PHP設計模式入門之狀態模式原理與實現方法分析

阿新 • • 發佈：2020-04-27

本文例項講述了PHP設計模式入門之狀態模式原理與實現方法。分享給大家供大家參考，具體如下：

想必大家都用過自動售賣的自動飲料機吧，塞入硬幣或紙幣，選擇想要的飲料，飲料就會在機器的下方滾出。大家有沒有相關如果用程式去寫一個飲料機要怎麼樣實現呢？

首先我們可以分享一下這部飲料機有幾種狀態

一、沒有錢的狀態

二、有錢的狀態

三、售出的狀態

四、銷售一空的狀態

好吧，知道了這些狀態之後我們開始寫程式碼了！

JuiceMachine.php

<?php
/**
 * 飲料機
 * @author ben
 *
 */
class JuiceMachine{
 /**
 * 糖果機一共存在四種狀態：沒錢，有錢，成功售出以及銷售一空
 * 
 * 沒錢的狀態
 * @var INT
 */
 const NOMONEY = 0;
 
 /**
 * 有錢的狀態
 * @var INT
 */
 const HASMONEY = 1;
 
 /**
 * 成功售出的狀態
 * @var INT
 */
 const SOLD = 2;
 
 /**
 * 銷售一空的狀態
 * @var INT
 */
 const SOLDOUT = 3;
 
 /**
 * 記錄糖果機當前的狀態，初始化狀態為售空
 * @var INT
 */
 private $_state = JuiceMachine::SOLDOUT;
 
 /**
 * 該變數用於記錄飲料機中飲料的數量
 */
 private $_count; 
 
 /**
 * 構造方法，最主要是用來初始化count和state屬性的
 */
 public function __construct($count){
   $this->_count = $count;
   //當飲料機中的飲料數量大於零時，將飲料機的狀態重置為沒有錢的狀態。
   if($this->_count > 0){
     $this->_state = JuiceMachine::NOMONEY;
   }
 }
 
 /**
 * 投入硬幣
 */
 public function insertCoin(){
   if($this->_state == JuiceMachine::HASMONEY ){
     echo "you can't insert another coin!<br />";
   }elseif($this->_state == JuiceMachine::NOMONEY){
     echo "you just insert a coin<br />";
     $this->_state = JuiceMachine::HASMONEY;
   }elseif($this->_state == JuiceMachine::SOLD){
     echo "wait a minute,we are giving you a bottle of juice<br />";
   }elseif($this->_state == JuiceMachine::SOLDOUT){
     echo "you can't insert coin,the machine is already soldout<br />";
   }
 }
 
 /**
 * 退回硬幣
 */
 public function retreatCoin(){
   if($this->_state == JuiceMachine::HASMONEY ){
     echo "coin return!<br />";
     $this->_state = JuiceMachine::NOMONEY;
   }elseif($this->_state == JuiceMachine::NOMONEY){
     echo "you have'nt inserted a coin yet<br />";
   }elseif($this->_state == JuiceMachine::SOLD){
     echo "sorry,you already clicked the botton<br />";
   }elseif($this->_state == JuiceMachine::SOLDOUT){
     echo "you have'nt inserted a coin yet<br />";
   }
 }
 
 /**
 * 點選飲料對應的按鈕
 */
 public function clickButton(){
   if($this->_state == JuiceMachine::HASMONEY ){
     echo "you clicked,we are giving you a bottle of juice...<br />";
     $this->_state = JuiceMachine::SOLD;  //改變飲料機的狀態為售出模式
     $this->dispend();
   }elseif($this->_state == JuiceMachine::NOMONEY){
     echo "you clicked,but you hav'nt inserted a coin yet<br />";
   }elseif($this->_state == JuiceMachine::SOLD){
     echo "click twice does'nt get you two bottle of juice<br />";
   }elseif($this->_state == JuiceMachine::SOLDOUT){
     echo "you clicked,but the machine is already soldout<br />";
   }
 }
 
 /**
 * 發放飲料
 */
 public function dispend(){
   if($this->_state == JuiceMachine::HASMONEY ){
     echo "please click the button first<br />";
   }elseif($this->_state == JuiceMachine::NOMONEY){
     echo "you need to pay first<br />";
   }elseif($this->_state == JuiceMachine::SOLD){
     echo "now you get you juice<br />";
     //飲料機中的飲料數量減一
     $this->_count--;
     if($this->_count <= 0){
       echo "opps,runing out of juice<br />";
       //如果這時飲料機中沒有飲料了，將飲料機的狀態重置為銷售一空
       $this->_state = JuiceMachine::SOLDOUT;
     }else{
       //將飲料機的狀態重置為沒有錢
       $this->_state = JuiceMachine::NOMONEY;
     }
   }elseif($this->_state == JuiceMachine::SOLDOUT){
     //其實這種情況不應該出現
     echo "opps,it appears that we don't have any juice left<br />";
   }
 }
}

index.php

<?php
require_once 'JuiceMachine.php';
 
$juiceMachine = new JuiceMachine(1);
 
$juiceMachine->insertCoin();
$juiceMachine->clickButton();

執行的結果是：

you just insert a coin
you clicked,we are giving you a bottle of juice...
now you get you juice
opps,runing out of juice

到目前為止我們的程式執行良好，沒有出現什麼問題，但是從這些多重的if判斷中你是否嗅到了壞程式碼的味道呢？有一天問題終於出現了，老闆希望當用戶點選按鈕時有10%的概率拿到兩瓶飲料，我們需要為飲料機多加一個狀態，這時去修改程式碼就成為了一種災難，而且很可能會影響到之前的程式碼，帶來新的bug，看看狀態模式如何幫助我們度過難關吧！

狀態模式的官方定義是：狀態模式允許物件在內部狀態改變是改變它的行為，物件看起來好像是修改了它的類

用uml類圖表示如下：

PHP設計模式入門之狀態模式原理與實現方法分析

在我們這個專案中的實際類圖如下：

PHP設計模式入門之狀態模式原理與實現方法分析

具體實現程式碼：

State.php

<?php
interface State{
  
  /**
   * 插入硬幣
   */
  public function insertCoin();
  
  /**
   * 回退硬幣
   */
  public function retreatCoin();
  
  /**
   * 點選按鈕
   */
  public function clickButton();
  
  /**
   * 發放飲料
   */
  public function dispend();
}

NomoneyState.php

<?php
require_once 'State.php';
class NomoneyState implements State{
  
  /**
   * 飲料機的例項
   * 
   * @var object
   */
  private $_juiceMachine;
  
  /**
   * 構造方法，主要用於初始化飲料機例項
   * 
   */
  public function __construct($juiceMachine){
    $this->_juiceMachine = $juiceMachine;
  }
  
 /* (non-PHPdoc)
   * @see State::insertCoin()
   */
  public function insertCoin()
  {
    // TODO Auto-generated method stub
    echo "you just insert a coin<br />";
    //將飲料機的狀態切換成有錢的狀態
    $this->_juiceMachine->setState($this->_juiceMachine->getHasmoneyState());
  }
 
 /* (non-PHPdoc)
   * @see State::retreatCoin()
   */
  public function retreatCoin()
  {
    // TODO Auto-generated method stub
    echo "you have'nt inserted a coin yet<br />";
  }
 
 /* (non-PHPdoc)
   * @see State::clickButton()
   */
  public function clickButton()
  {
    // TODO Auto-generated method stub
    echo "you clicked,but you hav'nt inserted a coin yet<br />";
  }
 
 /* (non-PHPdoc)
   * @see State::dispend()
   */
  public function dispend()
  {
    // TODO Auto-generated method stub
    echo "you need to pay first<br />";
  }
}

HasmoneyState.php

<?php
require_once 'State.php';
 
class HasmoneyState implements State
{
 
  /**
   * 飲料機的例項
   *
   * @var object
   */
  private $_juiceMachine;
 
  /**
   * 構造方法，主要用於初始化飲料機例項
   */
  public function __construct($juiceMachine)
  {
    $this->_juiceMachine = $juiceMachine;
  }
  
  /*
   * (non-PHPdoc) @see State::insertCoin()
   */
  public function insertCoin()
  {
    // TODO Auto-generated method stub
    echo "you can't insert another coin!<br />";
  }
  
  /*
   * (non-PHPdoc) @see State::retreatCoin()
   */
  public function retreatCoin()
  {
    // TODO Auto-generated method stub
    echo "coin return!<br />";
    $this->_juiceMachine->setState($this->_juiceMachine->getNomoneyState());
  }
  
  /*
   * (non-PHPdoc) @see State::clickButton()
   */
  public function clickButton()
  {
    // TODO Auto-generated method stub
    echo "you clicked,we are giving you a bottle of juice...<br />";
    // 改變飲料機的狀態為售出模式
    $rand = mt_rand(0,0);
    // 當隨機數為0（即1/10的概率）並且飲料機中還有1瓶以上的飲料時
    if ($rand == 0 && $this->_juiceMachine->getCount() > 1) {
      $this->_juiceMachine->setState($this->_juiceMachine->getWinnerState());
    } else {
      $this->_juiceMachine->setState($this->_juiceMachine->getSoldState());
    }
  }
  
  /*
   * (non-PHPdoc) @see State::dispend()
   */
  public function dispend()
  {
    // TODO Auto-generated method stub
    echo "please click the button first<br />";
  }
}

SoldoutState.php

<?php
require_once 'State.php';
class SoldoutState implements State{
  
  /**
   * 飲料機的例項
   *
   * @var object
   */
  private $_juiceMachine;
  
  /**
   * 構造方法，主要用於初始化飲料機例項
   *
   */
  public function __construct($juiceMachine){
    $this->_juiceMachine = $juiceMachine;
  }
  
 /* (non-PHPdoc)
   * @see State::insertCoin()
   */
  public function insertCoin()
  {
    // TODO Auto-generated method stub
    echo "you can't insert coin,the machine is already soldout<br />";
  }
 
 /* (non-PHPdoc)
   * @see State::retreatCoin()
   */
  public function retreatCoin()
  {
    // TODO Auto-generated method stub
    echo "you have'nt inserted a coin yet<br />";
  }
 
 /* (non-PHPdoc)
   * @see State::clickButton()
   */
  public function clickButton()
  {
    // TODO Auto-generated method stub
    echo "you clicked,but the machine is already soldout<br />";
  }
 
 /* (non-PHPdoc)
   * @see State::dispend()
   */
  public function dispend()
  {
    // TODO Auto-generated method stub
    echo "opps,it appears that we don't have any juice left<br />";
  }
}

SoldState.php

<?php
require_once 'State.php';
class SoldState implements State{
  
  /**
   * 飲料機的例項
   *
   * @var object
   */
  private $_juiceMachine;
  
  /**
   * 構造方法，主要用於初始化飲料機例項
   *
   */
  public function __construct($juiceMachine){
    $this->_juiceMachine = $juiceMachine;
  }
  
 /* (non-PHPdoc)
   * @see State::insertCoin()
   */
  public function insertCoin()
  {
    // TODO Auto-generated method stub
    echo "wait a minute,we are giving you a bottle of juice<br />";
  }
 
 /* (non-PHPdoc)
   * @see State::retreatCoin()
   */
  public function retreatCoin()
  {
    // TODO Auto-generated method stub
    echo "sorry,you already clicked the botton<br />";
  }
 
 /* (non-PHPdoc)
   * @see State::clickButton()
   */
  public function clickButton()
  {
    // TODO Auto-generated method stub
    echo "click twice does'nt get you two bottle of juice<br />";
  }
 
 /* (non-PHPdoc)
   * @see State::dispend()
   */
  public function dispend()
  {
    $this->_juiceMachine->decJuice();
    if($this->_juiceMachine->getCount() <= 0){
      echo "opps,runing out of juice<br />";
      //如果這時飲料機中沒有飲料了，將飲料機的狀態重置為銷售一空
       $this->_juiceMachine->setState($this->_juiceMachine->getSoldoutState());
    }else{
      //將飲料機的狀態重置為沒有錢
       $this->_juiceMachine->setState($this->_juiceMachine->getNomoneyState());
    }
  }
  
}

WinnerState.php

<?php
require_once 'State.php';
 
class WinnerState implements State
{
 
  /**
   * 飲料機的例項
   *
   * @var object
   */
  private $_juiceMachine;
 
  /**
   * 構造方法，主要用於初始化飲料機例項
   */
  public function __construct($juiceMachine)
  {
    $this->_juiceMachine = $juiceMachine;
  }
  
  /*
   * (non-PHPdoc) @see State::insertCoin()
   */
  public function insertCoin()
  {
    // TODO Auto-generated method stub
    echo "wait a minute,we are giving you a bottle of juice<br />";
  }
  
  /*
   * (non-PHPdoc) @see State::retreatCoin()
   */
  public function retreatCoin()
  {
    // TODO Auto-generated method stub
    echo "sorry,you already clicked the botton<br />";
  }
  
  /*
   * (non-PHPdoc) @see State::clickButton()
   */
  public function clickButton()
  {
    // TODO Auto-generated method stub
    echo "click twice does'nt get you two bottle of juice<br />";
  }
  
  /*
   * (non-PHPdoc) @see State::dispend()
   */
  public function dispend()
  {
    echo "you are a winner! you get two bottle of juice!<br />";
    $this->_juiceMachine->decJuice();
    if ($this->_juiceMachine->getCount() > 0) {
      $this->_juiceMachine->decJuice();
      if ($this->_juiceMachine->getCount() <= 0) {
        echo "opps,runing out of juice<br />";
        // 如果這時飲料機中沒有飲料了，將飲料機的狀態重置為銷售一空
        $this->_juiceMachine->setState($this->_juiceMachine->getSoldoutState());
      } else {
        // 將飲料機的狀態重置為沒有錢
        $this->_juiceMachine->setState($this->_juiceMachine->getSoldoutState());
      }
    } else {
      echo "opps,runing out of juice<br />";
      // 如果這時飲料機中沒有飲料了，將飲料機的狀態重置為銷售一空
      $this->_juiceMachine->setState($this->_juiceMachine->getSoldoutState());
    }
  }
}

JuiceMachine.php

<?php
require_once './state/NomoneyState.php';
require_once './state/HasmoneyState.php';
require_once './state/SoldState.php';
require_once './state/SoldoutState.php';
require_once './state/WinnerState.php';
 
class JuiceMachine
{
 
  /**
   * 記錄糖果機當前的狀態，初始化狀態為售空
   * 
   * @var object
   */
  private $_state;
 
  /**
   * 該變數用於記錄飲料機中飲料的數量
   */
  private $_count;
 
  /**
   * 構造方法，最主要是用來初始化count和state屬性的
   */
  public function __construct($count)
  {
    $this->_state = new SoldoutState($this);
    $this->_count = $count;
    // 當飲料機中的飲料數量大於零時，將飲料機的狀態重置為沒有錢的狀態。
    if ($this->_count > 0) {
      $this->_state = new NomoneyState($this);
    }
  }
  
  /*
   * (non-PHPdoc) @see State::insertCoin()
   */
  public function insertCoin()
  {
    // TODO Auto-generated method stub
    $this->_state->insertCoin();
  }
  
  /*
   * (non-PHPdoc) @see State::retreatCoin()
   */
  public function retreatCoin()
  {
    // TODO Auto-generated method stub
    $this->_state->retreatCoin();
  }
  
  /*
   * (non-PHPdoc) @see State::clickButton()
   */
  public function clickButton()
  {
    $this->_state->clickButton();
    //其實發放糖果是在使用者點選完按鈕後機器內部進行的所有沒有必要再寫一個dispend方法
    $this->_state->dispend();
  }
  
  /**
   * 設定糖果機的狀態
   * 
   * @param State $state
   */
  public function setState(State $state)
  {
    $this->_state = $state;
  }
  
  /**
   * 獲取沒有錢的狀態
   */
  public function getNomoneyState(){
    return new NomoneyState($this);
  }
  
  /**
   * 獲取有錢的狀態
   */
  public function getHasmoneyState(){
    return new HasmoneyState($this);
  }
  
  /**
   * 獲取售出的狀態
   */
  public function getSoldState(){
    return new SoldState($this);
  }
  
  /**
   * 獲取銷售一空的狀態
   */
  public function getSoldoutState(){
    return new SoldoutState($this);
  }
  
  /**
   * 獲取幸運者的狀態
   */
  public function getWinnerState(){
    return new WinnerState($this);
  }
  
  /**
   * 獲取飲料機中飲料的數量
   */
  public function getCount(){
    return $this->_count;
  }
  
  /**
   * 將飲料數量減一
   */
  public function decJuice(){
    echo "now you get you juice<br />";
    //飲料機中的飲料數量減一
    $this->_count--;
  }
  
}

index.php

<?php
require_once 'JuiceMachine.php';
 
$juiceMachine = new JuiceMachine(2);
 
$juiceMachine->insertCoin();
$juiceMachine->clickButton();

更多關於PHP相關內容感興趣的讀者可檢視本站專題：《php面向物件程式設計入門教程》、《PHP陣列(Array)操作技巧大全》、《PHP基本語法入門教程》、《PHP運算與運算子用法總結》、《php字串(string)用法總結》、《php+mysql資料庫操作入門教程》及《php常見資料庫操作技巧彙總》

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