PHP自动加载规范 PSR-0 和 PSR-4
1.PSR-0说明
- 一个标准的 命名空间(namespace) 与 类(class) 名称的定义必须符合以下结构:
\<Vendor Name>\(<Namespace>\)*<Class Name>
; - 其中
Vendor Name
为每个命名空间都必须要有的一个顶级命名空间名; - 需要的话,每个命名空间下可以拥有多个子命名空间;
- 当根据完整的命名空间名从文件系统中载入类文件时,每个命名空间之间的分隔符都会被转换成文件夹路径分隔符;
- 类名称中的每个
_
字符也会被转换成文件夹路径分隔符,而命名空间中的_
字符则是无特殊含义的。 - 当从文件系统中载入标准的命名空间或类时,都将添加
.php
为目标文件后缀; 组织名称(Vendor Name)
、命名空间(Namespace)
以及类的名称(Class Name)
可由任意大小写字母组成。
2.PSR-0范例
\Doctrine\Common\IsolatedClassLoader
=>/path/to/project/lib/vendor/Doctrine/Common/IsolatedClassLoader.php
\Symfony\Core\Request
=>/path/to/project/lib/vendor/Symfony/Core/Request.php
\namespace\package\Class_Name
=>/path/to/project/lib/vendor/namespace/package/Class/Name.php
\namespace\package_name\Class_Name
=>/path/to/project/lib/vendor/namespace/package_name/Class/Name.php
3.PSR-0自动加载类
<?php /* * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. * * This software consists of voluntary contributions made by many individuals * and is licensed under the MIT license. For more information, see * <http://www.doctrine-project.org>. */ /** * SplClassLoader implementation that implements the technical interoperability * standards for PHP 5.3 namespaces and class names. * * http://groups.google.com/group/php-standards/web/psr-0-final-proposal?pli=1 * * // Example which loads classes for the Doctrine Common package in the * // Doctrine\Common namespace. * $classLoader = new SplClassLoader('Doctrine\Common', '/path/to/doctrine'); * $classLoader->register(); * * @license http://www.opensource.org/licenses/mit-license.html MIT License * @author Jonathan H. Wage <jonwage@gmail.com> * @author Roman S. Borschel <roman@code-factory.org> * @author Matthew Weier O'Phinney <matthew@zend.com> * @author Kris Wallsmith <kris.wallsmith@gmail.com> * @author Fabien Potencier <fabien.potencier@symfony-project.org> */ class SplClassLoader { private $_fileExtension = '.php'; private $_namespace; private $_includePath; private $_namespaceSeparator = '\\'; /** * Creates a new <tt>SplClassLoader</tt> that loads classes of the * specified namespace. * * @param string $ns The namespace to use. */ public function __construct($ns = null, $includePath = null) { $this->_namespace = $ns; $this->_includePath = $includePath; } /** * Sets the namespace separator used by classes in the namespace of this class loader. * * @param string $sep The separator to use. */ public function setNamespaceSeparator($sep) { $this->_namespaceSeparator = $sep; } /** * Gets the namespace seperator used by classes in the namespace of this class loader. * * @return void */ public function getNamespaceSeparator() { return $this->_namespaceSeparator; } /** * Sets the base include path for all class files in the namespace of this class loader. * * @param string $includePath */ public function setIncludePath($includePath) { $this->_includePath = $includePath; } /** * Gets the base include path for all class files in the namespace of this class loader. * * @return string $includePath */ public function getIncludePath() { return $this->_includePath; } /** * Sets the file extension of class files in the namespace of this class loader. * * @param string $fileExtension */ public function setFileExtension($fileExtension) { $this->_fileExtension = $fileExtension; } /** * Gets the file extension of class files in the namespace of this class loader. * * @return string $fileExtension */ public function getFileExtension() { return $this->_fileExtension; } /** * Installs this class loader on the SPL autoload stack. */ public function register() { spl_autoload_register(array($this, 'loadClass')); } /** * Uninstalls this class loader from the SPL autoloader stack. */ public function unregister() { spl_autoload_unregister(array($this, 'loadClass')); } /** * Loads the given class or interface. * * @param string $className The name of the class to load. * @return void */ public function loadClass($className) { if (null === $this->_namespace || $this->_namespace.$this->_namespaceSeparator === substr($className, 0, strlen($this->_namespace.$this->_namespaceSeparator))) { $fileName = ''; $namespace = ''; if (false !== ($lastNsPos = strripos($className, $this->_namespaceSeparator))) { $namespace = substr($className, 0, $lastNsPos); $className = substr($className, $lastNsPos + 1); $fileName = str_replace($this->_namespaceSeparator, DIRECTORY_SEPARATOR, $namespace) . DIRECTORY_SEPARATOR; } $fileName .= str_replace('_', DIRECTORY_SEPARATOR, $className) . $this->_fileExtension; require ($this->_includePath !== null ? $this->_includePath . DIRECTORY_SEPARATOR : '') . $fileName; } } }
4.PSR-4与PSR-0的区别
(1)完整的类名中任意一部分中的下划线都是没有特殊含义的。
(2)所有类名都必须是大小写敏感的。
(3)自动加载器(autoloader)的实现一定不能抛出异常、一定不能触发任一级别的错误信息以及不应该有返回值。【在系统有多个自动加载时,不会影响其他的】
(4)完整的类名中,去掉最前面的命名空间分隔符,前面连续的一个或多个命名空间和子命名空间,作为“命名空间前缀”,其必须与至少一个“文件基目录”相对应
5.PSR-4范例
完整类名 | 命名空间前缀 | 文件基目录 | 文件路径 |
---|---|---|---|
\Acme\Log\Writer\File_Writer | Acme\Log\Writer | ./acme-log-writer/lib/ | ./acme-log-writer/lib/File_Writer.php |
\Aura\Web\Response\Status | Aura\Web | /path/to/aura-web/src/ | /path/to/aura-web/src/Response/Status.php |
\Symfony\Core\Request | Symfony\Core | ./vendor/Symfony/Core/ | ./vendor/Symfony/Core/Request.php |
\Zend\Acl | Zend | /usr/includes/Zend/ | /usr/includes/Zend/Acl.php |
6.composer示例
{ "autoload": { "psr-0": { "Foo": "src/", }, "psr-4": { "Foo\\": "src/", } } }
如果加载这个类时Foo\\Bar\\Baz
PSR-0的查找路径是:src/Foo/Bar/Baz.php 即路径包含了命名空间部分
PSR-4的查找路径是:src/Bar/Baz.php 即路径不包含命名空间部分