php 设计模式之单例模式

在就已经应用了( )，从始到终它就只有一个工厂，单例模式不需要新建实例。
现在写一个简单的例子。

小船类boat.php

<?php
class boat {
private static $instance=null;
private $skipper;
private $personNum=0;
private $passengers=array();
private function __construct() {
}
public static function getInstance(){
if (self::$instance==null){
self::$instance=new boat();
}
return self::$instance;
}
/**
* 设置船长
*
* @param unknown_type $name
*/
public function setSkipper($name){
$this->skipper=$name;
}
/**
* 装人
*
* @param unknown_type $person
*/
public function load($person){
if (!emptyempty($person) and $this->personNum<=5){
array_push($this->passengers,$person);
$this->personNum=$this->personNum+1;
}
if ($this->personNum>5) {
echo 'this boat only load 5 person!';
} //
}
/**
* 船上装了什么人
*
* @return unknown
*/
public function whoInBoat(){
return $this->passengers;
}
}
?>

现在看看怎么样上客

<?php
include 'boat.php';
echo "从前有一条河，河里只有一条船，";
$boat1=boat::getInstance();//因为只有一条船，所以只有一个实例
echo "现在张三要到河东去,";
$boat1->load('张三');
echo "现在船上坐着：";
foreach ($boat1->whoInboat() as $who){
echo $who.'';
}
echo "现在李四也要过河东去";
$boat1->load('李四');
echo "现在船上坐着：";
foreach ($boat1->whoInboat() as $who){
echo $who.'、';
}
echo "王五以为这条河有另一条船,";
$boat2=boat::getInstance();
echo "他现在上船";
$boat2->load('王五');
echo "现在船上坐着：";
foreach ($boat1->whoInboat() as $who){
echo $who.'、';
}
?>