软件设计实验 22：状态模式
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；
GreenState.java:
public class GreenState extends AccountState{
public GreenState(double balance,Account acc) {
this.balance = balance;
this.account = acc;
this.stateName = "正常状态";
}
}
RedState.java:
public class RedState extends AccountState{
public RedState(AccountState state) {
this.balance = state.balance;
this.account = state.account;
this.stateName="透支状态";
}
public void withdraw(double amount) {
System.out.println(account.getOwner()+"取款"+amount);
System.out.println("抱歉，您的账户已处于透支状态，不能取款！");
}
}
YellowState:
public class YellowState extends AccountState{
public YellowState(AccountState state) {
this.balance = state.balance;
this.account = state.account;
this.stateName="欠费状态";
}
}
Account.java:
public class Account {
private AccountState state;
private String owner;
public AccountState getState() {
return state;
}
public void setState(AccountState state) {
this.state = state;
}
public String getOwner() {
return owner;
}
public void deposit(double amount) {
state.deposit(amount);
}
public void withdraw(double amount) {
state.withdraw(amount);
}
public Account(String owner, double initBalance) {
this.owner = owner;
this.state = new GreenState(initBalance,this);
System.out.println(this.owner + "开户成功！银行卡初始金额：" + initBalance);
System.out.println("----------------------------------------------------");
}
}
AccountState.java:
public abstract class AccountState {
protected Account account;//账户名
protected double balance;//账户金额
protected String stateName;//当前状态
public void deposit(double amount) {
System.out.println(account.getOwner() + "存款" + amount);
this.balance = this.balance + amount;
stateCheck();
System.out.println("账户余额：" + this.balance);
System.out.println("账户状态：" + account.getState().stateName);
}
public void withdraw(double amount) {
System.out.println(account.getOwner() + "取款" + amount);
this.balance = this.balance - amount;
stateCheck();
System.out.println("账户余额：" + this.balance);
System.out.println("账户状态：" + account.getState().stateName);
}
public void stateCheck(){//状态审查
if( balance >= -1000 && balance < 0 ) {
account.setState(new YellowState(this));
}else if( balance < -1000 ) {
account.setState(new RedState(this));
}else if ( balance > 0 ){
account.setState(new GreenState(this.balance,this.account));
}
}
}
Client.java:
public class Client {
public static void main(String[] args) {
Account account = new Account("张三",100);
account.deposit(8888);
System.out.println("------------------------------");
account.withdraw(666);
System.out.println("------------------------------");
account.deposit(50);
System.out.println("------------------------------");
account.withdraw(9000);
System.out.println("------------------------------");
account.withdraw(50000);
System.out.println("------------------------------");
account.deposit(3000);
System.out.println("------------------------------");
account.withdraw(100);
}
}
