本文實例講述了PHP設(shè)計模式入門之狀態(tài)模式原理與實現(xiàn)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(guān)如果用程序去寫一個飲料機要怎么樣實現(xiàn)呢？

首先我們可以分享一下這部飲料機有幾種狀態(tài)

一、沒有錢的狀態(tài)

二、有錢的狀態(tài)

三、售出的狀態(tài)

四、銷售一空的狀態(tài)

好吧，知道了這些狀態(tài)之后我們開始寫代碼了！

JuiceMachine.php

<?php/** * 飲料機 * @author ben * */class JuiceMachine{ /** * 糖果機一共存在四種狀態(tài)：沒錢，有錢，成功售出以及銷售一空 * * 沒錢的狀態(tài) * @var INT */ const NOMONEY = 0; /** * 有錢的狀態(tài) * @var INT */ const HASMONEY = 1; /** * 成功售出的狀態(tài) * @var INT */ const SOLD = 2; /** * 銷售一空的狀態(tài) * @var INT */ const SOLDOUT = 3; /** * 記錄糖果機當(dāng)前的狀態(tài)，初始化狀態(tài)為售空 * @var INT */ private $_state = JuiceMachine::SOLDOUT; /** * 該變量用于記錄飲料機中飲料的數(shù)量 */ private $_count; /** * 構(gòu)造方法，最主要是用來初始化count和state屬性的 */ public function __construct($count){ $this->_count = $count; //當(dāng)飲料機中的飲料數(shù)量大于零時，將飲料機的狀態(tài)重置為沒有錢的狀態(tài)。 if($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 />'; } } /** * 點擊飲料對應(yīng)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(tài)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(fā)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(shù)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(tài)重置為銷售一空 $this->_state = JuiceMachine::SOLDOUT; }else{ //將飲料機的狀態(tài)重置為沒有錢 $this->_state = JuiceMachine::NOMONEY; } }elseif($this->_state == JuiceMachine::SOLDOUT){ //其實這種情況不應(yīng)該出現(xiàn) echo 'opps, it appears that we don’t have any juice left<br />'; } }}

index.php

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

運行的結(jié)果是：

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

到目前為止我們的程序運行良好，沒有出現(xiàn)什么問題，但是從這些多重的if判斷中你是否嗅到了壞代碼的味道呢？有一天問題終于出現(xiàn)了，老板希望當(dāng)用戶點擊按鈕時有10%的概率拿到兩瓶飲料，我們需要為飲料機多加一個狀態(tài)，這時去修改代碼就成為了一種災(zāi)難，而且很可能會影響到之前的代碼，帶來新的bug，看看狀態(tài)模式如何幫助我們度過難關(guān)吧！

狀態(tài)模式的官方定義是：狀態(tài)模式允許對象在內(nèi)部狀態(tài)改變是改變它的行為，對象看起來好像是修改了它的類

用uml類圖表示如下：

在我們這個項目中的實際類圖如下：

具體實現(xiàn)代碼：

State.php

<?phpinterface State{ /** * 插入硬幣 */ public function insertCoin(); /** * 回退硬幣 */ public function retreatCoin(); /** * 點擊按鈕 */ public function clickButton(); /** * 發(fā)放飲料 */ public function dispend();}

NomoneyState.php

<?phprequire_once ’State.php’;class NomoneyState implements State{ /** * 飲料機的實例 * * @var object */ private $_juiceMachine; /** * 構(gòu)造方法，主要用于初始化飲料機實例 * */ public function __construct($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(tài)切換成有錢的狀態(tài) $this->_juiceMachine->setState($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

<?phprequire_once ’State.php’; class HasmoneyState implements State{ /** * 飲料機的實例 * * @var object */ private $_juiceMachine; /** * 構(gòu)造方法，主要用于初始化飲料機實例 */ public function __construct($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(tài)為售出模式 $rand = mt_rand(0, 0); // 當(dāng)隨機數(shù)為0（即1/10的概率）并且飲料機中還有1瓶以上的飲料時 if ($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

<?phprequire_once ’State.php’;class SoldoutState implements State{ /** * 飲料機的實例 * * @var object */ private $_juiceMachine; /** * 構(gòu)造方法，主要用于初始化飲料機實例 * */ public function __construct($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

<?phprequire_once ’State.php’;class SoldState implements State{ /** * 飲料機的實例 * * @var object */ private $_juiceMachine; /** * 構(gòu)造方法，主要用于初始化飲料機實例 * */ public function __construct($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(tài)重置為銷售一空 $this->_juiceMachine->setState($this->_juiceMachine->getSoldoutState()); }else{ //將飲料機的狀態(tài)重置為沒有錢 $this->_juiceMachine->setState($this->_juiceMachine->getNomoneyState()); } } }

WinnerState.php

<?phprequire_once ’State.php’; class WinnerState implements State{ /** * 飲料機的實例 * * @var object */ private $_juiceMachine; /** * 構(gòu)造方法，主要用于初始化飲料機實例 */ public function __construct($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(tài)重置為銷售一空$this->_juiceMachine->setState($this->_juiceMachine->getSoldoutState()); } else {// 將飲料機的狀態(tài)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(tài)重置為銷售一空 $this->_juiceMachine->setState($this->_juiceMachine->getSoldoutState()); } }}

JuiceMachine.php

<?phprequire_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(dāng)前的狀態(tài)，初始化狀態(tài)為售空 * * @var object */ private $_state; /** * 該變量用于記錄飲料機中飲料的數(shù)量 */ private $_count; /** * 構(gòu)造方法，最主要是用來初始化count和state屬性的 */ public function __construct($count) { $this->_state = new SoldoutState($this); $this->_count = $count; // 當(dāng)飲料機中的飲料數(shù)量大于零時，將飲料機的狀態(tài)重置為沒有錢的狀態(tài)。 if ($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(fā)放糖果是在用戶點擊完按鈕后機器內(nèi)部進(jìn)行的所有沒有必要再寫一個dispend方法 $this->_state->dispend(); } /** * 設(shè)置糖果機的狀態(tài) * * @param State $state */ public function setState(State $state) { $this->_state = $state; } /** * 獲取沒有錢的狀態(tài) */ public function getNomoneyState(){ return new NomoneyState($this); } /** * 獲取有錢的狀態(tài) */ public function getHasmoneyState(){ return new HasmoneyState($this); } /** * 獲取售出的狀態(tài) */ public function getSoldState(){ return new SoldState($this); } /** * 獲取銷售一空的狀態(tài) */ public function getSoldoutState(){ return new SoldoutState($this); } /** * 獲取幸運者的狀態(tài) */ public function getWinnerState(){ return new WinnerState($this); } /** * 獲取飲料機中飲料的數(shù)量 */ public function getCount(){ return $this->_count; } /** * 將飲料數(shù)量減一 */ public function decJuice(){ echo 'now you get you juice<br />'; //飲料機中的飲料數(shù)量減一 $this->_count--; } }

index.php

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

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