企业中台化落地：从战略分析到战术实践及架构演进过程

public interface WalletService {
    void done();
}

public class ConsumeService extends DefaultService {
    public ConsumeService(Wallet wallet, BigDecimal tradeAmount) {
        super(TradeRecord.builder().wallet(wallet).tradeAmount(tradeAmount).build());
    }
}

public interface Behavior {
    void doAction();
    InOutFlag getInOutFlag();
}

public class CreditBehavior extends DefaultBehavior {
    private final BigDecimal tradeAmount;

    public CreditBehavior(Wallet wallet, BigDecimal tradeAmount) {
        super(wallet);
        this.tradeAmount = tradeAmount;
    }

    @Override
    public void doAction() {
        super.doAction();
        wallet.setBalance(wallet.getBalance().add(tradeAmount));
    }

    @Override
    public InOutFlag getInOutFlag() {
        return InOutFlag.IN;
    }
}

public interface CheckPolicy {
    void check();
}

public class NoOverdraftAllowed implements CheckPolicy {
    private final Wallet wallet;
    private final BigDecimal tradeAmount;

    public NoOverdraftAllowed(Wallet wallet, BigDecimal tradeAmount) {
        this.wallet = wallet;
        this.tradeAmount = tradeAmount;
    }

    @Override
    public void check() {
        if (wallet.getBalance().compareTo(tradeAmount) < 0){
            throw new BizException("余额不足");
        }
    }
}

public abstract class DefaultService implements WalletService {

    protected abstract static class TradeConfig {
        public abstract TradeType tradeType();
        public abstract Behavior behavior();
        public abstract List<CheckPolicy> checkPolicies();
    }

    protected abstract TradeConfig tradeConfig();

    @Override
    public void done() {
        check();
        tradeConfig().behavior().doAction();
        tradeRecord.setBalance(tradeRecord.getWallet().getBalance());
        tradeRecord.setTradeStatus(TradeStatus.SUCCEED);
    }
}

public class LockService extends DefaultService {

    public LockService(Wallet wallet) {
        super(TradeRecord.builder().wallet(wallet).build());
    }

    @Override
    protected TradeConfig tradeConfig() {
        return new TradeConfig() {
            @Override
            public TradeType tradeType() {
                return TradeType.LOCK;
            }

            @Override
            public Behavior behavior() {
                return new LockBehavior(getWallet());
            }

            @Override
            public List<CheckPolicy> checkPolicies() {
                return CheckPolicyBuilder.builder()
                        .add(new NoAvailableStatusAllowed(getWallet()))
                        .build();
            }
        };
    }
}

public class RechargeRollbackService extends DefaultService {
    private final TradeRecord sourceTrade;

    public RechargeRollbackService(TradeRecord sourceTrade) {
        // ...
    }

    @Override
    protected DefaultService.TradeConfig tradeConfig() {
        return new TradeConfig() {
            @Override
            public TradeType tradeType() {
                return TradeType.RECHARGE_ROLLBACK;
            }

            @Override
            public Behavior behavior() {
                return new DebitBehavior(getWallet(), getTradeAmount());
            }

            @Override
            public List<CheckPolicy> checkPolicies() {
                return CheckPolicyBuilder.builder()
                        .add(new NoRechargeTypeAllowed(sourceTrade))
                        .add(new NoTimeoutAllowed(sourceTrade))
                        .add(new NoOverdraftAllowed(getWallet(), getTradeAmount()))
                        .add(new NoAvailableStatusAllowed(getWallet()))
                        .build();
            }
        };
    }
}

public abstract class DefaultTowPCService extends DefaultService implements TwoPCWalletService {

    public DefaultTowPCService(TradeRecord tradeRecord) {
        super(tradeRecord);
    }

    @Override
    public void process() {
        check();
        getTradeRecord().setTradeStatus(TradeStatus.PROCESSING);
    }
}

public class RechargeService extends DefaultTowPCService {
    public RechargeService(Wallet wallet, BigDecimal tradeAmount){
        super(TradeRecord.builder().wallet(wallet).tradeAmount(tradeAmount).build());
    }
}