我想使用 PSR-0 标准的方式来自动加载类而不需要添加包含，例如如何用自动加载机制替换下面的代码：
namespace Example;
use MyLib\Controller;
include_once './library/MyLib/Controller/AbstractController.php';
class MyController extends Controller\AbstractController {
[...]
所以在上面的例子中，它表明在每个控制器中我都需要包含抽象控制器，这太疯狂了......
我在这里找到了 PSR-0 代码：
https://github.com/php-fig/fig-standards/blob/master/accepted/PSR-0.md
https://gist.github.com/221634
但我不知道如何在我的应用程序中实现它。
【问题讨论】：
您需要在应用程序的第一个脚本中包含（包含/要求语句）带有自动加载器代码的文件
如果你像@Skpd 所说的那样选择使用 Composer 的自动加载器，那么你应该在你的第一个 PHP 脚本的顶部有这样的代码。
include_once __DIR__ . '/composer_autoloader.php'
$loader = new \Composer\Autoload\ClassLoader();
$loader->add('MyLib', __DIR__.'/library/');
$loader->register();
如果您决定使用 Composer 作为您的供应商经理，请将您的自定义命名空间添加到您的 composer.json 并包括 vendor/autoload.php
【讨论】：
您需要使用自动加载器。有来自 Composer 的示例类加载器：
<?php
/*
* This file is part of Composer.
*
* (c) Nils Adermann <naderman@naderman.de>
* Jordi Boggiano <j.boggiano@seld.be>
*
* For the full copyright and license information, please view the LICENSE
* file that was distributed with this source code.
*/
namespace Composer\Autoload;
/**
* ClassLoader implements a PSR-0 class loader
*
* See https://github.com/php-fig/fig-standards/blob/master/accepted/PSR-0.md
*
* $loader = new \Composer\Autoload\ClassLoader();
*
* // register classes with namespaces
* $loader->add('Symfony\Component', __DIR__.'/component');
* $loader->add('Symfony', __DIR__.'/framework');
*
* // activate the autoloader
* $loader->register();
*
* // to enable searching the include path (eg. for PEAR packages)
* $loader->setUseIncludePath(true);
*
* In this example, if you try to use a class in the Symfony\Component
* namespace or one of its children (Symfony\Component\Console for instance),
* the autoloader will first look for the class under the component/
* directory, and it will then fallback to the framework/ directory if not
* found before giving up.
*
* This class is loosely based on the Symfony UniversalClassLoader.
*
* @author Fabien Potencier <fabien@symfony.com>
* @author Jordi Boggiano <j.boggiano@seld.be>
*/
class ClassLoader
{
private $prefixes = array();
private $fallbackDirs = array();
private $useIncludePath = false;
private $classMap = array();
public function getPrefixes()
{
return $this->prefixes;
}
public function getFallbackDirs()
{
return $this->fallbackDirs;
}
public function getClassMap()
{
return $this->classMap;
}
/**
* @param array $classMap Class to filename map
*/
public function addClassMap(array $classMap)
{
if ($this->classMap) {
$this->classMap = array_merge($this->classMap, $classMap);
} else {
$this->classMap = $classMap;
}
}
/**
* Registers a set of classes
*
* @param string $prefix The classes prefix
* @param array|string $paths The location(s) of the classes
*/
public function add($prefix, $paths)
{
if (!$prefix) {
foreach ((array) $paths as $path) {
$this->fallbackDirs[] = $path;
}
return;
}
if (isset($this->prefixes[$prefix])) {
$this->prefixes[$prefix] = array_merge(
$this->prefixes[$prefix],
(array) $paths
);
} else {
$this->prefixes[$prefix] = (array) $paths;
}
}
/**
* Turns on searching the include path for class files.
*
* @param bool $useIncludePath
*/
public function setUseIncludePath($useIncludePath)
{
$this->useIncludePath = $useIncludePath;
}
/**
* Can be used to check if the autoloader uses the include path to check
* for classes.
*
* @return bool
*/
public function getUseIncludePath()
{
return $this->useIncludePath;
}
/**
* Registers this instance as an autoloader.
*
* @param bool $prepend Whether to prepend the autoloader or not
*/
public function register($prepend = false)
{
spl_autoload_register(array($this, 'loadClass'), true, $prepend);
}
/**
* Unregisters this instance as an autoloader.
*/
public function unregister()
{
spl_autoload_unregister(array($this, 'loadClass'));
}
/**
* Loads the given class or interface.
*
* @param string $class The name of the class
* @return bool|null True, if loaded
*/
public function loadClass($class)
{
if ($file = $this->findFile($class)) {
include $file;
return true;
}
}
/**
* Finds the path to the file where the class is defined.
*
* @param string $class The name of the class
*
* @return string|null The path, if found
*/
public function findFile($class)
{
if ('\\' == $class[0]) {
$class = substr($class, 1);
}
if (isset($this->classMap[$class])) {
return $this->classMap[$class];
}
if (false !== $pos = strrpos($class, '\\')) {
// namespaced class name
$classPath = str_replace('\\', DIRECTORY_SEPARATOR, substr($class, 0, $pos)) . DIRECTORY_SEPARATOR;
$className = substr($class, $pos + 1);
} else {
// PEAR-like class name
$classPath = null;
$className = $class;
}
$classPath .= str_replace('_', DIRECTORY_SEPARATOR, $className) . '.php';
foreach ($this->prefixes as $prefix => $dirs) {
if (0 === strpos($class, $prefix)) {
foreach ($dirs as $dir) {
if (file_exists($dir . DIRECTORY_SEPARATOR . $classPath)) {
return $dir . DIRECTORY_SEPARATOR . $classPath;
}
}
}
}
foreach ($this->fallbackDirs as $dir) {
if (file_exists($dir . DIRECTORY_SEPARATOR . $classPath)) {
return $dir . DIRECTORY_SEPARATOR . $classPath;
}
}
if ($this->useIncludePath && $file = stream_resolve_include_path($classPath)) {
return $file;
}
return $this->classMap[$class] = false;
}
}
【讨论】：