thinkphp5源码剖析系列1-类的自动加载机制

Posted 2020-11-27 cl94

前言

tp5想必大家都不陌生，但是大部分人都停留在应用的层面，我将开启系列随笔，深入剖析tp5源码，以供大家顺利进阶。本章将从类的自动加载讲起，自动加载是tp框架的灵魂所在，也是成熟php框架的必备功能

入口

// [ 应用入口文件 ]
namespace think;

// 加载基础文件
require __DIR__ . ‘/../thinkphp/base.php‘;

base.php

<?php
// +----------------------------------------------------------------------
// | ThinkPHP [ WE CAN DO IT JUST THINK ]
// +----------------------------------------------------------------------
// | Copyright (c) 2006~2018 http://thinkphp.cn All rights reserved.
// +----------------------------------------------------------------------
// | Licensed ( http://www.apache.org/licenses/LICENSE-2.0 )
// +----------------------------------------------------------------------
// | Author: liu21st <[e-mail]>
// +----------------------------------------------------------------------
namespace think;

// 载入Loader类
require __DIR__ . ‘/library/think/Loader.php‘;

// 注册自动加载
Loader::register();

// 注册错误和异常处理机制
Error::register();

// 实现日志接口
if (interface_exists(‘PsrLogLoggerInterface‘)) {
    interface LoggerInterface extends PsrLogLoggerInterface
    {}
} else {
    interface LoggerInterface
    {}
}

/*
 * 使用 ClassName::class 可以获取一个字符串，包含了类 ClassName 的完全限定名称
 * 注册类库别名的作用：建立映射，访问 Db 即可映射到 	hinkDb
 * 它的存在可提升性能
 */
// 注册类库别名
Loader::addClassAlias([
    /**
     * 由于命名空间的机制，
     * 这里的 facade 相对命名空间地址会拼接此处的think命名空间，组合成为一个绝对的 	hinkfacade 命名空间
     */
    ‘App‘      => facadeApp::class, 
    ‘Build‘    => facadeBuild::class,
    ‘Cache‘    => facadeCache::class,
    ‘Config‘   => facadeConfig::class,
    ‘Cookie‘   => facadeCookie::class,
    ‘Db‘       => Db::class,
    ‘Debug‘    => facadeDebug::class,
    ‘Env‘      => facadeEnv::class,
    ‘Facade‘   => Facade::class,
    ‘Hook‘     => facadeHook::class,
    ‘Lang‘     => facadeLang::class,
    ‘Log‘      => facadeLog::class,
    ‘Request‘  => facadeRequest::class,
    ‘Response‘ => facadeResponse::class,
    ‘Route‘    => facadeRoute::class,
    ‘Session‘  => facadeSession::class,
    ‘Url‘      => facadeUrl::class,
    ‘Validate‘ => facadeValidate::class,
    ‘View‘     => facadeView::class,
]);

主角Loader.php

<?php
// +----------------------------------------------------------------------
// | ThinkPHP [ WE CAN DO IT JUST THINK ]
// +----------------------------------------------------------------------
// | Copyright (c) 2006~2018 http://thinkphp.cn All rights reserved.
// +----------------------------------------------------------------------
// | Licensed ( http://www.apache.org/licenses/LICENSE-2.0 )
// +----------------------------------------------------------------------
// | Author: liu21st <[e-mail]>
// +----------------------------------------------------------------------

namespace think;

use thinkexceptionClassNotFoundException;

class Loader
{
    /**
     * 类名映射信息
     * @var array
     */
    protected static $classMap = [];

    /**
     * 类库别名
     * @var array
     */
    protected static $classAlias = [];

    /**
     * PSR-4
     * @var array
     */
    private static $prefixLengthsPsr4 = [];
    private static $prefixDirsPsr4    = [];
    private static $fallbackDirsPsr4  = [];

    /**
     * PSR-0
     * @var array
     */
    private static $prefixesPsr0     = [];
    private static $fallbackDirsPsr0 = [];

    /**
     * 需要加载的文件
     * @var array
     */
    private static $files = [];

    /**
     * Composer安装路径
     * @var string
     */
    private static $composerPath;

    // 获取应用根目录
    public static function getRootPath()
    {
    
        /*
         * SAPI（Server Application Programming Interface）服务器应用程序编程接口，即PHP与其他应用交互的接口，
         * PHP脚本要执行有很多方式，通过Web服务器，或者直接在命令行下，也可以嵌入在其他程序中。
         * SAPI提供了一个和外部通信的接口，常见的SAPI有：cgi、fast-cgi、cli、apache模块的DLL、isapi
         * cli表示是命令行运行
         */
        if (‘cli‘ == PHP_SAPI) {
            $scriptName = realpath($_SERVER[‘argv‘][0]);
        } else {
            /*
             * $_SERVER[‘SCRIPT_FILENAME‘] : 当前执行程序的绝对路径及文件名(相对index.php入口文件)
             * $scriptName : D:/workspace/project/phpSite/tp5.1code/tp5/public/index.php
             */
            $scriptName = $_SERVER[‘SCRIPT_FILENAME‘];
        }
        /*
         * dirname() 函数返回路径中的目录名称部分。如果是文件，文件名出栈，如果是目录，目录出栈
         * realpath() 函数返回绝对路径。
         * 该函数删除所有符号连接（比如 ‘/./‘, ‘/../‘ 以及多余的 ‘/‘），返回绝对路径名。
         * $path : D:workspaceprojectphpSite	p5.1code	p5public
         */
        $path = realpath(dirname($scriptName));
        /*
         * DIRECTORY_SEPARATOR : 目录分隔符，是定义php的内置常量。兼容操作系统
         * 由于当前目录在public目录下
         * 判断public目录下是否有think文件，如果没有，则目录出栈转到根目录
         */
        if (!is_file($path . DIRECTORY_SEPARATOR . ‘think‘)) {
            $path = dirname($path);
        }
        return $path . DIRECTORY_SEPARATOR;
    }

    // 注册自动加载机制
    public static function register($autoload = ‘‘)
    {
        /*
        PHP碰到没有定义的类就执行think\Loader::autoload()

        spl_autoload_register有三个参数

        autoload_function
        欲注册的自动装载函数。如果没有提供任何参数，则自动注册 autoload 的默认实现函数spl_autoload()。

        throw
        此参数设置了 autoload_function 无法成功注册时， spl_autoload_register()是否抛出异常。

        prepend
        如果是 true，spl_autoload_register() 会添加函数到队列之首，而不是队列尾部。
        */
        // 注册系统自动加载
        spl_autoload_register($autoload ?: ‘think\Loader::autoload‘, true, true);

        $rootPath = self::getRootPath();
        // $rootPath ：D:workspaceprojectphpSite	p5.1code	p5
        self::$composerPath = $rootPath . ‘vendor‘ . DIRECTORY_SEPARATOR . ‘composer‘ . DIRECTORY_SEPARATOR;
        // self::$composerPath : D:workspaceprojectphpSite	p5.1code	p5vendorcomposer      
        // Composer自动加载支持
        if (is_dir(self::$composerPath)) {
            if (is_file(self::$composerPath . ‘autoload_static.php‘)) {
                require self::$composerPath . ‘autoload_static.php‘;
                // 返回当前所有类的集合
                $declaredClass = get_declared_classes();
                // 取出最后一个类，即刚刚引入的autoload_static.php中的类
                $composerClass = array_pop($declaredClass);

                foreach ([‘prefixLengthsPsr4‘, ‘prefixDirsPsr4‘, ‘fallbackDirsPsr4‘, ‘prefixesPsr0‘, ‘fallbackDirsPsr0‘, ‘classMap‘, ‘files‘] as $attr) {
                    // property_exists() ：检测对象或类是否存在该属性
                    if (property_exists($composerClass, $attr)) {
                        // 将它的 prefixLengthsPsr4 和 prefixDirsPsr4 属性挂载到本类
                        self::${$attr} = $composerClass::${$attr};
                    }
                }
            } else {
                self::registerComposerLoader(self::$composerPath);
            }
        }

        /*
         * __DIR__ ： 本文件所在目录(Loader.php文件)
         * 将 think 和 traits 也挂载到本类的 prefixLengthsPsr4 和 prefixDirsPsr4 属性上
         */ 
        // 注册命名空间定义
        self::addNamespace([
            ‘think‘  => __DIR__,
            ‘traits‘ => dirname(__DIR__) . DIRECTORY_SEPARATOR . ‘traits‘,
        ]);
      
        // 类的映射键值对，须手动生成才有这个文件
        // 加载类库映射文件
        if (is_file($rootPath . ‘runtime‘ . DIRECTORY_SEPARATOR . ‘classmap.php‘)) {
            self::addClassMap(__include_file($rootPath . ‘runtime‘ . DIRECTORY_SEPARATOR . ‘classmap.php‘));
        }

        // 自动加载extend目录
        self::addAutoLoadDir($rootPath . ‘extend‘);
        // var_dump(self::$prefixLengthsPsr4);
        // var_dump(self::$prefixDirsPsr4);
        // var_dump(self::$fallbackDirsPsr4);
        // var_dump(self::$classMap);
        /*
        array(3) {
            ["t"]=>
            array(4) {
                ["thinkworker"]=>
                int(13)
                ["thinkcomposer"]=>
                int(15)
                ["think"]=>
                int(6)
                ["traits"]=>
                int(7)
            }
            ["a"]=>
            array(1) {
                ["app"]=>
                int(4)
            }
            ["W"]=>
            array(1) {
                ["Workerman"]=>
                int(10)
            }
        }
        array(6) {
            ["thinkworker"]=>
            array(1) {
                [0]=>
                string(87) "D:workspaceprojectphpSite	p5.1code	p5vendorcomposer/../topthink/think-worker/src"
            }
            ["thinkcomposer"]=>
            array(1) {
                [0]=>
                string(90) "D:workspaceprojectphpSite	p5.1code	p5vendorcomposer/../topthink/think-installer/src"
            }
            ["app"]=>
            array(1) {
                [0]=>
                string(76) "D:workspaceprojectphpSite	p5.1code	p5vendorcomposer/../../application"
            }
            ["Workerman"]=>
            array(2) {
                [0]=>
                string(81) "D:workspaceprojectphpSite	p5.1code	p5vendorcomposer/../workerman/workerman"
                [1]=>
                string(89) "D:workspaceprojectphpSite	p5.1code	p5vendorcomposer/../workerman/workerman-for-win"
            }
            ["think"]=>
            array(1) {
                [0]=>
                string(65) "D:workspaceprojectphpSite	p5.1code	p5	hinkphplibrary	hink"
            }
            ["traits"]=>
            array(1) {
                [0]=>
                string(66) "D:workspaceprojectphpSite	p5.1code	p5	hinkphplibrary	raits"
            }
        }
        array(1) {
            [0]=>
            string(49) "D:workspaceprojectphpSite	p5.1code	p5extend"
        }
        array(0) {
        }
        
        */
    }

    // 自动加载
    public static function autoload($class)
    {
        // 如果之前配置过别名，注册别名
        if (isset(self::$classAlias[$class])) {
            return class_alias(self::$classAlias[$class], $class);
        }

        // 通过命名空间解析到文件名
        if ($file = self::findFile($class)) {

            // Win环境严格区分大小写
            if (strpos(PHP_OS, ‘WIN‘) !== false && pathinfo($file, PATHINFO_FILENAME) != pathinfo(realpath($file), PATHINFO_FILENAME)) {
                return false;
            }

            // echo $class.‘---‘.$file.‘<br />‘;
            __include_file($file);
            return true;
        }
    }

    /**
     * 查找文件
     * @access private
     * @param  string $class
     * @return string|false
     */
    private static function findFile($class)
    {
        if (!empty(self::$classMap[$class])) {
            // 类库映射
            return self::$classMap[$class];
        }

        /*
         * 利用 Psr4 的规则，执行匹配查询，如果匹配到，则返回文件名。
         * Psr4 的规则一般包含composer安装的类库的命名空间对应的目录，
         * 和app、以及框架底层 think、traits命名空间对应的目录
         */
        // 查找 PSR-4
        $logicalPathPsr4 = strtr($class, ‘\‘, DIRECTORY_SEPARATOR) . ‘.php‘;
        
        $first = $class[0];
        // var_dump($first );die;
        if (isset(self::$prefixLengthsPsr4[$first])) {
            foreach (self::$prefixLengthsPsr4[$first] as $prefix => $length) {
                if (0 === strpos($class, $prefix)) {
                    foreach (self::$prefixDirsPsr4[$prefix] as $dir) {
                        if (is_file($file = $dir . DIRECTORY_SEPARATOR . substr($logicalPathPsr4, $length))) {
                            return $file;
                        }
                    }
                }
            }
        }

        /**
         * 这里匹配 extend 下面的类目
         */
        // 查找 PSR-4 fallback dirs
        foreach (self::$fallbackDirsPsr4 as $dir) {
            if (is_file($file = $dir . DIRECTORY_SEPARATOR . $logicalPathPsr4)) {
                return $file;
            }
        }

        // 查找 PSR-0
        if (false !== $pos = strrpos($class, ‘\‘)) {
            // namespaced class name
            $logicalPathPsr0 = substr($logicalPathPsr4, 0, $pos + 1)
            . strtr(substr($logicalPathPsr4, $pos + 1), ‘_‘, DIRECTORY_SEPARATOR);
        } else {
            // PEAR-like class name
            $logicalPathPsr0 = strtr($class, ‘_‘, DIRECTORY_SEPARATOR) . ‘.php‘;
        }

        if (isset(self::$prefixesPsr0[$first])) {
            foreach (self::$prefixesPsr0[$first] as $prefix => $dirs) {
                if (0 === strpos($class, $prefix)) {
                    foreach ($dirs as $dir) {
                        if (is_file($file = $dir . DIRECTORY_SEPARATOR . $logicalPathPsr0)) {
                            return $file;
                        }
                    }
                }
            }
        }

        // 查找 PSR-0 fallback dirs
        foreach (self::$fallbackDirsPsr0 as $dir) {
            if (is_file($file = $dir . DIRECTORY_SEPARATOR . $logicalPathPsr0)) {
                return $file;
            }
        }

        return self::$classMap[$class] = false;
    }

    // 注册classmap
    public static function addClassMap($class, $map = ‘‘)
    {
        if (is_array($class)) {
            self::$classMap = array_merge(self::$classMap, $class);
        } else {
            self::$classMap[$class] = $map;
        }
    }

    // 注册命名空间
    public static function addNamespace($namespace, $path = ‘‘)
    {
        if (is_array($namespace)) {
            foreach ($namespace as $prefix => $paths) {
                self::addPsr4($prefix . ‘\‘, rtrim($paths, DIRECTORY_SEPARATOR), true);
            }
        } else {
            self::addPsr4($namespace . ‘\‘, rtrim($path, DIRECTORY_SEPARATOR), true);
        }
    }

    // 添加Ps0空间
    private static function addPsr0($prefix, $paths, $prepend = false)
    {
        if (!$prefix) {
            if ($prepend) {
                self::$fallbackDirsPsr0 = array_merge(
                    (array) $paths,
                    self::$fallbackDirsPsr0
                );
            } else {
                self::$fallbackDirsPsr0 = array_merge(
                    self::$fallbackDirsPsr0,
                    (array) $paths
                );
            }

            return;
        }

        $first = $prefix[0];
        if (!isset(self::$prefixesPsr0[$first][$prefix])) {
            self::$prefixesPsr0[$first][$prefix] = (array) $paths;

            return;
        }

        if ($prepend) {
            self::$prefixesPsr0[$first][$prefix] = array_merge(
                (array) $paths,
                self::$prefixesPsr0[$first][$prefix]
            );
        } else {
            self::$prefixesPsr0[$first][$prefix] = array_merge(
                self::$prefixesPsr0[$first][$prefix],
                (array) $paths
            );
        }
    }

    // 添加Psr4空间
    private static function addPsr4($prefix, $paths, $prepend = false)
    {
        if (!$prefix) {
            // Register directories for the root namespace.
            if ($prepend) {
                self::$fallbackDirsPsr4 = array_merge(
                    (array) $paths,
                    self::$fallbackDirsPsr4
                );
            } else {
                self::$fallbackDirsPsr4 = array_merge(
                    self::$fallbackDirsPsr4,
                    (array) $paths
                );
            }
        } elseif (!isset(self::$prefixDirsPsr4[$prefix])) {
            // Register directories for a new namespace.
            $length = strlen($prefix);
            if (‘\‘ !== $prefix[$length - 1]) {
                throw new InvalidArgumentException("A non-empty PSR-4 prefix must end with a namespace separator.");
            }

            self::$prefixLengthsPsr4[$prefix[0]][$prefix] = $length;
            self::$prefixDirsPsr4[$prefix]                = (array) $paths;
        } elseif ($prepend) {
            // Prepend directories for an already registered namespace.
            self::$prefixDirsPsr4[$prefix] = array_merge(
                (array) $paths,
                self::$prefixDirsPsr4[$prefix]
            );
        } else {
            // Append directories for an already registered namespace.
            self::$prefixDirsPsr4[$prefix] = array_merge(
                self::$prefixDirsPsr4[$prefix],
                (array) $paths
            );
        }
    }

    // 注册自动加载类库目录
    public static function addAutoLoadDir($path)
    {
        self::$fallbackDirsPsr4[] = $path;
    }

    // 注册类别名
    public static function addClassAlias($alias, $class = null)
    {
        
        if (is_array($alias)) {
            self::$classAlias = array_merge(self::$classAlias, $alias);
        } else {
            self::$classAlias[$alias] = $class;
        }
    }

    // 注册composer自动加载
    public static function registerComposerLoader($composerPath)
    {
        if (is_file($composerPath . ‘autoload_namespaces.php‘)) {
            $map = require $composerPath . ‘autoload_namespaces.php‘;
            foreach ($map as $namespace => $path) {
                self::addPsr0($namespace, $path);
            }
        }

        if (is_file($composerPath . ‘autoload_psr4.php‘)) {
            $map = require $composerPath . ‘autoload_psr4.php‘;
            foreach ($map as $namespace => $path) {
                self::addPsr4($namespace, $path);
            }
        }

        if (is_file($composerPath . ‘autoload_classmap.php‘)) {
            $classMap = require $composerPath . ‘autoload_classmap.php‘;
            if ($classMap) {
                self::addClassMap($classMap);
            }
        }

        if (is_file($composerPath . ‘autoload_files.php‘)) {
            self::$files = require $composerPath . ‘autoload_files.php‘;
        }
    }

    // 加载composer autofile文件
    public static function loadComposerAutoloadFiles()
    {
        foreach (self::$files as $fileIdentifier => $file) {
            if (empty($GLOBALS[‘__composer_autoload_files‘][$fileIdentifier])) {
                __require_file($file);

                $GLOBALS[‘__composer_autoload_files‘][$fileIdentifier] = true;
            }
        }
    }

    /**
     * 字符串命名风格转换
     * type 0 将Java风格转换为C的风格 1 将C风格转换为Java的风格
     * @access public
     * @param  string  $name 字符串
     * @param  integer $type 转换类型
     * @param  bool    $ucfirst 首字母是否大写（驼峰规则）
     * @return string
     */
    public static function parseName($name, $type = 0, $ucfirst = true)
    {
        if ($type) {
            $name = preg_replace_callback(‘/_([a-zA-Z])/‘, function ($match) {
                return strtoupper($match[1]);
            }, $name);
            return $ucfirst ? ucfirst($name) : lcfirst($name);
        }

        return strtolower(trim(preg_replace("/[A-Z]/", "_\0", $name), "_"));
    }

    /**
     * 创建工厂对象实例
     * @access public
     * @param  string $name         工厂类名
     * @param  string $namespace    默认命名空间
     * @return mixed
     */
    public static function factory($name, $namespace = ‘‘, ...$args)
    {
        $class = false !== strpos($name, ‘\‘) ? $name : $namespace . ucwords($name);

        if (class_exists($class)) {
            return Container::getInstance()->invokeClass($class, $args);
        } else {
            throw new ClassNotFoundException(‘class not exists:‘ . $class, $class);
        }
    }
}

/**
 * 作用范围隔离
 *
 * @param $file
 * @return mixed
 */
function __include_file($file)
{
    return include $file;
}

function __require_file($file)
{
    return require $file;
}

autoload_static.php

<?php

// autoload_static.php @generated by Composer

namespace ComposerAutoload;

class ComposerStaticInita1e68a2034863afda74e609f9cf189d1
{
    public static $prefixLengthsPsr4 = array (
        ‘t‘ => 
        array (
            ‘think\worker\‘ => 13,
            ‘think\composer\‘ => 15,
        ),
        ‘a‘ => 
        array (
            ‘app\‘ => 4,
        ),
        ‘W‘ => 
        array (
            ‘Workerman\‘ => 10,
        ),
    );

    public static $prefixDirsPsr4 = array (
        ‘think\worker\‘ => 
        array (
            0 => __DIR__ . ‘/..‘ . ‘/topthink/think-worker/src‘,
        ),
        ‘think\composer\‘ => 
        array (
            0 => __DIR__ . ‘/..‘ . ‘/topthink/think-installer/src‘,
        ),
        ‘app\‘ => 
        array (
            0 => __DIR__ . ‘/../..‘ . ‘/application‘,
        ),
        ‘Workerman\‘ => 
        array (
            0 => __DIR__ . ‘/..‘ . ‘/workerman/workerman‘,
            1 => __DIR__ . ‘/..‘ . ‘/workerman/workerman-for-win‘,
        ),
    );

    public static function getInitializer(ClassLoader $loader)
    {
        return Closure::bind(function () use ($loader) {
            $loader->prefixLengthsPsr4 = ComposerStaticInita1e68a2034863afda74e609f9cf189d1::$prefixLengthsPsr4;
            $loader->prefixDirsPsr4 = ComposerStaticInita1e68a2034863afda74e609f9cf189d1::$prefixDirsPsr4;

        }, null, ClassLoader::class);
    }
}

总结：类的自动加载，其实就是先绑定了自动加载函数，然后在类的属性上面定义了一系列的映射关系，然后在自动加载函数中通过命名空间/类名参数查询映射关系，将映射的目录include引入的操作