PHP面向对象程序设计之对象生成方法详解

本文实例讲述了PHP面向对象程序设计之对象生成方法。分享给大家供大家参考，具体如下：

对象

看个例子

<?phpabstract class Employee { // 雇员  protected $name;  function __construct( $name ) {    $this->name = $name;  }  abstract function fire();}class Minion extends Employee { // 奴隶 继承 雇员  function fire() {    print "{$this->name}: I'll clear my desk/n";  }}class NastyBoss { // 坏老板  private $employees = array();  function addEmployee( $employeeName ) { // 添加员工    $this->employees[] = new Minion( $employeeName ); // 代码灵活性受到限制  }  function projectFails() {    if ( count( $this->employees ) > 0 ) {      $emp = array_pop( $this->employees );      $emp->fire(); // 炒鱿鱼    }  }}$boss = new NastyBoss();$boss->addEmployee( "harry" );$boss->addEmployee( "bob" );$boss->addEmployee( "mary" );$boss->projectFails();// output:// mary: I'll clear my desk?>

再看一个更具有灵活性的案例

<?phpabstract class Employee {  protected $name;  function __construct( $name ) {    $this->name = $name;  }  abstract function fire();}class Minion extends Employee {  function fire() {    print "{$this->name}: I'll clear my desk/n";  }}class NastyBoss {  private $employees = array();   function addEmployee( Employee $employee ) { // 传入对象    $this->employees[] = $employee;  }  function projectFails() {    if ( count( $this->employees ) ) {      $emp = array_pop( $this->employees );      $emp->fire();    }  }}// new Employee class...class CluedUp extends Employee {  function fire() {    print "{$this->name}: I'll call my lawyer/n";  }}$boss = new NastyBoss();$boss->addEmployee( new Minion( "harry" ) ); // 直接以对象作为参数，更具有灵活性$boss->addEmployee( new CluedUp( "bob" ) );$boss->addEmployee( new Minion( "mary" ) );$boss->projectFails();$boss->projectFails();$boss->projectFails();// output:// mary: I'll clear my desk// bob: I'll call my lawyer// harry: I'll clear my desk?>

单例

<?phpclass Preferences {  private $props = array();  private static $instance; // 私有的，静态属性  private function __construct() { } // 无法实例化，私有的构造函数  public static function getInstance() { // 返回对象 静态方法才可以被类访问，静态方法中要有静态属性    if ( empty( self::$instance ) ) {      self::$instance = new Preferences();    }    return self::$instance;  }  public function setProperty( $key, $val ) {    $this->props[$key] = $val;  }  public function getProperty( $key ) {    return $this->props[$key];  }}$pref = Preferences::getInstance();$pref->setProperty( "name", "matt" );unset( $pref ); // remove the reference$pref2 = Preferences::getInstance();print $pref2->getProperty( "name" ) ."/n"; // demonstrate value is not lost?>