PHP类中的重要知识点

1. __construct: 

     内置构造函数，在对象被创建时自动调用。见如下代码：

<?phpclass ConstructTest {    private $arg1;    private $arg2;    public function __construct($arg1, $arg2) {        $this->arg1 = $arg1;        $this->arg2 = $arg2;        print "__construct is called...\n";    }    public function printAttributes() {        print '$arg1 = '.$this->arg1.' $arg2 = '.$this->arg2."\n";    }}$testObject = new ConstructTest("arg1","arg2"); $testObject->printAttributes();

     运行结果如下：

Stephens-Air:Desktop$ php Test.php __construct is called...$arg1 = arg1 $arg2 = arg2

2. parent: 

     用于在子类中直接调用父类中的方法，功能等同于Java中的super。 

<?phpclass BaseClass {    protected $arg1;    protected $arg2;    function __construct($arg1, $arg2) {        $this->arg1 = $arg1;        $this->arg2 = $arg2;        print "__construct is called...\n";    }    function getAttributes() {        return '$arg1 = '.$this->arg1.' $arg2 = '.$this->arg2;    }}class SubClass extends BaseClass {    protected $arg3;    function __construct($baseArg1, $baseArg2, $subArg3) {        parent::__construct($baseArg1, $baseArg2);        $this->arg3 = $subArg3;    }    function getAttributes() {        return parent::getAttributes().' $arg3 = '.$this->arg3;    }}$testObject = new SubClass("arg1","arg2","arg3"); print $testObject->getAttributes()."\n";

     运行结果如下：

Stephens-Air:Desktop$ php Test.php __construct is called...$arg1 = arg1 $arg2 = arg2 $arg3 = arg3

3. self:

     在类内调用该类静态成员和静态方法的前缀修饰，对于非静态成员变量和函数则使用this。 

<?phpclass StaticExample {    static public $arg1 = "Hello, This is static field.\n";    static public function sayHello() {        print self::$arg1;    }}print StaticExample::$arg1;StaticExample::sayHello();

     运行结果如下：

Stephens-Air:Desktop$ php Test.php Hello, This is static field.Hello, This is static field.

4. static:

     这里介绍的static关键字主要用于PHP 5.3以上版本新增的延迟静态绑定功能。请看一下代码和关键性注释。

<?phpabstract class Base {    public static function getInstance() {        //这里的new static()实例化的是调用该静态方法的当前类。        return new static();    }    abstract public function printSelf(); }class SubA extends Base {    public function printSelf() {        print "This is SubA::printSelf.\n";    }}class SubB extends Base {    public function printSelf() {        print "This is SubB::printSelf.\n";    }}SubA::getInstance()->printSelf();SubB::getInstance()->printSelf();

     运行结果如下：

Stephens-Air:Desktop$ php Test.php This is SubA::printSelf.This is SubB::printSelf.

     static关键字不仅仅可以用于实例化。和self和parent一样，static还可以作为静态方法调用的标识符，甚至是从非静态上下文中调用。在该场景下，self仍然表示的是当前方法所在的类。见如下代码： 

<?phpabstract class Base {    private $ownedGroup;    public function __construct() {        //这里的static和上面的例子一样，表示当前调用该方法的实际类。        //需要另外说明的是，这里的getGroup方法即便不是静态方法，也会得到相同的结果。然而倘若        //getGroup真的只是普通类方法，那么这里还是建议使用$this。        $this->ownedGroup = static::getGroup();    }    public function printGroup() {        print "My Group is ".$this->ownedGroup."\n";    }    public static function getInstance() {        return new static();    }    public static function getGroup() {        return "default";    }}class SubA extends Base {}class SubB extends Base {    public static function getGroup() {        return "SubB";    }}SubA::getInstance()->printGroup();SubB::getInstance()->printGroup(); 

     运行结果如下：

Stephens-Air:Desktop$ php Test.php My Group is defaultMy Group is SubB

5. __destruct:

     析构方法的作用和构造方法__construct刚好相反，它只是在对象被垃圾收集器收集之前自动调用，我们可以利用该方法做一些必要的清理工作。

<?phpclass TestClass {    function __destruct() {        print "TestClass destructor is called.\n";    }}$testObj = new TestClass();unset($testObj);print "Application will exit.\n";

     运行结果如下：

Stephens-Air:Desktop$ php Test.php TestClass destructor is called.Application will exit.

6. __clone:

     在PHP 5之后的版本中，对象之间的赋值为引用赋值，即赋值后的两个对象将指向同一地址空间，如果想基于对象赋值，可以使用PHP提供的clone方法。该方法将当前对象浅拷贝之后的副本返回，如果想在clone的过程中完成一些特殊的操作，如深拷贝，则需要在当前类的声明中实现__clone方法，该方法在执行clone的过程中会被隐式调用。另外需要格外注意的是，__clone方法是作用再被拷贝的对象上，即赋值后的对象上执行。

<?phpclass InnerClass {    public $id = 10;    public function printSelf() {        print '$id = '.$this->id."\n";    }}class OuterClass {    public $innerClass;    public function __construct() {        $this->innerClass = new InnerClass();    }    public function __clone() {        $this->innerClass = clone $this->innerClass;        print "__clone is called.\n";    }}$outerA = new OuterClass();print "Before calling to clone.\n";$outerB = clone $outerA;print "After calling to clone.\n";$outerA->innerClass->id = 20;print "In outerA: ";$outerA->innerClass->printSelf();print "In outerB: ";$outerB->innerClass->printSelf();

     运行结果如下：

Stephens-Air:Desktop$ php Test.php Before calling to clone.__clone is called.After calling to clone.In outerA: $id = 20In outerB: $id = 10

7. const:

    PHP5可以在类中定义常量属性。和全局常量一样，一旦定义就不能改变。常量属性不需要像普通属性那样以$开头，按照惯例，只能用大写字母来命名常量。另外和静态属性一样，只能通过类而不能通过类的实例访问常量属性，引用常量时同样也不需要以$符号作为前导符。另外常量只能被赋值为基础类型，如整型，而不能指向任何对象类型。

<?phpclass TestClass {    const AVAILABLE = 0;}print "TestClass::AVAILABLE = ".TestClass::AVAILABLE."\n";

    运行结果如下：

0Stephens-Air:Desktop$ php Test.php TestClass::AVAILABLE = 0

8. __toString:

    当对象被打印时，如果该类定义了该方法，则打印该方法的返回值，否则将按照PHP的缺省行为输出打印结果。该方法类似于Java中的toString()。

<?phpclass TestClass {    public function __toString() {        return "This is TestClass::__toString.\n";    }}$testObj = new TestClass();print $testObj;

    运行结果如下：

Stephens-Air:Desktop$ php Test.php This is TestClass::__toString.

9. __get和__set:

    这两个方法用于处理类中未声明的属性访问。当对象使用者试图访问未声明的对象属性时，__get()会被调用，并带有一个包含要访问的属性名称字符串作为参数。无论从__get()方法返回什么，都会直接返回给调用者，就如同带有该值的属性存在一样。另外需要注意的是，如果属性存在，但是其访问可见性为private或protected，那么这两个拦截方法同样会被调用，反之，如果属性存在切可访问，那么直接访问属性即可，这两个方法将不再会被调用。以下为__get()拦截方法的示例代码：

<?phpclass TestClass {    private $privateField;    public $publicField;    public function __construct() {        $this->privateField = "This is a private Field.\n";        $this->publicField = "This is a public Field.\n";    }    public function __get($property) {        print "__get() is called.\n";        $method = "get${property}";        if (method_exists($this, $method)) {            return $this->$method();        }        return "This is undefined field.\n";    }    public function getPrivateField() {        return $this->privateField;    }}$testObj = new TestClass();print $testObj->privateField;print $testObj->undefinedField;print $testObj->publicField;

    运行结果如下：

Stephens-Air:Desktop$ php Test.php __get() is called.This is a private Field.__get() is called.This is undefined field.This is a public Field.

    __set()方法被调用的规则和__get()基本相同，差别是用于拦截未定义或不可见类属性的赋值操作。另外，该方法接收两个参数，分别是属性名称和要设定的值。见如下代码示例：

<?phpclass TestClass {    private $privateField;    public $publicField;    public function __construct() {        $this->privateField = "This is a private Field.\n";        $this->publicField = "This is a public Field.\n";    }    public function __get($property) {        print "__get() is called.\n";        $method = "get${property}";        if (method_exists($this, $method)) {            return $this->$method();        }        return "This is an undefined field.\n";    }    public function __set($property, $value) {        print "__set is called.\n";        $method = "set${property}";        if (method_exists($this, $method)) {            $this->$method($value);        } else {            print "This is an undefined field.\n";        }    }    public function getPrivateField() {        return $this->privateField;    }    public function setPrivateField($value) {        $this->privateField = $value;    }}$testObj = new TestClass();$testObj->privateField = "This is a private Field after set.\n";$testObj->undefinedField = "This is a undefined Field after set.\n";$testObj->publicField = "This is a public Field after set.\n";print $testObj->privateField;print $testObj->undefinedField;print $testObj->publicField;

    运行结果如下：

Stephens-Air:Desktop$ php Test.php __set is called.__set is called.This is an undefined field.__get() is called.This is a private Field after set.__get() is called.This is an undefined field.This is a public Field after set.

10. __isset和__unset:

    这两个拦截方法被调用的规则和__get()和__set()非常类似，只是用于类中不存在或不可见属性被isset()和unset()两个全局方法应用时才会被分别触发。 

<?phpclass TestClass {    private $privateField;    public $publicField;    public function __construct() {        $this->privateField = "Defined private field";        $this->publicField = "Defined public field";    }    public function __isset($property) {        print "__isset is called.\n";        return isset($this->$property);    }    public function __unset($property) {        print "__unset is called.\n";        if (isset($this->$property)) {            unset($this->$property);        }    }}$testObj = new TestClass();print 'isset($testObj->privateField) is '.(isset($testObj->privateField) ? "true" : "false")."\n";print 'isset($testObj->undefinedField) is '.(isset($testObj->undefinedField) ? "true" : "false")."\n";print 'isset($testObj->publicField) is '.(isset($testObj->publicField) ? "true" : "false")."\n";print "After unset......\n";//下面两个函数调用后，$testObj的两个对象属性均会变为不可用。//另外从输出结果来看，__unset方法仅仅被调用一次，因为publicField为可见属性，所以__unset不会因该属性而被调用。unset($testObj->privateField);unset($testObj->publicField);print 'isset($testObj->privateField) is '.(isset($testObj->privateField) ? "true" : "false")."\n";print 'isset($testObj->publicField) is '.(isset($testObj->publicField) ? "true" : "false")."\n";

    运行结果如下：

Stephens-Air:Desktop$ php Test.php __isset is called.isset($testObj->privateField) is true__isset is called.isset($testObj->undefinedField) is falseisset($testObj->publicField) is trueAfter unset......__unset is called.__isset is called.isset($testObj->privateField) is false__isset is called.isset($testObj->publicField) is false

11. __call:

    __call()方法是一个非常有用但又非常容易被滥用的拦截方法。当对象使用者试图访问当前对象未定义的成员函数时，__call()会被自动调用，同时传递两个参数，分别为函数名称和传递给调用函数的所有参数(数组)。__call方法返回的任何值都会返回给函数调用者，就如同该成员函数真实存在一样。下面给出一个非常有用的委托示例。 

<?phpclass DelegateClass {    function printMessage($arg1, $arg2) {        print "DelegateClass:delegatedMethod is called.\n";        print '$arg1 = '.$arg1.'and $arg2 = '.$arg2."\n";    }}class TestClass {    private $delegateObj;    public function __construct() {        $this->delegateObj = new DelegateClass();    }    public function __call($method, $args) {        $this->delegateObj->$method($args[0],$args[1]);    }}$testObj = new TestClass();$testObj->printMessage("hello","world");

    运行结果如下：

Stephens-Air:Desktop$ php Test.php DelegateClass:delegatedMethod is called.$arg1 = helloand $arg2 = world

    从以上示例可以看出，TestClass并未声明printMessage成员方法，但是通过__call()方法的巧妙桥接直接传递给了委托对象。个人认为该技巧为双刃剑，切勿过度使用。

12. 回调函数： 

    回调函数的应用场景无须多述，在C/C++中充斥着无数的回调函数典型用例。 这里只是简单给出PHP中回调函数的使用规则。见如下示例代码和关键性注释： 

<?phpclass Product {    public $name;    public $price;    public function __construct($name, $price) {        $this->name = $name;        $this->price = $price;    }}class ProcessSale {    private $callbacks;    function registerCallback($cb) {        if (!is_callable($cb)) {            throw new Exception("callback not callable.");        }        $this->callbacks[] = $cb;    }    function sale($product) {        print "{$product->name}: processing \n";        foreach ($this->callbacks as $cb) {            //以下两种调用方式均可。            call_user_func($cb, $product);            $cb($product);        }    }}$logger = function($product) {    print "    logging ({$product->name})\n";};$processor = new ProcessSale();$processor->registerCallback($logger);$processor->sale(new Product("shoes",6));print "\n";$processor->sale(new Product("coffee",6));

    运行结果如下：

Stephens-Air:Desktop$ php Test.php shoes: processing     logging (shoes)    logging (shoes)coffee: processing     logging (coffee)    logging (coffee)

13. use(闭包):

    在Javascript中存在大量的闭包应用，PHP中的闭包则是通过use关键字来完成的。对于闭包这个概念本身而言，简要的说就是函数内的代码可以访问其父作用域中的变量。见如下示例代码和关键性注释：

<?phpclass Product {    public $name;    public $price;    public function __construct($name, $price) {        $this->name = $name;        $this->price = $price;    }}class ProcessSale {    private $callbacks;    function registerCallback($cb) {        if (!is_callable($cb)) {            throw new Exception("callback not callable.");        }        $this->callbacks[] = $cb;    }    function sale($product) {        print "{$product->name}: processing \n";        foreach ($this->callbacks as $cb) {            $cb($product);        }    }}class Totalizer {    static function warnAmount($amt) {        $count = 0;        //注意这里的$amt和$count均为闭包变量，其中&$count是以引用的形式传递的，即一旦函数内部修改了该变量的值，        //那么下次再访问该闭包变量时，$count将为之前调用中修改后的值。        return function($product) use($amt, &$count) {            $count += $product->price;            print "     count: $count\n";            if ($count > $amt) {                print "     high price reached: {$count}\n";            }        };    }}$processor = new ProcessSale();$processor->registerCallback(Totalizer::warnAmount(8));$processor->sale(new Product("shoes",6));$processor->sale(new Product("coffee",6));

    运行结果如下：

shoes: processing      count: 6coffee: processing      count: 12     high price reached: 12

14. namespace:

    和C++中的名字空间很像，作用也一样，都是为了避免在引用较多第三方库时而带来的名字冲突问题。通过名字空间，即便两个class的名称相同，但是因为位于不同的名字空间内，他们仍然可以被精确定位和区分。第一次看到PHP的名字空间语法时，感觉和C++相比在语法上是非常非常相似的，然而在写点儿小例子做做实验的时候才发现，他们的差别还是很大的，为了避免以后忘记，所以这里特别将其记录了下来。见如下代码：

<?php//in Test2.phpnamespace nstest\test2;class Test2 {    public static function printMe() {        print 'This is nstest\test2\Test2::printSelf.'."\n";    }}<?php//in Test1.phpnamespace nstest\test1;class Test1 {    public static function printMe() {        print 'This is nstest\test1\Test1::printSelf.'."\n";    }}require "Test2.php";nstest\test2\Test2::printMe();

    运行结果如下：

bogon:TestPhp$ php Test1.php PHP Fatal error:  Class 'nstest\test1\nstest\test2\Test2' not found in /Users/liulei/PhpstormProjects/TestPhp/Test1.php on line 13

    是不是这个结果比较出乎意料，原因在哪呢？HOHO，原来PHP在进行名字空间引用的时候，如果名字空间的第一个字符不是前导斜杠(\)，那么就被自动识别为相对名字空间，在上面的代码中，Test1自身所在的名字空间是namespace nstest\test1，因此在以nstest\test2\Test2::printMe()方式调用Test2::printMe()时，PHP将自动解析为nstest\test1\nstest\test2\Test2::printMe()，即认为nstest\test2是在当前名字空间内部的。修正该问题非常简单，只需在引用时加上前导斜杠(\)即可，见以下修复后的代码：     

<?php//Test2.phpnamespace nstest\test2;class Test2 {    public static function printMe() {        print 'This is nstest\test2\Test2::printSelf.'."\n";    }}<?php//Test1.phpnamespace nstest\test1;class Test1 {    public static function printMe() {        print 'This is nstest\test1\Test1::printSelf.'."\n";    }}require "Test2.php";\nstest\test2\Test2::printMe();

    运行结果如下：

bogon:TestPhp$ php Test1.php This is nstest\test2\Test2::printSelf.

    还有一种改动方式，可以示意一下PHP中名字空间中的相对引用。这里我们可以将Test1的名字空间改为namespace nstest，其他的修改见以下代码中红色高亮部分：

<?php//Test2.phpnamespace nstest\test2;class Test2 {    public static function printMe() {        print 'This is nstest\test2\Test2::printSelf.'."\n";    }}<?php//Test1.phpnamespace nstest;class Test1 {    public static function printMe() {        print 'This is nstest\test1\Test1::printSelf.'."\n";    }}require "Test2.php";test2\Test2::printMe(); 

    运行结果等于上面正确的结果。最重要的差别就是该例使用了PHP名字空间中的相对定位。相信熟悉C++的开发者一定会想到use关键字，PHP也提供了该关键字，他们的功能是一致的，都是为了避免在后面的代码中，无需再通过全限定符(类名前加名字空间前缀)来引用其他名字空间中的类了。至于具体的语法规则，还是看看下面具体的代码和关键性注释吧。

<?php//Test2.phpnamespace nstest\test2;class Test2 {    public static function printMe() {        print 'This is nstest\test2\Test2::printSelf.'."\n";    }}<?php//Test1.phpnamespace nstest\test1;class Test1 {    public static function printMe() {        print 'This is nstest\test1\Test1::printSelf.'."\n";    }}require "Test2.php";//这里需要特别注意的是，nstest\test2已经表示名字空间绝对路径定位，不需要再加前导斜杠(\)了。//另外这里还有一个隐式规则是test2表示该名字空间的缺省别名，在引用其名字空间内的对象时需要加test2前缀。use nstest\test2;test2\Test2::printMe();//这里我们也可以给名字空间显式的指定别名，如：use nstest\test2 as test2_alias;test2_alias\Test2::printMe(); 

    运行结果如下：

bogon:TestPhp$ php Test1.php This is nstest\test2\Test2::printSelf.This is nstest\test2\Test2::printSelf.

    最后介绍一下PHP中全局名字空间的引用方式，见如下代码和关键性注释：

<?phpclass Test {    public static function printMe() {        print 'This is Global namespace Test::printSelf.'."\n";    }}//下面两行代码表示的是同一对象，即全局名字空间下的Test类，然而如果因为名字空间冲突导致第一种方式不能被PHP//编译器正常识别，那么就可以使用第二种方式显式的通知PHP，自己要引用的是全局名字空间中的Test类。Test::printMe();\Test::printMe();

    运行结果如下：

bogon:TestPhp$ php Test1.php This is Global namespace Test::printSelf.This is Global namespace Test::printSelf.

15. Reflection:

    PHP中的反射和Java中java.lang.reflect包提供的功能一样，更有意思的是，就连很多方法命名和调用方式也是非常雷同的。他们都是由一些列可以分析类、类方法和方法参数的PHP内置类组成。我们这里主要介绍的是如下几个常用的内置类：(Reflection、RelectionClass、ReflectionMethod、ReflectionParameter和ReflectionProperty)。现在我们还是一步一步来理解，即从ReflectionClass开始给出示例代码和关键性注释： 

<?phpclass TestClass {    public $publicVariable;    function publicMethod() {        print "This is publicMethod.\n";    }}function classInfo(ReflectionClass $c) {    $details = "";    //getName将返回实际的类名。    $name = $c->getName();    if ($c->isUserDefined()) {        $details .= "$name is user defined.\n";    }    if ($c->isInternal()) {        $details .= "$name is built-in.\n";    }    if ($c->isAbstract()) {        $details .= "$name is abstract class.\n";    }    if ($c->isFinal()) {        $details .= "$name is final class.\n";    }    if ($c->isInstantiable()) {        $details .= "$name can be instantiated.\n";    } else {        $details .= "$name cannot be instantiated.\n";    }    return $details;}function classSource(ReflectionClass $c) {    $path = $c->getFileName();    $lines = @file($path);    //获取类定义代码的起始行和截至行。    $from = $c->getStartLine();    $to = $c->getEndLine();    $len = $to - $from + 1;    return implode(array_slice($lines,$from - 1,$len));}print "The following is Class Information.\n";print classInfo(new ReflectionClass('TestClass'));print "\nThe following is Class Source.\n";print classSource(new ReflectionClass('TestClass'));

    运行结果如下：

bogon:TestPhp$ php reflection_test.php The following is Class Information.TestClass is user defined.TestClass can be instantiated.The following is Class Source.class TestClass {    public $publicVariable;    function publicMethod() {        print "This is publicMethod.\n";    }}

    下面让我们仍然以代码示例和关键性注释的方法继续ReflectionMethod的学习之旅。

<?phpclass TestClass {    public $publicVariable;    function __construct() {    }    private function privateMethod() {    }    function publicMethod() {        print "This is publicMethod.\n";    }    function publicMethod2(string $arg1, int $arg2) {    }}//这个函数中使用的ReflectionMethod中的方法都是非常简单直观的，就不再过多赘述了。function methodInfo(ReflectionMethod $m) {    $name = $m->getName();    $details = "";    if ($m->isUserDefined()) {        $details .= "$name is user defined.\n";    }    if ($m->isInternal()) {        $details .= "$name is built-in.\n";    }    if ($m->isAbstract()) {        $details .= "$name is abstract.\n";    }    if ($m->isPublic()) {        $details .= "$name is public.\n";    }    if ($m->isProtected()) {        $details .= "$name is protected.\n";    }    if ($m->isPrivate()) {        $details .= "$name is private.\n";    }    if ($m->isStatic()) {        $details .= "$name is static.\n";    }    if ($m->isFinal()) {        $details .= "$name is final.\n";    }    if ($m->isConstructor()) {        $details .= "$name is constructor.\n";    }    if ($m->returnsReference()) {        $details .= "$name returns a reference.\n";    }    return $details;}function methodSource(ReflectionMethod $m) {    $path = $m->getFileName();    $lines = @file($path);    $from = $m->getStartLine();    $to = $m->getEndLine();    $len = $to - $from + 1;    return implode(array_slice($lines, $from - 1, $len));}$rc = new ReflectionClass('TestClass');$methods = $rc->getMethods();print "The following is method information.\n";foreach ($methods as $method) {    print methodInfo($method);    print "\n--------------------\n";}print "The following is Method[TestClass::publicMethod] source.\n";print methodSource($rc->getMethod('publicMethod'));

    运行结果如下：

bogon:TestPhp$ php reflection_test.php The following is method information.__construct is user defined.__construct is public.__construct is constructor.--------------------privateMethod is user defined.privateMethod is private.--------------------publicMethod is user defined.publicMethod is public.--------------------publicMethod2 is user defined.publicMethod2 is public.--------------------The following is Method[TestClass::publicMethod] source.    function publicMethod() {        print "This is publicMethod.\n";    }

    让我们继续ReflectionParameter吧，他表示的是成员函数的参数信息。继续看代码吧。

<?phpclass ParamClass {}class TestClass {    function publicMethod() {        print "This is publicMethod.\n";    }    function publicMethod2(ParamClass $arg1, &$arg2, $arg3 = null) {    }}function paramInfo(ReflectionParameter $p) {    $details = "";    //这里的$declaringClass将等于TestClass。    $declaringClass = $p->getDeclaringClass();    $name = $p->getName();    $class = $p->getClass();    $position = $p->getPosition();    $details .= "\$$name has position $position.\n";    if (!empty($class)) {        $classname = $class->getName();        $details .= "\$$name must be a $classname object\n";    }    if ($p->isPassedByReference()) {        $details .= "\$$name is passed by reference.\n";    }    if ($p->isDefaultValueAvailable()) {        $def = $p->getDefaultValue();        $details .= "\$$name has default: $def\n";    }    return $details;}$rc = new ReflectionClass('TestClass');$method = $rc->getMethod('publicMethod2');$params = $method->getParameters();foreach ($params as $p) {    print paramInfo($p)."\n";}

    运行结果如下：

bogon:TestPhp$ php reflection_test.php $arg1 has position 0.$arg1 must be a ParamClass object$arg2 has position 1.$arg2 is passed by reference.$arg3 has position 2.$arg3 has default: 

    上面介绍的都是通过PHP提供的Reflection API来遍历任意class的具体信息，事实上和Java等其他语言提供的反射功能一样，PHP也同样支持通过反射类调用实际对象的方法，这里将主要应用到两个方法，分别是ReflectionClass::newInstance()来创建对象实例，另一个是ReflectionMethod::invoke()，根据对象实例和方法名执行该方法。见如下代码：

<?phpclass TestClass {    private $privateArg;    function __construct($arg) {        $this->privateArg = $arg;    }    function publicMethod() {        print '$privateArg = '.$this->privateArg."\n";    }    function publicMethod2($arg1, $arg2) {        print '$arg1 = '.$arg1.' $arg2 = '.$arg2."\n";    }}$rc = new ReflectionClass('TestClass');$testObj = $rc->newInstanceArgs(array('This is private argument.'));$method = $rc->getMethod('publicMethod');$method->invoke($testObj);$method2 = $rc->getMethod('publicMethod2');$method2->invoke($testObj,"hello","world");

    运行结果如下：

bogon:TestPhp$ php reflection_test.php $privateArg = This is private argument.$arg1 = hello $arg2 = world

    事实上ReflectionClass、ReflectionMethod和ReflectionParameter提供给我们的可用方法还有更多，这里只是给出几个最典型的方法，以便我们可以更为直观的学习和了解PHP Reflection API。相信再看完以后的代码示例之后，我们都会比较清楚，如果今后需要用到和class相关的功能，就从ReflectionClass中查找，而member function的信息则一定来自于ReflectionMethod，方法参数信息来自于ReflectionParameter。

转自 http://www.cnblogs.com/stephen-liu74/