PSR-4 实例

以下是一个实现PSR-4规范的例子：

Closure Example

/**
 * 一个具体项目实现的例子.
 * 使用SPL注册了autoload函数之后，以下代码将触发autoload函数从
 * /path/to/project/src/Baz/Qux.php 文件加载
 * \Foo\Bar\Baz\Qux 类
 *      new \Foo\Bar\Baz\Qux;
 *      
 * @param string $class The fully-qualified class name.
 * @return void
 */
spl_autoload_register(function($class) {// 项目约定的命名空间前缀$prefix = 'Foo\\Bar\\';

    // 命名空间前缀的基础目录$base_dir = __DIR__ . '/src/';

    // 这个类是否使用了命名空间前缀?$len = strlen($prefix);
    if (strncmp($prefix, $class, $len) !== 0) {
        // 没有，尝试下个已注册的 autoloaderreturn;
    }

    // 获取相对类名（截取命名空间前缀后剩下的部分）$relative_class = substr($class, $len);

    // 用base目录替换命名空间前缀；// 用目录分隔符替换命名空间分隔符；// 坠上 .php$file = $base_dir . str_replace('\\', '/', $relative_class) . '.php';

    // 如果文件存在，加载文件。if (file_exists($file)) {
        require$file;
    }
});

Class Example

以下是一个处理多命名空间的类的例子。

namespaceExample;

/**
 * 这个例子是一个针对 一个命名空间前缀对应多个base谬的通用实现。
 * 
 * foo-bar 类的包分别在以下路径下...
 * 
 *     /path/to/packages/foo-bar/
 *         src/
 *             Baz.php             # Foo\Bar\Baz
 *             Qux/
 *                 Quux.php        # Foo\Bar\Qux\Quux
 *         tests/
 *             BazTest.php         # Foo\Bar\BazTest
 *             Qux/
 *                 QuuxTest.php    # Foo\Bar\Qux\QuuxTest
 * 
 * ... 以下代码将类文件的路径添加到 \Foo\Bar\命名空间前缀下。
 * 
 *      
 *      // 初始化 loader
 *      $loader = new \Example\Psr4AutoloaderClass;
 *      
 *      // 注册 autoloader
 *      $loader->register();
 *      
 *      // 为命名空间前缀注册base目录。
 *      $loader->addNamespace('Foo\Bar', '/path/to/packages/foo-bar/src');
 *      $loader->addNamespace('Foo\Bar', '/path/to/packages/foo-bar/tests');
 * 
 * 下面的代码将触发 autoloader 尝试从
 * /path/to/packages/foo-bar/src/Qux/Quux.php 加载
 * \Foo\Bar\Qux\Quux 类:
 * 
 *      
 *      new \Foo\Bar\Qux\Quux;
 * 
 * 以下代码触发autoloader尝试从
 *  /path/to/packages/foo-bar/tests/Qux/QuuxTest.php
 * 加载\Foo\Bar\Qux\QuuxTest类 :
 * 
 *      
 *      new \Foo\Bar\Qux\QuuxTest;
 */classPsr4AutoloaderClass
{/**
     * An associative array where the key is a namespace prefix and the value
     * is an array of base directories for classes in that namespace.
     *
     * @var array
     */protected$prefixes = array();

    /**
     * Register loader with SPL autoloader stack.
     * 
     * @return void
     */publicfunctionregister()
    {
        spl_autoload_register(array($this, 'loadClass'));
    }

    /**
     * Adds a base directory for a namespace prefix.
     *
     * @param string $prefix The namespace prefix.
     * @param string $base_dir A base directory for class files in the
     * namespace.
     * @param bool $prepend If true, prepend the base directory to the stack
     * instead of appending it; this causes it to be searched first rather
     * than last.
     * @return void
     */publicfunctionaddNamespace($prefix, $base_dir, $prepend = false)
    {// normalize namespace prefix$prefix = trim($prefix, '\\') . '\\';

        // normalize the base directory with a trailing separator$base_dir = rtrim($base_dir, DIRECTORY_SEPARATOR) . '/';

        // initialize the namespace prefix arrayif (isset($this->prefixes[$prefix]) === false) {
            $this->prefixes[$prefix] = array();
        }

        // retain the base directory for the namespace prefixif ($prepend) {
            array_unshift($this->prefixes[$prefix], $base_dir);
        } else {
            array_push($this->prefixes[$prefix], $base_dir);
        }
    }

    /**
     * Loads the class file for a given class name.
     *
     * @param string $class The fully-qualified class name.
     * @return mixed The mapped file name on success, or boolean false on
     * failure.
     */publicfunctionloadClass($class)
    {// the current namespace prefix$prefix = $class;

        // work backwards through the namespace names of the fully-qualified// class name to find a mapped file namewhile (false !== $pos = strrpos($prefix, '\\')) {

            // retain the trailing namespace separator in the prefix$prefix = substr($class, 0, $pos + 1);

            // the rest is the relative class name$relative_class = substr($class, $pos + 1);

            // try to load a mapped file for the prefix and relative class$mapped_file = $this->loadMappedFile($prefix, $relative_class);
            if ($mapped_file) {
                return$mapped_file;
            }

            // remove the trailing namespace separator for the next iteration// of strrpos()$prefix = rtrim($prefix, '\\');   
        }

        // never found a mapped filereturnfalse;
    }

    /**
     * Load the mapped file for a namespace prefix and relative class.
     * 
     * @param string $prefix The namespace prefix.
     * @param string $relative_class The relative class name.
     * @return mixed Boolean false if no mapped file can be loaded, or the
     * name of the mapped file that was loaded.
     */protectedfunctionloadMappedFile($prefix, $relative_class)
    {// are there any base directories for this namespace prefix?if (isset($this->prefixes[$prefix]) === false) {
            returnfalse;
        }

        // look through base directories for this namespace prefixforeach ($this->prefixes[$prefix] as$base_dir) {

            // replace the namespace prefix with the base directory,// replace namespace separators with directory separators// in the relative class name, append with .php$file = $base_dir
                  . str_replace('\\', '/', $relative_class)
                  . '.php';

            // if the mapped file exists, require itif ($this->requireFile($file)) {
                // yes, we're donereturn$file;
            }
        }

        // never found itreturnfalse;
    }

    /**
     * If a file exists, require it from the file system.
     * 
     * @param string $file The file to require.
     * @return bool True if the file exists, false if not.
     */protectedfunctionrequireFile($file)
    {if (file_exists($file)) {
            require$file;
            returntrue;
        }
        returnfalse;
    }
}

Unit Tests

The following example is one way of unit testing the above class loader:

namespaceExample\Tests;

classMockPsr4AutoloaderClassextendsPsr4AutoloaderClass
{protected$files = array();

    publicfunctionsetFiles(array $files)
    {$this->files = $files;
    }

    protectedfunctionrequireFile($file)
    {return in_array($file, $this->files);
    }
}

classPsr4AutoloaderClassTestextends \PHPUnit_Framework_TestCase
{protected$loader;

    protectedfunctionsetUp()
    {$this->loader = new MockPsr4AutoloaderClass;

        $this->loader->setFiles(array(
            '/vendor/foo.bar/src/ClassName.php',
            '/vendor/foo.bar/src/DoomClassName.php',
            '/vendor/foo.bar/tests/ClassNameTest.php',
            '/vendor/foo.bardoom/src/ClassName.php',
            '/vendor/foo.bar.baz.dib/src/ClassName.php',
            '/vendor/foo.bar.baz.dib.zim.gir/src/ClassName.php',
        ));

        $this->loader->addNamespace(
            'Foo\Bar',
            '/vendor/foo.bar/src'
        );

        $this->loader->addNamespace(
            'Foo\Bar',
            '/vendor/foo.bar/tests'
        );

        $this->loader->addNamespace(
            'Foo\BarDoom',
            '/vendor/foo.bardoom/src'
        );

        $this->loader->addNamespace(
            'Foo\Bar\Baz\Dib',
            '/vendor/foo.bar.baz.dib/src'
        );

        $this->loader->addNamespace(
            'Foo\Bar\Baz\Dib\Zim\Gir',
            '/vendor/foo.bar.baz.dib.zim.gir/src'
        );
    }

    publicfunctiontestExistingFile()
    {$actual = $this->loader->loadClass('Foo\Bar\ClassName');
        $expect = '/vendor/foo.bar/src/ClassName.php';
        $this->assertSame($expect, $actual);

        $actual = $this->loader->loadClass('Foo\Bar\ClassNameTest');
        $expect = '/vendor/foo.bar/tests/ClassNameTest.php';
        $this->assertSame($expect, $actual);
    }

    publicfunctiontestMissingFile()
    {$actual = $this->loader->loadClass('No_Vendor\No_Package\NoClass');
        $this->assertFalse($actual);
    }

    publicfunctiontestDeepFile()
    {$actual = $this->loader->loadClass('Foo\Bar\Baz\Dib\Zim\Gir\ClassName');
        $expect = '/vendor/foo.bar.baz.dib.zim.gir/src/ClassName.php';
        $this->assertSame($expect, $actual);
    }

    publicfunctiontestConfusion()
    {$actual = $this->loader->loadClass('Foo\Bar\DoomClassName');
        $expect = '/vendor/foo.bar/src/DoomClassName.php';
        $this->assertSame($expect, $actual);

        $actual = $this->loader->loadClass('Foo\BarDoom\ClassName');
        $expect = '/vendor/foo.bardoom/src/ClassName.php';
        $this->assertSame($expect, $actual);
    }
}

以上就介绍了PSR-4 实例，包括了方面的内容，希望对PHP教程有兴趣的朋友有所帮助。