public class VirtualWallet { Domain领域模型(充血模型)private Long id;private Long cr
public class VirtualWallet { // Domain领域模型(充血模型)
private Long id;
private Long createTime = System.currentTimeMillis();;
private BigDecimal balance = BigDecimal.ZERO;
public VirtualWallet(Long preAllocatedId) {
this.id = preAllocatedId;
}
public BigDecimal balance() {
return this.balance;
}
public void debit(BigDecimal amount) {
if (this.balance.compareTo(amount) < 0) {
throw new InsufficientBalanceException(...);
}
this.balance.subtract(amount);
}
public void credit(BigDecimal amount) {
if (amount.compareTo(BigDecimal.ZERO) < 0) {
throw new InvalidAmountException(...);
}
this.balance.add(amount);
}
}
public class VirtualWalletService {
// 通过构造函数或者IOC框架注入
private VirtualWalletRepository walletRepo;
private VirtualWalletTransactionRepository transactionRepo;
public VirtualWallet getVirtualWallet(Long walletId) {
VirtualWalletEntity walletEntity = walletRepo.getWalletEntity(walletId);
VirtualWallet wallet = convert(walletEntity);
return wallet;
}
public BigDecimal getBalance(Long walletId) {
return walletRepo.getBalance(walletId);
}
public void debit(Long walletId, BigDecimal amount) {
VirtualWalletEntity walletEntity = walletRepo.getWalletEntity(walletId);
VirtualWallet wallet = convert(walletEntity);
wallet.debit(amount);
walletRepo.updateBalance(walletId, wallet.balance());
}
public void credit(Long walletId, BigDecimal amount) {
VirtualWalletEntity walletEntity = walletRepo.getWalletEntity(walletId);
VirtualWallet wallet = convert(walletEntity);
wallet.credit(amount);
walletRepo.updateBalance(walletId, wallet.balance());
}
public void transfer(Long fromWalletId, Long toWalletId, BigDecimal amount) {
//...跟基于贫血模型的传统开发模式的代码一样...
}
}
可以看到Domain中也实现了几个业务判定
整体在Service中也调用了domain中的几个方法
如果业务更加复杂
public class VirtualWallet {
private Long id;
private Long createTime = System.currentTimeMillis();;
private BigDecimal balance = BigDecimal.ZERO;
private boolean isAllowedOverdraft = true;
private BigDecimal overdraftAmount = BigDecimal.ZERO;
private BigDecimal frozenAmount = BigDecimal.ZERO;
public VirtualWallet(Long preAllocatedId) {
this.id = preAllocatedId;
}
public void freeze(BigDecimal amount) { ... }
public void unfreeze(BigDecimal amount) { ...}
public void increaseOverdraftAmount(BigDecimal amount) { ... }
public void decreaseOverdraftAmount(BigDecimal amount) { ... }
public void closeOverdraft() { ... }
public void openOverdraft() { ... }
public BigDecimal balance() {
return this.balance;
}
public BigDecimal getAvailableBalance() {
BigDecimal totalAvaliableBalance = this.balance.subtract(this.frozenAmount);
if (isAllowedOverdraft) {
totalAvaliableBalance += this.overdraftAmount;
}
return totalAvaliableBalance;
}
public void debit(BigDecimal amount) {
BigDecimal totalAvaliableBalance = getAvailableBalance();
if (totoalAvaliableBalance.compareTo(amount) < 0) {
throw new InsufficientBalanceException(...);
}
this.balance.subtract(amount);
}
public void credit(BigDecimal amount) {
if (amount.compareTo(BigDecimal.ZERO) < 0) {
throw new InvalidAmountException(...);
}
this.balance.add(amount);
}
}
更复杂的业务在Domain中得到解决，实际repo或dao还会在service中进行
Domain中保留独立性 与其他服务层解耦
