PHP学习记录之面向对象（Object-oriented programming，OOP）基础【接口、抽象类、静态方法等】

<?php
// 声明一个'iTemplate'接口
interface iTemplate
{
  public function setVariable($name, $var);
  public function getHtml($template);
}
// 实现接口
class Template implements iTemplate
{
  private $vars = array();
  public function setVariable($name, $var)
  {
    $this->vars[$name] = $var;
  }
  public function getHtml($template)
  {
    foreach($this->vars as $name => $value) {
      $template = str_replace('{' . $name . '}', $value, $template);
    }
    return $template;
  }
}

<?php
class MyClass
{
  const constant = '常量值';
  function showConstant() {
    echo self::constant . PHP_EOL;
  }
}
echo MyClass::constant . PHP_EOL;
$classname = "MyClass";
echo $classname::constant . PHP_EOL; // 自 5.3.0 起
$class = new MyClass();
$class->showConstant();
echo $class::constant . PHP_EOL; // 自 PHP 5.3.0 起
?>

<?php
abstract class AbstractClass
{
 // 强制要求子类定义这些方法
  abstract protected function getValue();
  abstract protected function prefixValue($prefix);
  // 普通方法（非抽象方法）
  public function printOut() {
    print $this->getValue() . PHP_EOL;
  }
}
class ConcreteClass1 extends AbstractClass
{
  protected function getValue() {
    return "ConcreteClass1";
  }
  public function prefixValue($prefix) {
    return "{$prefix}ConcreteClass1";
  }
}
class ConcreteClass2 extends AbstractClass
{
  public function getValue() {
    return "ConcreteClass2";
  }
  public function prefixValue($prefix) {
    return "{$prefix}ConcreteClass2";
  }
}
$class1 = new ConcreteClass1;
$class1->printOut();
echo $class1->prefixValue('FOO_') . PHP_EOL;
$class2 = new ConcreteClass2;
$class2->printOut();
echo $class2->prefixValue('FOO_') . PHP_EOL;
?>

<?php
abstract class AbstractClass
{
  // 我们的抽象方法仅需要定义需要的参数
  abstract protected function prefixName($name);
}
class ConcreteClass extends AbstractClass
{
  // 我们的子类可以定义父类签名中不存在的可选参数
  public function prefixName($name, $separator = ".") {
    if ($name == "Pacman") {
      $prefix = "Mr";
    } elseif ($name == "Pacwoman") {
      $prefix = "Mrs";
    } else {
      $prefix = "";
    }
    return "{$prefix}{$separator} {$name}";
  }
}
$class = new ConcreteClass;
echo $class->prefixName("Pacman"), "\n";
echo $class->prefixName("Pacwoman"), "\n";
?>

<?php
class Foo {
 public static $my_static = 'foo';
 public function staticValue() {
   return self::$my_static;
 }
}
print Foo::$my_static . PHP_EOL;
$foo = new Foo();
print $foo->staticValue() . PHP_EOL;
?>

<?php
class BaseClass {
  public function test() {
    echo "BaseClass::test() called" . PHP_EOL;
  }
  final public function moreTesting() {
    echo "BaseClass::moreTesting() called" . PHP_EOL;
  }
}
class ChildClass extends BaseClass {
  public function moreTesting() {
    echo "ChildClass::moreTesting() called" . PHP_EOL;
  }
}
// 报错信息 Fatal error: Cannot override final method BaseClass::moreTesting()
?>

<?php
class BaseClass {
  function __construct() {
    print "BaseClass 类中构造方法" . PHP_EOL;
  }
}
class SubClass extends BaseClass {
  function __construct() {
    parent::__construct(); // 子类构造方法不能自动调用父类的构造方法
    print "SubClass 类中构造方法" . PHP_EOL;
  }
}
class OtherSubClass extends BaseClass {
  // 继承 BaseClass 的构造方法
}
// 调用 BaseClass 构造方法
$obj = new BaseClass();
// 调用 BaseClass、SubClass 构造方法
$obj = new SubClass();
// 调用 BaseClass 构造方法
$obj = new OtherSubClass();
?>