下面我们一起来看在php 中PHP类和对象函数这 php interface_exists、class_exists、method_exists和property_exists详解，希望文章对各位同学会有所帮助。
1. interface_exists、class_exists、method_exists和property_exists:
顾名思义，从以上几个函数的命名便可以猜出几分他们的功能。我想这也是我随着对PHP的深入学习而越来越喜欢这门编程语言的原因了吧。下面先给出他们的原型声明和简短说明，更多的还是直接看例子代码吧。
bool interface_exists (string $interface_name [, bool $autoload = true ]) 判断接口是否存在，第二个参数表示在查找时是否执行__autoload。
bool class_exists (string $class_name [, bool $autoload = true ]) 判断类是否存在，第二个参数表示在查找时是否执行__autoload。
bool method_exists (mixed $object , string $method_name) 判断指定类或者对象中是否含有指定的成员函数。
bool property_exists (mixed $class , string $property) 判断指定类或者对象中是否含有指定的成员变量。
实例代码如下:
- <?php
-
- interface AnotherTestInterface {
- }
- class AnotherTestClass {
- public static function printMe() {
- print "This is Test2::printSelf.n";
- }
- public function doSomething() {
- print "This is Test2::doSomething.n";
- }
- public function doSomethingWithArgs($arg1, $arg2) {
- print 'This is Test2::doSomethingWithArgs with ($arg1 = '.$arg1.' and $arg2 = '.$arg2.").n";
- }
- }
- <?php
-
-
-
- function __autoload($classname) {
- $nomilizedClassname = strtolower(preg_replace('/([A-Z]w*)([A-Z]w*)([A-Z]w*)/','${1}_${2}_${3}',$classname));
- require strtolower($nomilizedClassname).".php";
- }
-
-
-
-
- print "The following case is tested before executing autoload.n";
- if (!class_exists('AnotherTestClass',false)) {
- print "This class doesn't exist if no autoload.n";
- }
- if (!interface_exists('AnotherTestInterface',false)) {
- print "This interface doesn't exist if no autoload.n";
- }
- print "nThe following case is tested after executing autoload.n";
- if (class_exists('AnotherTestClass',true)) {
- print "This class exists if autoload is set to true.n";
- }
- if (interface_exists('AnotherTestInterface',true)) {
- print "This interface exists if autoload is set to true.n";
- }
运行结果如下:
- bogon:TestPhp$ php class_exist_test.php
- The following case is tested before executing autoload.
- This class doesn't exist if no autoload.
- This interface doesn't exist if no autoload.
- The following case is tested after executing autoload.
- This class exists if autoload is set to true.
- This interface exists if autoload is set to true.2. get_declared_classes和get_declared_interfaces:
分别返回当前可以访问的所有类和接口，这不仅包括自定义类和接口，也包括了PHP内置类和接口。他们的函数声明非常简单，没有参数，只是返回数组。见如下实例代码：
- <?php
- interface AnotherTestInterface {
- }
- class AnotherTestClass {
- public static function printMe() {
- print "This is Test2::printSelf.n";
- }
- }
- print_r(get_declared_interfaces());
- print_r(get_declared_classes());
由于输出结果过长，而且这两个函数也比较简单，所以下面就不再给出输出结果了。
3. get_class_methods、get_class_vars和get_object_vars：
这三个函数有一个共同点，即只能获取作用域可见范围内的所有成员函数、成员变量或非静态成员变量。比如在类的内部调用，则所有成员函数或者变量都符合条件，而在类的外部，则只有共有的函数和变量可以返回。
array get_class_methods (mixed $class_name) 获取指定类中可访问的成员函数。
array get_class_vars (string $class_name) 获取指定类中可以访问的成员变量。
array get_object_vars (object $object) 获取可以访问的非静态成员变量。
代码如下:
- <?php
- function output_array($functionName, $items) {
- print "$functionName.....................n";
- foreach ($items as $key => $value) {
- print '$key = '.$key. ' => $value = '.$value."n";
- }
- }
- class TestClass {
- public $publicVar = 1;
- private $privateVar = 2;
- static private $staticPrivateVar = "hello";
- static public $staticPublicVar;
- private function privateFunction() {
- }
- function publicFunction() {
- output_array("get_class_methods",get_class_methods(__CLASS__));
- output_array('get_class_vars',get_class_vars(__CLASS__));
- output_array('get_object_vars',get_object_vars($this));
- }
- }
- $testObj = new TestClass();
- print "The following is output within TestClass.n";
- $testObj->publicFunction();
- print "nThe following is output out of TestClass.n";
- output_array('get_class_methods',get_class_methods('TestClass'));
- output_array('get_class_vars',get_class_vars('TestClass'));
- output_array('get_object_vars',get_object_vars($testObj)); 运行结果如下：
-
- bogon:TestPhp liulei$ php class_exist_test.php
- The following is output within TestClass.
- get_class_methods.....................
- $key = 0 => $value = privateFunction
- $key = 1 => $value = publicFunction
- get_class_vars.....................
- $key = publicVar => $value = 1
- $key = privateVar => $value = 2
- $key = staticPrivateVar => $value = hello
- $key = staticPublicVar => $value =
- get_object_vars.....................
- $key = publicVar => $value = 1
- $key = privateVar => $value = 2
- The following is output out of TestClass.
- get_class_methods.....................
- $key = 0 => $value = publicFunction
- get_class_vars.....................
- $key = publicVar => $value = 1
- $key = staticPublicVar => $value =
- get_object_vars.....................
- $key = publicVar => $value = 14. get_called_class和get_class:
- string get_class ([ object $object = NULL ]) www.111Cn.net获取参数对象的类名称。
- string get_called_class (void) 静态方法调用时当前的类名称。
-
- <?php
- class Base {
- static public function test() {
- var_dump(get_called_class());
- }
- }
- class Derive extends Base {
- }
- Base::test();
- Derive::test();
- var_dump(get_class(new Base()));
- var_dump(get_class(new Derive()));
- 运行结果如下：
- bogon:TestPhp$ php another_test_class.php
- string(4) "Base"
- string(6) "Derive"
- string(4) "Base"
- string(6) "Derive"
5. get_parent_class、is_a和is_subclass_of:
这三个函数都是和类的继承相关，所以我把他们归到了一起。
string get_parent_class ([ mixed $object ]) 获取参数对象的父类，如果没有父类则返回false。
bool is_a (object $object, string $class_name) 判断第一个参数对象是否是$class_name类本身或是其父类的对象。
bool is_subclass_of (mixed $object, string $class_name) 判断第一个参数对象是否是$class_name的子类。
代码如下:
- <?php
- class Base {
- static public function test() {
- var_dump(get_called_class());
- }
- }
- class Derive extends Base {
- }
- var_dump(get_parent_class(new Derive()));
- var_dump(is_a(new Derive(),'Derive'));
- var_dump(is_a(new Derive(),'Base'));
- var_dump(is_a(new Base(),'Derive'));
- var_dump(is_subclass_of(new Derive(),'Derive'));
- var_dump(is_subclass_of(new Derive(),'Base')); 运行结果如下：
-
- bogon:TestPhp$ php another_test_class.php
- string(4) "Base"
- bool(true)
- bool(true)
- bool(false)
- bool(false)
- bool(true)
|
