第 9 章 使用对象

9.1 创建一个对象

<?php
class myClass {
    //
}

$object1 = new myClass();
echo "\$object1 is an ".gettype($object1).".<br/>";

if (is_object($object1)) {
    echo "Really! I swear \$object1 is an object!";
}
?>

结果：

$object1 is an object.
Really! I swear $object1 is an object!

9.1.1 对象的属性

<?php
class myCar {
    public $color = "silver";
    public $make = "Mazda";
    public $model = "Protege5";
}

$car = new myCar();
echo "I drive a: $car->color $car->make $car->model<br/>";
// 改变对象的属性
$car->color = "red";
$car->make = "Porsche";
$car->model = "Boxter";
echo "I drive a: $car->color $car->make $car->model";
?>

结果：

I drive a: silver Mazda Protege5
I drive a: red Porsche Boxter

9.1.2 对象方法

具有方法的一个类

<?php
class myClass {
    function sayHello() {
        echo "HELLO!";
    }
}
$object1 = new myClass();
$object1->sayHello();
?>

结果：

HELLO!

在一个方法中访问类属性

<?php
class myClass {
    public $name = "Jimbo";
    function sayHello() {
        echo "HELLO! My name is $this->name.";
    }
}

$object1 = new myClass();
$object1->sayHello();
?>

结果：

HELLO! My name is Jimbo.

在一个方法中改变一个属性的值

<?php
class myClass {
    public $name = "Jimbo";

    function setName($name) {
        $this->name = $name;
    }
    function sayHello() {
        echo "HELLO! My name is $this->name.";
    }
}

$object1 = new myClass();
$object1->sayHello();
echo "<br/>";
$object1->setName("Julie");
$object1->sayHello();
?>

结果

HELLO! My name is Jimbo.
HELLO! My name is Julie.

9.2 对象继承

继承其父类的一个类

<?php
class myClass {
    public $name = "Matt";

    function setName($name) {
        $this->name = $name;
    }
    function sayHello() {
        echo "HELLO! My name is $this->name.";
    }
}

class childClass extends myClass {
    //
}

$object1 = new childClass("Baby Matt");
$object1->sayHello();
?>

结果：

HELLO! My name is Baby Matt.

子类的方法覆盖了父类的方法

<?php
class myClass {
    public $name = "Matt";

    function setName($name) {
        $this->name = $name;
    }
    function sayHello() {
        echo "HELLO! My name is $this->name.";
    }
}

class childClass extends myClass {
    function sayHello() {
        echo "I will not tell you my name.";
    }
}

$object1 = new childClass("Baby Matt");
$object1->sayHello();
?>

结果：

I will not tell you my name.