PHP Composer自动加载使用实战

目录

• 一、没有 composer 时 PHP 是怎么做的
• __autoload 自动加载器
• 使用 spl_autoload_register 注册多个自动加载器
• 二、PSR 规范
• 三、Composer 自动加载的过程
• 第一步，建立类的命名空间和类存放位置的映射关系
• 第二步，如何找到类并加载
• 第三步，如何加载全局函数

// we've writen this code where we need
function __autoload($classname) {
    $filename = "./". $classname .".php";
    include_once($filename);
}
// we've called a class ***
$obj = new myClass();

function my_autoloader($class) {
    var_dump("my_autoloader", $class);
}
spl_autoload_register('my_autoloader');
// 静态方法
class MyClass1 {
    public static function autoload($className) {
        var_dump("MyClass1 autoload", $className);
    }
}
spl_autoload_register(array('MyClass1', 'autoload'));
// 非静态方法
class MyClass2 {
    public function autoload($className) {
        var_dump("MyClass2 autoload", $className);
    }
}
$instance = new MyClass2();
spl_autoload_register(array($instance, 'autoload'));
new \NotDefineClassName();
/*
输出
string(32) "my_autoloader NotDefineClassName"
string(36) "MyClass1 autoload NotDefineClassName"
string(36) "MyClass2 autoload NotDefineClassName"
*/

// autoload.php @generated by Composer
// vendor/autoload.php
require_once __DIR__ . '/composer/autoload_real.php';
// 返回了autoload_real文件中的类方法
return ComposerAutoloaderInit7e421c277f7e8f810a19524f0d771cdb::getLoader();
/* ------------- */
// vendor/composer/autoload_real.php
public static function getLoader()
{
    if (null !== self::$loader) {
        return self::$loader;
    }
    // P0 初始化ClassLoader
    spl_autoload_register(array('ComposerAutoloaderInit7e421c277f7e8f810a19524f0d771cdb', 'loadClassLoader'), true, true);
    self::$loader = $loader = new \Composer\Autoload\ClassLoader();
    spl_autoload_unregister(array('ComposerAutoloaderInit7e421c277f7e8f810a19524f0d771cdb', 'loadClassLoader'));
    $useStaticLoader = PHP_VERSION_ID >= 50600 && !defined('HHVM_VERSION') && (!function_exists('zend_loader_file_encoded') || !zend_loader_file_encoded());
    if ($useStaticLoader) {
        require_once __DIR__ . '/autoload_static.php';
        // P1 向ClassLoader中set命名空间和文件路径映射关系
        call_user_func(\Composer\Autoload\ComposerStaticInit7e421c277f7e8f810a19524f0d771cdb::getInitializer($loader));
    } else {
        $map = require __DIR__ . '/autoload_namespaces.php';
        foreach ($map as $namespace => $path) {
            $loader->set($namespace, $path);
        }
        $map = require __DIR__ . '/autoload_psr4.php';
        foreach ($map as $namespace => $path) {
            $loader->setPsr4($namespace, $path);
        }
        $classMap = require __DIR__ . '/autoload_classmap.php';
        if ($classMap) {
            $loader->addClassMap($classMap);
        }
    }
    // P2 将ClassLoader中的loadClass方法，注册为加载器
    $loader->register(true);
    if ($useStaticLoader) {
        $includeFiles = Composer\Autoload\ComposerStaticInit7e421c277f7e8f810a19524f0d771cdb::$files;
    } else {
        $includeFiles = require __DIR__ . '/autoload_files.php';
    }
    foreach ($includeFiles as $fileIdentifier => $file) {
        composerRequire7e421c277f7e8f810a19524f0d771cdb($fileIdentifier, $file);
    }
    return $loader;
}

public static $prefixLengthsPsr4 = array (
    'p' => 
    array (
        'phpDocumentor\\Reflection\\' => 25,
    ),
    'W' => 
    array (
        'Webmozart\\Assert\\' => 17,
    ),
    'S' => 
    array (
        'Symfony\\Polyfill\\Ctype\\' => 23,
    ),
    'R' => 
    array (
        'RefactoringGuru\\' => 16,
    ),
    'P' => 
    array (
        'Prophecy\\' => 9,
    ),
    'D' => 
    array (
        'Doctrine\\Instantiator\\' => 22,
        'DeepCopy\\' => 9,
    ),
);
public static $prefixDirsPsr4 = array (
    'phpDocumentor\\Reflection\\' => 
    array (
        0 => __DIR__ . '/..' . '/phpdocumentor/reflection-common/src',
        1 => __DIR__ . '/..' . '/phpdocumentor/reflection-docblock/src',
        2 => __DIR__ . '/..' . '/phpdocumentor/type-resolver/src',
    ),
    'Webmozart\\Assert\\' => 
    array (
        0 => __DIR__ . '/..' . '/webmozart/assert/src',
    ),
    'Symfony\\Polyfill\\Ctype\\' => 
    array (
        0 => __DIR__ . '/..' . '/symfony/polyfill-ctype',
    ),
    'RefactoringGuru\\' => 
    array (
        0 => __DIR__ . '/../..' . '/',
    ),
    'Prophecy\\' => 
    array (
        0 => __DIR__ . '/..' . '/phpspec/prophecy/src/Prophecy',
    ),
    'Doctrine\\Instantiator\\' => 
    array (
        0 => __DIR__ . '/..' . '/doctrine/instantiator/src/Doctrine/Instantiator',
    ),
    'DeepCopy\\' => 
    array (
        0 => __DIR__ . '/..' . '/myclabs/deep-copy/src/DeepCopy',
    ),
);
public static $classMap = array (
        'File_Iterator' => __DIR__ . '/..' . '/phpunit/php-file-iterator/src/Iterator.php',
        'File_Iterator_Facade' => __DIR__ . '/..' . '/phpunit/php-file-iterator/src/Facade.php',
        'File_Iterator_Factory' => __DIR__ . '/..' . '/phpunit/php-file-iterator/src/Factory.php',
        'PHPUnit\\Exception' => __DIR__ . '/..' . '/phpunit/phpunit/src/Exception.php',
    ...
);

public function loadClass($class)
{
    if ($file = $this->findFile($class)) {
        includeFile($file);
        return true;
    }
}
function includeFile($file)
{
    include $file;
}

public function findFile($class)
{
    // class map lookup
    if (isset($this->classMap[$class])) {
        return $this->classMap[$class];
    }
    if ($this->classMapAuthoritative || isset($this->missingClasses[$class])) {
        return false;
    }
    if (null !== $this->apcuPrefix) {
        $file = apcu_fetch($this->apcuPrefix.$class, $hit);
        if ($hit) {
            return $file;
        }
    }
    $file = $this->findFileWithExtension($class, '.php');
    // Search for Hack files if we are running on HHVM
    if (false === $file && defined('HHVM_VERSION')) {
        $file = $this->findFileWithExtension($class, '.hh');
    }
    if (null !== $this->apcuPrefix) {
        apcu_add($this->apcuPrefix.$class, $file);
    }
    if (false === $file) {
        // Remember that this class does not exist.
        $this->missingClasses[$class] = true;
    }
    return $file;
}

if ($useStaticLoader) {
    $includeFiles = Composer\Autoload\ComposerStaticInit7e421c277f7e8f810a19524f0d771cdb::$files;
} else {
    $includeFiles = require __DIR__ . '/autoload_files.php';
}
foreach ($includeFiles as $fileIdentifier => $file) {
    composerRequire7e421c277f7e8f810a19524f0d771cdb($fileIdentifier, $file);
}
return $loader;

// autoload_static.php
public static $files = array (
    '320cde22f66dd4f5d3fd621d3e88b98f' => __DIR__ . '/..' . '/symfony/polyfill-ctype/bootstrap.php',
    '6124b4c8570aa390c21fafd04a26c69f' => __DIR__ . '/..' . '/myclabs/deep-copy/src/DeepCopy/deep_copy.php',
);
// vendor/symfony/polyfill-ctype/bootstrap.php
if (!function_exists('ctype_alnum')) {
    function ctype_alnum($text) { return p\Ctype::ctype_alnum($text); }
}
if (!function_exists('ctype_alpha')) {
    function ctype_alpha($text) { return p\Ctype::ctype_alpha($text); }
}