设计模式之状态模式

题目

[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

C++

Account.h

#pragma once
#ifndef _ACCOUNT_H_
#define _ACCOUNT_H_
#include<iostream>
#include<string>
#include<list>
using namespace std;

class AccountState;
class Account {
private:
	string owner;
	AccountState* state;
public:
	Account(string owner, double init);
	~Account();
	void Deposit(double amount);
	void Withdraw(double amount);
	void SetState(AccountState* state);
};


#endif

AccountState.h

#pragma once
#ifndef _ACCOUNTSTATE_H_
#define _ACCOUNTSTATE_H_
#include<string>
using namespace std;
class Account;
class AccountState {
public:
	virtual ~AccountState();
	AccountState();
	virtual void Deposit(double amount) = 0;
	virtual void Withdraw(double amount) = 0;
	virtual void StateCheck() = 0;
	double balance;
	Account* acc;
};
class GreenState :public AccountState {
public:
	GreenState(AccountState* acc);
	GreenState(double balance, Account* acc);
	~GreenState();
	void Deposit(double amount);
	void Withdraw(double amount);
	void StateCheck();

};

class YellowState :public AccountState {
public:
	YellowState(AccountState* acc);
	~YellowState();
	void Deposit(double amount);
	void Withdraw(double amount);
	void StateCheck();

};

class RedState :public AccountState {
public:
	RedState(AccountState* acc);
	~RedState();
	void Deposit(double amount);
	void Withdraw(double amount);
	void StateCheck();

};
#endif

Account.cpp

#include"Account.h"
#include"AccountState.h"
#include<iostream>
#include<string>
#include<list>
#include<cstring>
#include<sstream>
using namespace std;

Account::Account(string owner, double init) {
	this->owner = owner;
	this->state = new GreenState(init, this);
	cout << "账户:" << this->owner << "初始金额" << init << endl;
}

Account::~Account() {}

void Account::SetState(AccountState* state) {
	this->state = state;
}

void Account::Deposit(double amount) {

	state->Deposit(amount);
	cout << "现金余额为" << this->state->balance << endl;
	
}

void Account::Withdraw(double amount) {
	state->Withdraw(amount);
	cout << "现金余额为" << this->state->balance << endl;
}

AccountState.cpp

#include"Account.h"
#include"AccountState.h"
#include<iostream>
using namespace std;

AccountState::AccountState() {}

AccountState::~AccountState() {}

void AccountState::Withdraw(double amount) {}

void AccountState::Deposit(double amount) {}

void AccountState::StateCheck() {}

GreenState::GreenState(AccountState* state) {
	this->balance = state->balance;
	this->acc = state->acc;
}

GreenState::GreenState(double balance, Account* acc)
{
	this->balance = balance;
	this->acc = acc;
}
GreenState::~GreenState()
{
}
void GreenState::StateCheck() {
	if (balance >= 0) {
		acc->SetState(new GreenState(this));
		cout << "当前为正常（绿色）状态" << endl;
	}
	else if (balance < 0 && balance >= -1000) {
		acc->SetState(new YellowState(this));
		cout << "当前为欠费（黄色）状态" << endl;
	}
	else {
		acc->SetState(new RedState(this));
		cout << "当前透支（红色）状态" << endl;
	}
}
void GreenState::Deposit(double amount)
{
	this->balance += amount;
	StateCheck();
}

void GreenState::Withdraw(double amount)
{
	this->balance -= amount;
	StateCheck();
}

YellowState::YellowState(AccountState* state) {
	this->balance = state->balance;
	this->acc = state->acc;
}

YellowState::~YellowState() {}

void YellowState::StateCheck() {
	if (balance >= 0) {
		acc->SetState(new GreenState(this));
		cout << "当前为正常（绿色）状态" << endl;
	}
	else if (balance < 0 && balance >= -1000) {
		acc->SetState(new YellowState(this));
		cout << "当前为欠费（黄色）状态" << endl;
	}
	else {
		acc->SetState(new RedState(this));
		cout << "当前透支（红色）状态" << endl;
	}
}

void YellowState::Deposit(double amount) {
	balance += amount;
	StateCheck();
}

void YellowState::Withdraw(double amount) {
	balance -= amount;
	StateCheck();
}

RedState::RedState(AccountState* state)
{
	this->balance = state->balance;
	this->acc = state->acc;
}
RedState::~RedState()
{
}
void RedState::StateCheck() {
	if (balance >= 0) {
		acc->SetState(new GreenState(this));
		cout << "当前为正常（绿色）状态" << endl;
	}
	else if (balance < 0 && balance >= -1000) {
		acc->SetState(new YellowState(this));
		cout << "当前为欠费（黄色）状态" << endl;
	}
	else {
		acc->SetState(new RedState(this));
		cout << "当前透支（红色）状态" << endl;
	}
}
void RedState::Deposit(double amount)
{
	this->balance += amount;
	StateCheck();
}

void RedState::Withdraw(double amount)
{
	cout << "透支状态，无法取款" << endl;
}

main.cpp

#include<iostream>
#include"Account.h"
#include"AccountState.h"
using namespace std;

int main() {
	Account* acc = new Account("gazikel", 2500);

	cout << "==========绿色状态存钱===========" << endl;
	acc->Deposit(1500);
	cout << "------------------------------" << endl;

	// 绿色状态取钱
	cout << "==========绿色状态取钱===========" << endl;
	acc->Withdraw(4500);
	cout << "------------------------------" << endl;
	// 黄色状态存钱
	cout << "==========黄色状态存钱===========" << endl;
	acc->Deposit(100);
	cout << "------------------------------" << endl;
	// 黄色状态取钱
	cout << "==========黄色状态取钱===========" << endl;
	acc->Withdraw(700);
	cout << "------------------------------" << endl;
	// 红色状态取钱
	cout << "==========红色状态取钱===========" << endl;
	acc->Withdraw(100);
	// 红色状态存钱
	cout << "==========红色状态存钱===========" << endl;
	acc->Deposit(1000);
}

---

Java

Account类：

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);
    }
}

AccountState抽象类：

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);
}

三个状态具体实现类

GreenState

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();
    }
}

RedState:

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！");
    }
}

YellowState

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();

    }
}