‘WP_CONTENT_DIR‘, ABSPATH . ‘wp-content‘ );60 61 require_once( ABSPATH . WPINC . ‘/load.php‘ );62 63 require_once( ABSPATH . WPINC . ‘/version.php‘ );64 65 66 wp_check_php_mysql_versions();67 68 wp_load_translations_early();69 70 // Standardize $_SERVER variables across setups.71 72 wp_fix_server_vars();73 74 75 require_once( ABSPATH . WPINC . ‘/functions.php‘ );76 77 78 $path = wp_guess_url() . ‘/wp-admin/setup-config.php‘;79 80 // Die with an error message81 82 $die = __( "There doesn‘t seem to be a <code>wp-config.php</code> file. I need this before we can get started." ) . ‘</p>‘;83 84 $die .= ‘<p>‘ . __( "Need more help? <a href=http://www.mamicode.com/‘http://codex.wordpress.org/Editing_wp-config.php‘>We got it." ) . ‘</p>‘;85 86 $die .= ‘<p>‘ . __( "You can create a <code>wp-config.php</code> file through a web interface, but this doesn‘t work for all server setups. The safest way is to manually create the file." ) . ‘</p>‘;87 $die .= ‘<p><a href="http://www.mamicode.com/‘ . $path . ‘" class="button button-large">‘ . __( "Create a Configuration File" ) . ‘</a>‘;88 89 90 wp_die( $die, __( ‘WordPress › Error‘ ) );91 }
代码稍长，但是以后的代码会更长。这里看到了他的注释说定义ABSPATH为当前文件的目录，而且看到了这个define语句，知道了ABSPATH是dirname(__FILE__).‘/‘。其实还是这个根目录。error_reporting函数的说明在代码里面注释着意思是定义错误级别，我在书中也没有看到类似的说明这个函数，现在不予理会。
if当前绝对路径下的 /wp-config.php文件存在的话就require这个文件。不存在的话继续判断（/wp-config.php和/wp-settings.php）文件是否不存在，那么判断wp-config.php这个文件的判断是否多余？wp-setting.php这个文件是存在的，而wp-config.php是后来在安装时后生成的，第一次安装使用时候是没有的。否则就定义WPINC为‘wp-includes‘，define( ‘WP_CONTENT_DIR‘, ABSPATH . ‘wp-content‘ );require_once( ABSPATH . WPINC . ‘/load.php‘ );这句是将 /wp-includes/load.php包含进去，require_once( ABSPATH . WPINC . ‘/version.php‘ );这句将/wp-includes/version.php包含进去。先跟踪进去/wp-includes/load.php。
1 <?php 2 3 /** 4 * These functions are needed to load WordPress. 5 * 6 * @internal This file must be parsable by PHP4. 7 * 8 * @package WordPress 9 */ 10 11 12 /** 13 * Turn register globals off. 14 * 15 * @access private 16 * @since 2.1.0 17 * @return null Will return null if register_globals PHP directive was disabled 18 */ 19 20 function wp_unregister_GLOBALS() 21 { 22 23 if ( !ini_get( ‘register_globals‘ ) ) 24 25 return; 26 27 28 if ( isset( $_REQUEST[‘GLOBALS‘] ) ) 29 30 die( ‘GLOBALS overwrite attempt detected‘ ); 31 32 // Variables that shouldn‘t be unset 33 34 $no_unset = array( ‘GLOBALS‘, ‘_GET‘, ‘_POST‘, ‘_COOKIE‘, ‘_REQUEST‘, ‘_SERVER‘, ‘_ENV‘, ‘_FILES‘, ‘table_prefix‘ ); 35 36 37 $input = array_merge( $_GET, $_POST, $_COOKIE, $_SERVER, $_ENV, $_FILES, isset( $_SESSION ) && is_array( $_SESSION ) ? $_SESSION : array() ); 38 foreach ( $input as $k => $v ) 39 40 if ( !in_array( $k, $no_unset ) && isset( $GLOBALS[$k] ) ) 41 { 42 43 unset( $GLOBALS[$k] ); 44 45 } 46 47 } 48 49 50 /** 51 * Fix $_SERVER variables for various setups. 52 * 53 * @access private 54 * @since 3.0.0 55 */ 56 57 function wp_fix_server_vars() 58 { 59 60 global $PHP_SELF; 61 62 63 $default_server_values = array( 64 65 ‘SERVER_SOFTWARE‘ => ‘‘, 66 67 ‘REQUEST_URI‘ => ‘‘, 68 69 ); 70 71 72 $_SERVER = array_merge( $default_server_values, $_SERVER ); 73 74 // Fix for IIS when running with PHP ISAPI 75 76 if ( empty( $_SERVER[‘REQUEST_URI‘] ) || ( php_sapi_name() != ‘cgi-fcgi‘ && preg_match( ‘/^Microsoft-IIS\//‘, $_SERVER[‘SERVER_SOFTWARE‘] ) ) ) 77 { 78 79 // IIS Mod-Rewrite 80 81 if ( isset( $_SERVER[‘HTTP_X_ORIGINAL_URL‘] ) ) 82 { 83 84 $_SERVER[‘REQUEST_URI‘] = $_SERVER[‘HTTP_X_ORIGINAL_URL‘]; 85 86 } 87 // IIS Isapi_Rewrite 88 89 else if ( isset( $_SERVER[‘HTTP_X_REWRITE_URL‘] ) ) { 90 91 $_SERVER[‘REQUEST_URI‘] = $_SERVER[‘HTTP_X_REWRITE_URL‘]; 92 93 } else { 94 // Use ORIG_PATH_INFO if there is no PATH_INFO 95 96 if ( !isset( $_SERVER[‘PATH_INFO‘] ) && isset( $_SERVER[‘ORIG_PATH_INFO‘] ) ) 97 98 $_SERVER[‘PATH_INFO‘] = $_SERVER[‘ORIG_PATH_INFO‘]; 99 100 101 // Some IIS + PHP configurations puts the script-name in the path-info (No need to append it twice)102 103 if ( isset( $_SERVER[‘PATH_INFO‘] ) ) {104 105 if ( $_SERVER[‘PATH_INFO‘] == $_SERVER[‘SCRIPT_NAME‘] )106 107 $_SERVER[‘REQUEST_URI‘] = $_SERVER[‘PATH_INFO‘];108 109 else110 111 $_SERVER[‘REQUEST_URI‘] = $_SERVER[‘SCRIPT_NAME‘] . $_SERVER[‘PATH_INFO‘];112 } 113 114 115 // Append the query string if it exists and isn‘t null116 117 if ( ! empty( $_SERVER[‘QUERY_STRING‘] ) ) {118 119 $_SERVER[‘REQUEST_URI‘] .= ‘?‘ . $_SERVER[‘QUERY_STRING‘];120 121 }122 123 }124 125 }126 127 128 // Fix for PHP as CGI hosts that set SCRIPT_FILENAME to something ending in php.cgi for all requests129 130 if ( isset( $_SERVER[‘SCRIPT_FILENAME‘] ) && ( strpos( $_SERVER[‘SCRIPT_FILENAME‘], ‘php.cgi‘ ) == strlen( $_SERVER[‘SCRIPT_FILENAME‘] ) - 7 ) )131 132 $_SERVER[‘SCRIPT_FILENAME‘] = $_SERVER[‘PATH_TRANSLATED‘];133 134 // Fix for Dreamhost and other PHP as CGI hosts135 136 if ( strpos( $_SERVER[‘SCRIPT_NAME‘], ‘php.cgi‘ ) !== false )137 138 unset( $_SERVER[‘PATH_INFO‘] );139 140 // Fix empty PHP_SELF141 142 $PHP_SELF = $_SERVER[‘PHP_SELF‘];143 144 if ( empty( $PHP_SELF ) )145 146 $_SERVER[‘PHP_SELF‘] = $PHP_SELF = preg_replace( ‘/(\?.*)?$/‘, ‘‘, $_SERVER["REQUEST_URI"] );147 148 }149 150 151 /**152 * Check for the required PHP version, and the MySQL extension or a database drop-in.153 *154 * Dies if requirements are not met.155 *156 * @access private157 * @since 3.0.0158 */159 160 161 function wp_check_php_mysql_versions() {162 163 global $required_php_version, $wp_version;164 165 $php_version = phpversion();166 167 if ( version_compare( $required_php_version, $php_version, ‘>‘ ) ) {168 169 wp_load_translations_early();170 171 header( ‘Content-Type: text/html; charset=utf-8‘ );172 173 die( sprintf( __( ‘Your server is running PHP version %1$s but WordPress %2$s requires at least %3$s.‘ ), $php_version, $wp_version, $required_php_version ) );174 175 }176 177 178 if ( ! extension_loaded( ‘mysql‘ ) && ! extension_loaded( ‘mysqli‘ ) && ! file_exists( WP_CONTENT_DIR . ‘/db.php‘ ) ) {179 180 wp_load_translations_early();181 182 header( ‘Content-Type: text/html; charset=utf-8‘ );183 184 die( __( ‘Your PHP installation appears to be missing the MySQL extension which is required by WordPress.‘ ) );185 186 }187 188 }189 190 191 192 /**193 * Don‘t load all of WordPress when handling a favicon.ico request.194 * Instead, send the headers for a zero-length favicon and bail.195 *196 * @since 3.0.0197 */198 199 200 function wp_favicon_request() {201 202 if ( ‘/favicon.ico‘ == $_SERVER[‘REQUEST_URI‘] ) {203 204 header(‘Content-Type: image/vnd.microsoft.icon‘);205 206 header(‘Content-Length: 0‘);207 208 exit;209 210 }211 212 }213 214 215 /**216 * Dies with a maintenance message when conditions are met.217 *218 * Checks for a file in the WordPress root directory named ".maintenance".219 * This file will contain the variable $upgrading, set to the time the file220 * was created. If the file was created less than 10 minutes ago, WordPress221 * enters maintenance mode and displays a message.222 *223 * The default message can be replaced by using a drop-in (maintenance.php in224 * the wp-content directory).225 *226 * @access private227 * @since 3.0.0228 */229 230 231 function wp_maintenance() {232 233 if ( !file_exists( ABSPATH . ‘.maintenance‘ ) || defined( ‘WP_INSTALLING‘ ) )234 235 return;236 237 238 global $upgrading;239 240 241 include( ABSPATH . ‘.maintenance‘ );242 243 // If the $upgrading timestamp is older than 10 minutes, don‘t die.244 245 if ( ( time() - $upgrading ) >= 600 )246 247 return;248 249 250 if ( file_exists( WP_CONTENT_DIR . ‘/maintenance.php‘ ) ) {251 252 require_once( WP_CONTENT_DIR . ‘/maintenance.php‘ );253 254 die();255 256 }257 258 259 wp_load_translations_early();260 261 262 $protocol = $_SERVER["SERVER_PROTOCOL"];263 264 if ( ‘HTTP/1.1‘ != $protocol && ‘HTTP/1.0‘ != $protocol )265 266 $protocol = ‘HTTP/1.0‘;267 268 header( "$protocol 503 Service Unavailable", true, 503 );269 270 header( ‘Content-Type: text/html; charset=utf-8‘ );271 272 header( ‘Retry-After: 600‘ );273 274 ?>
这是load.php的php部分，下面就基本是html代码了，html先不予分析。ini_get返回配制选项的值
通过分析WP的代码来学习PHP。1
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