11.25

软件设计                  石家庄铁道大学信息学院

 

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。

实验要求：

1. 提交源代码；

2. 注意编程规范。

 

 

 

package ceshi;

 

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 ceshi;

 

/**

 * 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 ceshi;

 

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 ceshi;

 

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();

 

    }

}