状态模式

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。
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;
}
public void deposit(double amount) {
state.deposit(amount);
System.out.println("现金余额为" + this.state.balance);
}

public void withdraw(double amount){
state.withdraw(amount);
System.out.println("现金余额为" + state.balance);
}
}
package com.gazikel;
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();

}
}