设计模式之观察者模式&&状态模式-优快云博客

本文深入探讨了观察者模式和状态模式的概念及其在实际编程中的应用。通过具体实例，展示了观察者模式如何使对象在状态变化时通知依赖对象，以及状态模式如何简化复杂的条件逻辑。

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<?php

interface Subject {
	function attach($obj);
	function detach($name);
	function notify();
}

class Teacher implements Subject {
	private $attachArr = array();

	function __construct() {
	}

	function attach($obj) {
    	array_push($this->attachArr, $obj);
	}

	function detach($name) {
		unset($name);
	}

	function notify() {
		foreach($this->attachArr as $obj) {
			$obj->work();
		}
	}

	function setStatus($status) {
		$this->status = $status;
	}


}

interface Observe {
function work();
}

class Student implements Observe {

	function __construct($name, $work, $subjectObj) {
		$this->name = $name;
		$this->subjectObj = $subjectObj;
		$this->work = $work;
	}

	function work() {
		echo $this->subjectObj->status . "\n" .$this->name . $this->work . " \n";
	}
}
$teacher = new Teacher();
$student1 = new Student('joey', 'paly table tenice', $teacher);
$student2 = new Student('jam', 'sleeping', $teacher);

$teacher->attach($student1);
$teacher->attach($student2);
$teacher->setStatus("quitting time \n");

$teacher->notify();

以上代码为观察者模式

观察者模式为当一个对象的状态改变的时候，其他的关联对象也做出相应。

观察者模式缺点：每个观察者对象必须继承这个抽像出来的接口类(比如这里的work)，这样就造成了一些不方便，

可以通过委托实现。

<?php
//状态模式

abstract class State {
	abstract  function writeProgram(Work $work);
}

class ForenoonState extends State {
	function writeProgram(Work $work) {
	  if ($work->hour < 12) {
	     echo '当前时间是上午' . $work->hour . '工作精神百倍噢';
	  } else {
	     $work->setState(new NoonState());
		 $work->writeProgram();
	  }

	}
}

class NoonState extends State {
    function writeProgram(Work $work) {
	    if ($work->hour < 13 && $work->hour >= 12) {
		   echo '当前时间是' . $work->hour . '午饭时间有点饿';
		} else {
		   $work->setState( new AfternoonState());
		   $work->writeProgram();
		}
	}
}

class AfternoonState extends State {
    function writeProgram(Work $work) {
		if ($work->hour > 13 && $work->hour < 17) {
		   echo '当前时间是' . $work->hour . '状态不错继续努力';
		} else {
		   $work->setState(new EveningState());
		   $work->writeProgram();
		}
	}
}

class EveningState extends State {
    function writeProgram(Work $work) {
	    if ($work->finish) {
			$work->setState(new RestState());
			$work->writeProgram();
		} else {
		    if ($work->hour < 21) {
               echo '当前时间是' . $work->hour . '加班悲剧了';
			}
		}
	}
}

class RestState extends State {
    function writeProgram(Work $work) {
	    echo '当前时间是' . $work->hour . '下班回家了';
	}
}

class Work {
    private $state;
	public  $hour;
	public  $finish = false; 
	function __construct() {
	    $this->state = new ForenoonState();
	}

	function setState($state) {
		$this->state = $state;
	}

	function taskFinished() {
		$this->finish = true;
	}
	function writeProgram() {
		$this->state->writeProgram($this);
	}
}

$task = new Work();
$task->hour = 8;
$task->writeProgram();
$task->hour = 12;
$task->writeProgram();

$task->hour = 15;
$task->writeProgram();
$task->hour = 20;
$task->taskFinished();
$task->writeProgram();