问题描述：
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。
Java源代码：
1 //Account.java 2 package shiyan22; 3 /** 4 * @Description：环境类 5 * @author 张紫诺 6 * 7 */ 8 public class Account { 9 private AccountState state; 10 private String name; 11 public Account(String name){ 12 this.name=name; 13 state=new Greenstate(this); 14 System.out.println(name+"开户成功！初始金额：0元"); 15 System.out.println("******************************"); 16 } 17 public void setState(AccountState state){ 18 this.state=state; 19 } 20 public AccountState getState() { 21 return this.state; 22 } 23 24 public String getName() { 25 return name; 26 } 27 public void setName(String name) { 28 this.name = name; 29 } 30 public void deposit(double money){ 31 state.deposit(money); 32 } 33 public void withdraw(double money){ 34 state.withdraw(money); 35 } 36 } 37 //AccountState.java 38 package shiyan22; 39 /** 40 * @Description：抽象状态类 41 * @author 张紫诺 42 * 43 */ 44 public abstract class AccountState { 45 protected Account acc; 46 protected double balance; 47 protected String stateName; 48 public abstract void stateCheck(double balance); 49 public double getBalance() { 50 return balance; 51 } 52 public void setBalance(double balance) { 53 this.balance = balance; 54 } 55 public String getStateName() { 56 return stateName; 57 } 58 public void setStateName(String stateName) { 59 this.stateName = stateName; 60 } 61 public void deposit(double amount) { 62 System.out.println(acc.getName()+"存款"+amount+"元"); 63 balance+=amount; 64 stateCheck(balance); 65 System.out.println("当前余额："+balance+"元，当前状态："+acc.getState().stateName); 66 } 67 public void withdraw(double amount) { 68 System.out.println(acc.getName()+"取款"+amount+"元"); 69 balance-=amount; 70 stateCheck(balance); 71 System.out.println("当前余额："+balance+"元，当前状态："+acc.getState().stateName); 72 } 73 } 74 //Greenstate.java 75 package shiyan22; 76 /** 77 * @Description：正常状态类 78 * @author 张紫诺 79 * 80 */ 81 public class Greenstate extends AccountState{ 82 public Greenstate(AccountState state){ 83 this.acc=state.acc; 84 this.balance=state.balance; 85 this.stateName="正常状态"; 86 } 87 public Greenstate(Account acc){ 88 this.balance=0; 89 this.acc=acc; 90 this.stateName="正常状态"; 91 } 92 public void stateCheck(double balance){ 93 if(balance<-1000){ 94 acc.setState(new Redstate(this)); 95 }else if(balance>=-1000&&balance<0){ 96 acc.setState(new Yellowstate(this)); 97 } 98 } 99 } 100 //Redstate.java 101 package shiyan22; 102 /** 103 * @Description：透支状态类 104 * @author 张紫诺 105 * 106 */ 107 public class Redstate extends AccountState { 108 109 public Redstate(AccountState state) { 110 this.acc=state.acc; 111 this.balance=state.getBalance(); 112 this.stateName="透支状态"; 113 } 114 115 public void stateCheck(double balance) { 116 if(balance >= -1000 && balance < 0){ 117 acc.setState(new Yellowstate(this)); 118 }else if(balance >= 0){ 119 acc.setState(new Greenstate(this)); 120 } 121 } 122 public void withdraw(double amount) { 123 System.out.println("对不起，"+acc.getName()+",您不能取款"); 124 System.out.println("当前余额："+balance+"元，当前状态："+acc.getState().stateName); 125 } 126 } 127 //Yellowstate.java 128 package shiyan22; 129 /** 130 * @Description：欠费状态类 131 * @author 张紫诺 132 * 133 */ 134 public class Yellowstate extends AccountState { 135 136 public Yellowstate(AccountState state) { 137 this.acc=state.acc; 138 this.balance=state.getBalance(); 139 this.stateName="欠费状态"; 140 } 141 142 public void stateCheck(double balance) { 143 if(balance >=0 ){ 144 acc.setState(new Greenstate(this)); 145 }else if(balance < -1000){ 146 acc.setState(new Redstate(this)); 147 } 148 } 149 } 150 //Client.java 151 package shiyan22; 152 public class Client { 153 public static void main(String args[]){ 154 Account acc=new Account("张三"); 155 acc.deposit(2000); 156 System.out.println("---------------------------------------"); 157 acc.withdraw(500); 158 System.out.println("---------------------------------------"); 159 acc.withdraw(2000); 160 System.out.println("---------------------------------------"); 161 acc.withdraw(600); 162 System.out.println("---------------------------------------"); 163 acc.withdraw(200); 164 } 165 }
运行结果：
