状态模式

合集 - 设计模式(26)

1.面向对象程序设计中类与类的关系2024-12-292.单一职责原则2024-12-293.建造者模式2024-12-294.抽象工厂模式2024-12-295.工厂方法模式2024-12-296.女娲造人2024-12-297.原型模式2024-12-298.组合模式2024-12-299.装饰模式2024-12-2910.单例模式2024-12-2911.适配器模式2024-12-2912.桥接模式2024-12-2913.外观模式2024-12-2914.享元模式2024-12-2915.代理模式2024-12-2916.职责链模式2024-12-2917.命令模式2024-12-2918.解释器模式2024-12-2919.迭代器模式2024-12-2920.中介者模式2024-12-2921.备忘录模式2024-12-2922.观察者模式2024-12-29

23.状态模式2024-12-29

24.策略模式2024-12-2925.模板方法模式2024-12-2926.访问者模式2024-12-29

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实验 22：状态模式

本次实验属于模仿型实验，通过本次实验学生将掌握以下内容： 

1、理解状态模式的动机，掌握该模式的结构；

2、能够利用状态模式解决实际问题。

 

[实验任务一]：银行账户

 

用Java代码模拟实现课堂上的“银行账户”的实例，要求编写客户端测试代码模拟用户存款和取款，注意账户对象状态和行为的变化。

类图

 

源代码

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package com.gazikel;   public class Account {       private AccountState state;     private String owner;       public Account(String owner, double init) {         this.owner = owner;         state = new GreenState(init, this);         System.out.println("账户:" + this.owner + ",余额:" + init);       }       public void setState(AccountState state) {         this.state = state;     }     /**      * 存款      * @param amount      */     public void deposit(double amount) {         state.deposit(amount);         System.out.println("现金余额为" + this.state.balance);     }         /**      * 取款      * @param amount      */     public void withdraw(double amount){         state.withdraw(amount);         System.out.println("现金余额为" + state.balance);     } }   package com.gazikel;   /**  * 状态抽象类  */ public abstract class AccountState {       protected Account acc;     protected double balance;       public abstract void stateCheck();       public abstract void deposit(double amount);       public abstract void withdraw(double amount); } package com.gazikel;   public class GreenState extends AccountState {       public GreenState() {}       public GreenState(double amount, Account account) {         balance = amount;         acc = account;     }       @Override     public void stateCheck() {         if (balance >= 0) {             acc.setState(new GreenState(balance, acc));             System.out.println("当前为正常（绿色）状态");         } else if(balance <0 && balance >= -1000) {             acc.setState(new YellowState(balance, acc));             System.out.println("当前为欠费（黄色）状态");         } else {             acc.setState(new RedState(balance, acc));             System.out.println("当前透支（红色）状态");         }       }       @Override     public void deposit(double amount) {         balance += amount;         System.out.println(balance);         stateCheck();     }       @Override     public void withdraw(double amount) {         balance -= amount;         stateCheck();     } } package com.gazikel;   public class RedState extends AccountState {       public RedState(double amount, Account acc) {         this.balance = amount;         this.acc = acc;     }     @Override     public void stateCheck() {         if (balance >= 0) {             acc.setState(new GreenState(balance, acc));             System.out.println("当前为正常（绿色）状态");         } else if(balance <0 && balance >= -1000) {             acc.setState(new YellowState(balance, acc));             System.out.println("当前为欠费（黄色）状态");         } else {             acc.setState(new RedState(balance, acc));             System.out.println("当前透支（红色）状态");         }       }       @Override     public void deposit(double amount) {         balance += amount;         stateCheck();     }       @Override     public void withdraw(double amount) {         System.out.println("透支状态，无法取款！");     } } package com.gazikel;   public class YellowState extends AccountState {       public YellowState(double amount, Account acc) {         this.balance = amount;         this.acc = acc;     }       @Override     public void stateCheck() {         if (balance >= 0) {             acc.setState(new GreenState(balance, acc));             System.out.println("当前为正常（绿色）状态");         } else if(balance <0 && balance >= -1000) {             acc.setState(new YellowState(balance, acc));             System.out.println("当前为欠费（黄色）状态");         } else {             acc.setState(new RedState(balance, acc));             System.out.println("当前透支（红色）状态");         }     }       @Override     public void deposit(double amount) {         balance += amount;         stateCheck();       }       @Override     public void withdraw(double amount) {         balance -= amount;         stateCheck();       } }