實(shí)驗(yàn) 22：狀態(tài)模式

本次實(shí)驗(yàn)屬于模仿型實(shí)驗(yàn)，通過(guò)本次實(shí)驗(yàn)學(xué)生將掌握以下內(nèi)容：

1、理解狀態(tài)模式的動(dòng)機(jī)，掌握該模式的結(jié)構(gòu)；

2、能夠利用狀態(tài)模式解決實(shí)際問(wèn)題。

[實(shí)驗(yàn)任務(wù)一]：銀行賬戶

用Java代碼模擬實(shí)現(xiàn)課堂上的“銀行賬戶”的實(shí)例，要求編寫(xiě)客戶端測(cè)試代碼模擬用戶存款和取款，注意賬戶對(duì)象狀態(tài)和行為的變化。

實(shí)驗(yàn)要求：

1.      畫(huà)出對(duì)應(yīng)的類圖；

2.      提交源代碼；

3. 注意編程規(guī)范。

 

類圖:

 

 

1. 源代碼

 

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("賬戶:" + this.owner + ",余額:" + init);

    }

 

    public void setState(AccountState state) {

        this.state = state;

    }

 

    public void deposit(double amount) {

        state.deposit(amount);

        System.out.println("現(xiàn)金余額為" + this.state.balance);

    }

 

    public void withdraw(double amount) {

        state.withdraw(amount);

        System.out.println("現(xiàn)金余額為" + state.balance);

    }

}

 

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);

}

 

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("當(dāng)前為正常（綠色）狀態(tài)");

        } else if (balance < 0 && balance >= -1000) {

            acc.setState(new YellowState(balance, acc));

            System.out.println("當(dāng)前為欠費(fèi)（黃色）狀態(tài)");

        } else {

            acc.setState(new RedState(balance, acc));

            System.out.println("當(dāng)前透支（紅色）狀態(tài)");

        }

    }

 

    @Override

    public void deposit(double amount) {

        balance += amount;

        System.out.println(balance);

        stateCheck();

    }

 

    @Override

    public void withdraw(double amount) {

        balance -= amount;

        stateCheck();

    }

}

 

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("當(dāng)前為正常（綠色）狀態(tài)");

        } else if (balance < 0 && balance >= -1000) {

            acc.setState(new YellowState(balance, acc));

            System.out.println("當(dāng)前為欠費(fèi)（黃色）狀態(tài)");

        } else {

            acc.setState(new RedState(balance, acc));

            System.out.println("當(dāng)前透支（紅色）狀態(tài)");

        }

    }

 

    @Override

    public void deposit(double amount) {

        balance += amount;

        stateCheck();

    }

 

    @Override

    public void withdraw(double amount) {

        System.out.println("透支狀態(tài)，無(wú)法取款！");

    }

}

 

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("當(dāng)前為正常（綠色）狀態(tài)");

        } else if (balance < 0 && balance >= -1000) {

            acc.setState(new YellowState(balance, acc));

            System.out.println("當(dāng)前為欠費(fèi)（黃色）狀態(tài)");

        } else {

            acc.setState(new RedState(balance, acc));

            System.out.println("當(dāng)前透支（紅色）狀態(tài)");

        }

    }

 

    @Override

    public void deposit(double amount) {

        balance += amount;

        stateCheck();

    }

 

    @Override

    public void withdraw(double amount) {

        balance -= amount;

        stateCheck();

    }

}

public class Client {

    public static void main(String[] args) {

        Account acc = new Account("gazikel", 2500);

 

        System.out.println("==========綠色狀態(tài)存錢(qián)===========");

        acc.deposit(1500);

        System.out.println("------------------------------");

 

        // 綠色狀態(tài)取錢(qián)

        System.out.println("==========綠色狀態(tài)取錢(qián)===========");

        acc.withdraw(4500);

        System.out.println("------------------------------");

 

        // 黃色狀態(tài)存錢(qián)

        System.out.println("==========黃色狀態(tài)存錢(qián)===========");

        acc.deposit(100);

        System.out.println("------------------------------");

 

        // 黃色狀態(tài)取錢(qián)

        System.out.println("==========黃色狀態(tài)取錢(qián)===========");

        acc.withdraw(700);

        System.out.println("------------------------------");

 

        // 紅色狀態(tài)取錢(qián)

        System.out.println("==========紅色狀態(tài)取錢(qián)===========");

        acc.withdraw(100);

 

        // 紅色狀態(tài)存錢(qián)

        System.out.println("==========紅色狀態(tài)存錢(qián)===========");

        acc.deposit(1000);

    }

}

 

}