Laravel学习笔记之PHP反射(Reflection) (上)

时间:2022-10-26 21:22:59

Laravel学习笔记之PHP反射(Reflection) (上)

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说明:Laravel中经常使用PHP的反射特性来设计代码,本文主要学习PHP的反射特性,来提高写代码时的设计质量。PHP提供一套检测class, interface, trait, property, method的两个工具包:Introspection FunctionsReflection API,类似于探针一样的东西来探测这些一等公民。本文先看下Introspection Functions的使用。

开发环境: Laravel5.3 + PHP7

Introspection Functions

Introspection Functions是用来操作object class的一些函数,PHP提供了大量的Introspection Functions来操作class, interface, trait, method, property:

  1. class_exists()

  2. interface_exists()

  3. method_exists()

  4. property_exists()

  5. trait_exists()

  6. class_alias()

  7. get_class()

  8. get_parent_class()

  9. get_called_class()

  10. get_class_methods()

  11. get_class_vars()

  12. get_object_vars()

  13. is_subclass_of()

  14. is_a()

class_exists()

Laravel源码中好多个地方使用到class_exists()方法来判断指定类是否存在,如\Illuminate\Database\Connection::isDoctrineAvailable()的源码:

    public function isDoctrineAvailable() { return class_exists('Doctrine\DBAL\Connection'); // Doctrine\DBAL\Connection::class类是否存在,大小写不敏感 }

写个PHPUnit测试下(爆绿灯,说明是正确的,这里不截图了。后面所有Introspection的测试都放在IntrospectionTest这个单元测试里):

namespace MyRightCapital\Container\Tests; class IntrospectionTest extends \PHPUnit_Framework_TestCase { public function testClassExists() { // Arrange // Actual $class_exists = class_exists(TestClassExists::class); // Assert $this->assertTrue($class_exists); } } class TestClassExists { }

interface_exists()

interface_exists()是用来检查接口是否存在,写个PHPUnit测试下,爆绿灯:

namespace MyRightCapital\Container\Tests; class IntrospectionTest extends \PHPUnit_Framework_TestCase { public function testInterfaceExists() { // Arrange // Actual $interface_exists = interface_exists(TestInterfaceExists::class); // Assert $this->assertTrue($interface_exists); } } interface TestInterfaceExists { }

method_exists()

检查类的方法(private,protected,public)是否存在于指定的类对象或类名中,Laravel中很多处用到了这个函数,如Application中的register()检查service provider中register是否存在,和bootProvider()中检查service provider中boot()方法是否存在:

public function register($provider, $options = [], $force = false) { ... if (method_exists($provider, 'register')) { $provider->register(); } ... } protected function bootProvider(ServiceProvider $provider) { if (method_exists($provider, 'boot')) { return $this->call([$provider, 'boot']); } }

这里写个PHPUnit测试下,爆绿灯:

    public function testMethodExists() { // Arrange $test_class_exists = new TestClassExists(); // Actual $object_method_exists1 = method_exists($test_class_exists, 'testPrivateMethodExists'); $object_method_exists2 = method_exists($test_class_exists, 'testProtectedMethodExists'); $object_method_exists3 = method_exists($test_class_exists, 'testPublicMethodExists'); $classname_method_exists1 = method_exists(TestClassExists::class, 'testPrivateMethodExists'); $classname_method_exists2 = method_exists(TestClassExists::class, 'testProtectedMethodExists'); $classname_method_exists3 = method_exists(TestClassExists::class, 'testPublicMethodExists'); // Assert $this->assertTrue($object_method_exists1); $this->assertTrue($object_method_exists2); $this->assertTrue($object_method_exists3); $this->assertTrue($classname_method_exists1); $this->assertTrue($classname_method_exists2); $this->assertTrue($classname_method_exists3); } class TestClassExists { private function testPrivateMethodExists() { } protected function testProtectedMethodExists() { } public function testPublicMethodExists() { } }

property_exists()

检查该属性(private, protected, public)是否存在于类对象或类名中,Laravel很多地方用到了该函数,如\Illuminate\Foundation\Auth\RedirectsUsers::redirectPath()源码:

    public function redirectPath() { return property_exists($this, 'redirectTo') ? $this->redirectTo : '/home'; }

写个PHPUnit测试下该函数,爆绿灯:

    // class IntrospectionTest public function testPropertyExists() { // Arrange $test_class_exists = new TestClassExists(); // Actual $private_property1 = property_exists($test_class_exists, 'testPrivatePropertyExists'); $private_property2 = property_exists(TestClassExists::class, 'testPrivatePropertyExists'); $protected_property1 = property_exists($test_class_exists, 'testProtectedPropertyExists'); $protected_property2 = property_exists(TestClassExists::class, 'testProtectedPropertyExists'); $public_property1 = property_exists($test_class_exists, 'testPublicPropertyExists'); $public_property2 = property_exists(TestClassExists::class, 'testPublicPropertyExists'); // Assert $this->assertTrue($private_property1); $this->assertTrue($private_property2); $this->assertTrue($protected_property1); $this->assertTrue($protected_property2); $this->assertTrue($public_property1); $this->assertTrue($public_property2); } class TestClassExists { private $testPrivatePropertyExists; protected $testProtectedPropertyExists; public $testPublicPropertyExists; }

trait_exists()

检查trait是否存在,写下PHPUnit测试,爆绿灯:

    // class IntrospectionTest public function testTraitExists() { // Arrange // Actual $test_trait_exists = trait_exists(TestTraitExists::class); // Assert $this->assertTrue($test_trait_exists); } trait TestTraitExists { }

class_alias()

给指定类取别名,Laravel中只有一处使用了class_alias(),用来给config/app.php中$aliases[ ]注册别名,可看下Laravel学习笔记之bootstrap源码解析,看下Laravel中如何使用的:

    public function load($alias) { if (isset($this->aliases[$alias])) { return class_alias($this->aliases[$alias], $alias); } }

写个PHPUnit测试,爆绿灯:

    public function testClassAlias() { // Arrange class_alias(TestClassExists::class, 'MyRightCapital\Container\Tests\AliasTestClassExists'); $test_class_exists = new TestClassExists(); // Actual $actual = new AliasTestClassExists(); //Assert $this->assertInstanceOf(TestClassExists::class, $actual); $this->assertInstanceOf(AliasTestClassExists::class, $test_class_exists); }

get_class()

get_class()获取对象的类名,这个函数在Laravel中大量地方在用了,如Application::getProvider($provider)方法,是个很好用的方法:

    public function getProvider($provider) { $name = is_string($provider) ? $provider : get_class($provider); return Arr::first($this->serviceProviders, function ($value) use ($name) { return $value instanceof $name; }); }

写个PHPUnit测试,爆绿灯:

    public function testGetClass() { // Arrange $test_class_exists = new TestClassExists(); // Actual $class_name = get_class($test_class_exists); // Assert $this->assertSame(TestClassExists::class, $class_name); }

get_parent_class()

get_parent_class()是用来获取类的父类名,目前Laravel中还没用到这个函数,传入的可以是子类对象或者子类名,写个PHPUnit测试下:

    // namespace MyRightCapital\Container\Tests; // class IntrospectionTest extends \PHPUnit_Framework_TestCase public function testGetParentClass() { // Arrange $child_class = new ChildClass(); // Actual $parent_class1 = get_parent_class($child_class); $parent_class2 = get_parent_class(ChildClass::class); // Assert $this->assertSame(ParentClass::class, $parent_class1); $this->assertSame(ParentClass::class, $parent_class2); } class ChildClass extends ParentClass { } class ParentClass { }

get_called_class()

get_called_class()获取后期静态绑定类即实际调用类的名称,Laravel中还没使用到该函数,不妨写个测试看下如何使用:

    // namespace MyRightCapital\Container\Tests; // class IntrospectionTest extends \PHPUnit_Framework_TestCase public function testGetCalledClass() { // Arrange $child_class = new ChildClass(); $parent_class = new ParentClass(); // Actual $child_called_class = $child_class->testGetCalledClass(); $parent_called_class = $parent_class->testGetCalledClass(); // Assert $this->assertSame(ChildClass::class, $child_called_class); $this->assertSame(ParentClass::class, $parent_called_class); } class ChildClass extends ParentClass { } class ParentClass { public function testGetCalledClass() { return get_called_class(); } }

get_class_methods()

get_class_methods()用来获取类的方法名组成一个数组(测试只能是public),Laravel只有一处用到了该方法\Illuminate\Database\Eloquent\Model::cacheMutatedAttributes() :line 3397,这里写个PHPUnit测试,爆绿灯:

    public function testGetClassMethod() { // Arrange $get_class_methods1 = get_class_methods(ChildClass::class); $get_class_methods2 = get_class_methods(new ChildClass()); // Actual // Assert $this->assertFalse(in_array('testPrivateGetClassMethod', $get_class_methods1, true)); $this->assertFalse(in_array('testPrivateGetClassMethod', $get_class_methods2, true)); $this->assertFalse(in_array('testProtectedGetClassMethod', $get_class_methods1, true)); $this->assertFalse(in_array('testProtectedGetClassMethod', $get_class_methods2, true)); $this->assertTrue(in_array('testPublicGetClassMethod', $get_class_methods1, true)); $this->assertTrue(in_array('testPublicGetClassMethod', $get_class_methods2, true)); $this->assertTrue(in_array('testGetCalledClass', $get_class_methods1, true)); $this->assertTrue(in_array('testGetCalledClass', $get_class_methods2, true)); } class ChildClass extends ParentClass { private function testPrivateGetClassMethod() { } protected function testProtectedGetClassMethod() { } public function testPublicGetClassMethod() { } }

get_class_vars()

get_class_vars()只会读取类的public属性组成一个数组,类似于get_class_methods(),若属性没有默认值就为null,目前Laravel中还未使用,看下PHPUnit测试:

    public function testGetClassVars() { // Arrange // Actual $class_vars = get_class_vars(ChildClass::class); // Assert $this->assertArrayNotHasKey('privateNoDefaultVar', $class_vars); $this->assertArrayNotHasKey('privateDefaultVar', $class_vars); $this->assertArrayNotHasKey('protectedNoDefaultVar', $class_vars); $this->assertArrayNotHasKey('protectedDefaultVar', $class_vars); $this->assertEmpty($class_vars['publicNoDefaultVar']); $this->assertEquals('public_laravel', $class_vars['publicDefaultVar']); } class ChildClass extends ParentClass { private $privateNoDefaultVar; private $privateDefaultVar = 'private_laravel'; protected $protectedNoDefaultVar; protected $protectedDefaultVar = 'protected_laravel'; public $publicNoDefaultVar; public $publicDefaultVar = 'public_laravel'; } 

get_object_vars()

get_object_vars()只会读取对象的public属性组成一个数组,类似于get_class_vars(), get_class_methods(),且属性没有默认值就是null,Laravel中只有一处使用到\Illuminate\Mail\Jobs\HandleQueuedMessage::__sleep() :line 78,写个PHPUnit测试下,爆绿灯:

    public function testGetObjectVars() { // Arrange $get_object_vars = new TestGetObjectVars(1, 2, 3); // Actual $object_vars = get_object_vars($get_object_vars); // Assert $this->assertArrayNotHasKey('x', $object_vars); $this->assertArrayNotHasKey('y', $object_vars); $this->assertEquals(3, $object_vars['z']); $this->assertArrayNotHasKey('dot1', $object_vars); $this->assertArrayNotHasKey('dot2', $object_vars); $this->assertArrayNotHasKey('circle1', $object_vars); $this->assertArrayNotHasKey('circle2', $object_vars); $this->assertEquals(10, $object_vars['line1']); $this->assertEmpty($object_vars['line2']); } class TestGetObjectVars { private $x; protected $y; public $z; private $dot1 = 10; private $dot2; protected $circle1 = 20; protected $circle2; public $line1 = 10; public $line2; public function __construct($x, $y, $z) { $this->x = $x; $this->y = $y; $this->z = $z; } }

is_subclass_of()

is_subclass_of()用来判断给定类对象是否是另一给定类名的子类,Laravel中有用到,这里写下PHPUnit测试,爆绿灯:

    public function testIsSubclassOf() { // Arrange $child_class = new ChildClass(); // Actual $is_subclass = is_subclass_of($child_class, ParentClass::class); // Assert $this->assertTrue($is_subclass); }

is_a()

is_a()用来判定给定类对象是否是另一给定类名的对象或是子类,和is_subclass_of()有点类似,只是is_a()还可以判定是不是该类的对象,is_a()类似于instanceof操作符,Laravel中还没用到这个方法,这里写个PHPUnit测试,爆绿灯:

    public function testIsA() { // Arrange $child_class = new ChildClass(); // Actual $is_object = is_a($child_class, ChildClass::class); $is_subclass = is_a($child_class, ParentClass::class); // Assert $this->assertTrue($is_object); $this->assertTrue($is_subclass); }

最后,给下整个PHPUnit的测试代码:

<?php namespace MyRightCapital\Container\Tests; class IntrospectionTest extends \PHPUnit_Framework_TestCase { public function testClassExists() { // Arrange // Actual $class_exists = class_exists(TestClassExists::class); // Assert $this->assertTrue($class_exists); } public function testInterfaceExists() { // Arrange // Actual $interface_exists = interface_exists(TestInterfaceExists::class); // Assert $this->assertTrue($interface_exists); } public function testMethodExists() { // Arrange $test_class_exists = new TestClassExists(); // Actual $object_method_exists1 = method_exists($test_class_exists, 'testPrivateMethodExists'); $object_method_exists2 = method_exists($test_class_exists, 'testProtectedMethodExists'); $object_method_exists3 = method_exists($test_class_exists, 'testPublicMethodExists'); $classname_method_exists1 = method_exists(TestClassExists::class, 'testPrivateMethodExists'); $classname_method_exists2 = method_exists(TestClassExists::class, 'testProtectedMethodExists'); $classname_method_exists3 = method_exists(TestClassExists::class, 'testPublicMethodExists'); // Assert $this->assertTrue($object_method_exists1); $this->assertTrue($object_method_exists2); $this->assertTrue($object_method_exists3); $this->assertTrue($classname_method_exists1); $this->assertTrue($classname_method_exists2); $this->assertTrue($classname_method_exists3); } public function testPropertyExists() { // Arrange $test_class_exists = new TestClassExists(); // Actual $private_property1 = property_exists($test_class_exists, 'testPrivatePropertyExists'); $private_property2 = property_exists(TestClassExists::class, 'testPrivatePropertyExists'); $protected_property1 = property_exists($test_class_exists, 'testProtectedPropertyExists'); $protected_property2 = property_exists(TestClassExists::class, 'testProtectedPropertyExists'); $public_property1 = property_exists($test_class_exists, 'testPublicPropertyExists'); $public_property2 = property_exists(TestClassExists::class, 'testPublicPropertyExists'); // Assert $this->assertTrue($private_property1); $this->assertTrue($private_property2); $this->assertTrue($protected_property1); $this->assertTrue($protected_property2); $this->assertTrue($public_property1); $this->assertTrue($public_property2); } public function testTraitExists() { // Arrange // Actual $test_trait_exists = trait_exists(TestTraitExists::class); // Assert $this->assertTrue($test_trait_exists); } public function testClassAlias() { // Arrange class_alias(TestClassExists::class, 'MyRightCapital\Container\Tests\AliasTestClassExists'); $test_class_exists = new TestClassExists(); // Actual $actual = new AliasTestClassExists(); //Assert $this->assertInstanceOf(TestClassExists::class, $actual); $this->assertInstanceOf(AliasTestClassExists::class, $test_class_exists); } public function testGetClass() { // Arrange $test_class_exists = new TestClassExists(); // Actual $class_name = get_class($test_class_exists); // Assert $this->assertSame(TestClassExists::class, $class_name); } public function testGetParentClass() { // Arrange $child_class = new ChildClass(); // Actual $parent_class1 = get_parent_class($child_class); $parent_class2 = get_parent_class(ChildClass::class); // Assert $this->assertSame(ParentClass::class, $parent_class1); $this->assertSame(ParentClass::class, $parent_class2); } public function testGetCalledClass() { // Arrange $child_class = new ChildClass(); $parent_class = new ParentClass(); // Actual $child_called_class = $child_class->testGetCalledClass(); $parent_called_class = $parent_class->testGetCalledClass(); // Assert $this->assertSame(ChildClass::class, $child_called_class); $this->assertSame(ParentClass::class, $parent_called_class); } public function testInArray() { $this->assertTrue(in_array('a', ['a', 'b', 1], true)); } public function testGetClassMethod() { // Arrange $get_class_methods1 = get_class_methods(ChildClass::class); $get_class_methods2 = get_class_methods(new ChildClass()); // Actual // Assert $this->assertFalse(in_array('testPrivateGetClassMethod', $get_class_methods1, true)); $this->assertFalse(in_array('testPrivateGetClassMethod', $get_class_methods2, true)); $this->assertFalse(in_array('testProtectedGetClassMethod', $get_class_methods1, true)); $this->assertFalse(in_array('testProtectedGetClassMethod', $get_class_methods2, true)); $this->assertTrue(in_array('testPublicGetClassMethod', $get_class_methods1, true)); $this->assertTrue(in_array('testPublicGetClassMethod', $get_class_methods2, true)); $this->assertTrue(in_array('testGetCalledClass', $get_class_methods1, true)); $this->assertTrue(in_array('testGetCalledClass', $get_class_methods2, true)); } public function testGetClassVars() { // Arrange // Actual $class_vars = get_class_vars(ChildClass::class); // Assert $this->assertArrayNotHasKey('privateNoDefaultVar', $class_vars); $this->assertArrayNotHasKey('privateDefaultVar', $class_vars); $this->assertArrayNotHasKey('protectedNoDefaultVar', $class_vars); $this->assertArrayNotHasKey('protectedDefaultVar', $class_vars); $this->assertEmpty($class_vars['publicNoDefaultVar']); $this->assertEquals('public_laravel', $class_vars['publicDefaultVar']); } public function testGetObjectVars() { // Arrange $get_object_vars = new TestGetObjectVars(1, 2, 3); // Actual $object_vars = get_object_vars($get_object_vars); // Assert $this->assertArrayNotHasKey('x', $object_vars); $this->assertArrayNotHasKey('y', $object_vars); $this->assertEquals(3, $object_vars['z']); $this->assertArrayNotHasKey('dot1', $object_vars); $this->assertArrayNotHasKey('dot2', $object_vars); $this->assertArrayNotHasKey('circle1', $object_vars); $this->assertArrayNotHasKey('circle2', $object_vars); $this->assertEquals(10, $object_vars['line1']); $this->assertEmpty($object_vars['line2']); } public function testIsSubclassOf() { // Arrange $child_class = new ChildClass(); // Actual $is_subclass = is_subclass_of($child_class, ParentClass::class); // Assert $this->assertTrue($is_subclass); } public function testIsA() { // Arrange $child_class = new ChildClass(); // Actual $is_object = is_a($child_class, ChildClass::class); $is_subclass = is_a($child_class, ParentClass::class); // Assert $this->assertTrue($is_object); $this->assertTrue($is_subclass); } } class TestGetObjectVars { private $x;