每日博客

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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。

C++版

#include<iostream>
using namespace std;
class Account;
class AccountState {
public:
Account *acc;
double balance;
public:
virtual void stateCheck() = 0;
void deposit(double amount);
virtual void withdraw(double amount);
};
class Account {
private:
AccountState *state;
string owner;
public:
Account(string owner, double init);

void setState(AccountState *state) {
this->state = state;
}
AccountState* getState() {
return this->state;
}
string getOwner() {
return this->owner;
}
void deposit(double amount) {
state->deposit(amount);
}
void withdraw(double amount) {
state->withdraw(amount);
}
};
class RedState :public AccountState {
public:
RedState(AccountState *state) {
this->balance = state->balance;
this->acc = state->acc;
}
void stateCheck();
};
class YellowState :public AccountState {
public:
YellowState(AccountState *state) {
this->balance = state->balance;
this->acc = state->acc;
}
void stateCheck();
};
class GreenState :public AccountState {
public:
GreenState(double balance, Account *acc) {
this->balance = balance;
this->acc = acc;
}
GreenState(AccountState *state) {
this->acc = state->acc;
this->balance = state->balance;
}
void stateCheck() {
if (balance >= -1000 && balance < 0) {
acc->setState(new YellowState(this));
}
else if (balance < -1000) {
acc->setState(new RedState(this));
}
else {
acc->setState(new GreenState(this));
}
}
};
void RedState::stateCheck() {
if (balance >= -1000 && balance < 0) {
acc->setState(new YellowState(this));
}
else if (balance < -1000) {
acc->setState(new RedState(this));
}
else {
acc->setState(new GreenState(this));
}
}
void YellowState::stateCheck() {
if (balance >= -1000 && balance < 0) {
acc->setState(new YellowState(this));
}
else if (balance < -1000) {
acc->setState(new RedState(this));
}
else {
acc->setState(new GreenState(this));
}
}
void AccountState::deposit(double amount) {
cout << "存款" << amount << endl;
this->balance += amount;
stateCheck();
cout << "账户余额：" << this->balance << endl;
}
void AccountState::withdraw(double amount) {
cout << "取款" << amount << endl;
if(amount> balance)cout << "您的账户余额不足，不能取款！" << endl;
else this->balance -= amount;
stateCheck();
cout << "账户余额：" << this->balance << endl;
}
Account::Account(string owner, double init) {
this->owner = owner;
this->state = new GreenState(init, this);
}
int main() {
Account *account = new Account("用户", 100);
account->deposit(100);
cout << "------------------------------" << endl;
account->withdraw(500);
cout << "------------------------------" << endl;
account->deposit(1000);
cout << "------------------------------" << endl;
account->withdraw(2000);
account->withdraw(100);
cout << "------------------------------" << endl;
account->deposit(2000);
cout << "------------------------------" << endl;
return 0;
}