关于PHP面向对象中一些方法、函数应用的代码

这篇文章主要介绍了关于PHP面向对象中的一些知识点，有着一定的参考价值，现在分享给大家，有需要的朋友可以参考一下

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 B<span>！本文来源gaodai#ma#com搞*!代#%^码网5</span><pre>搞gaodaima代码

ase {} class SubB extends Base { public static function getGroup() { return "SubB"; }} SubA::getInstance()->printGroup();SubB::getInstance()->printGroup();

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