"代码微变，质变！优雅编程的炼金术"

原创同城研发加文雄京东零售技术

一、需求开发修改代码

一次需求开发时碰到如下所示方法代码：

private OrderShoudSettlementAmount getOrderShoudSettlementAmount(OrderDTO orderMain, List<SettlementDetail> details) {    OrderShoudSettlementAmount settlementAmount = new OrderShoudSettlementAmount();    // 应结金额=33021-33002-32003+32001-31001    // 货款佣金=33005+33002+32003+31001    long feeMoney33021 = 0;    long feeMoney33002 = 0;    long feeMoney32003 = 0;    long feeMoney32001 = 0;    long feeMoney31001 = 0;    long feeMoney33005 = 0;    for (SettlementDetail settlementDetail : details) {        if (settlementDetail.getExpenseType().equals(FeeInfoEnum.FEE_INFO_FREIGHT_ZS_NOSETTLE.getVal())) {            feeMoney33021 += settlementDetail.getOassMoney();        }        if (settlementDetail.getExpenseType().equals(FeeInfoEnum.FEE_INFO_FREIGHT_YJ_ZS_NOSETTLE.getVal())) {            feeMoney33002 += settlementDetail.getOassMoney();        }        if (settlementDetail.getExpenseType().equals(FeeInfoEnum.FEE_INFO_GOODS_YJ_WJTZ.getVal())) {            feeMoney32003 += settlementDetail.getOassMoney();        }        if (settlementDetail.getExpenseType().equals(FeeInfoEnum.FEE_INFO_GOODS_NOSETTLE.getVal())) {            feeMoney32001 += settlementDetail.getOassMoney();        }        if (settlementDetail.getExpenseType().equals(FeeInfoEnum.FEE_INFO_BDYJ_YJ_NOSETTLE.getVal())) {            feeMoney31001 += settlementDetail.getOassMoney();        }        if (settlementDetail.getExpenseType().equals(FeeInfoEnum.FEE_INFO_YFYJ_ZS_XSG.getVal())) {            feeMoney33005 += settlementDetail.getOassMoney();        }    }    long settlementMoney = feeMoney33021 - feeMoney33002 - feeMoney32003 + feeMoney32001 - feeMoney31001;    long goodCommissionMoney = feeMoney33005 + feeMoney33002 + feeMoney32003 + feeMoney31001;    settlementAmount.setSettlementAmount(settlementMoney);    settlementAmount.setGoodsCommission(goodCommissionMoney);    settlementAmount.setOrderId(orderMain.getOrderId());    settlementAmount.setOrgCode(orderMain.getOrgCode());    settlementAmount.setStationNo(String.valueOf(orderMain.getDeliveryStationNo()));    settlementAmount.setBillTime(new Date());    settlementAmount.setRetSuccess(false);    return settlementAmount;}

该方法逻辑比较简单，就是组装OrderShoudSettlementAmount对象。其中需要计算2个金额，分别是settlementMoney和goodCommissionMoney。

本次需求新增了费项，需要修改该方法。代码修改后如下所示：

private OrderShoudSettlementAmount getOrderShoudSettlementAmount(OrderDTO orderMain, List<SettlementDetail> details) {    OrderShoudSettlementAmount settlementAmount = new OrderShoudSettlementAmount();    // 应结金额=33021-33002-32003+32001-31001+34012-34013    // 货款佣金=33005+33002+32003+31001+34013    long feeMoney33021 = 0;    long feeMoney33002 = 0;    long feeMoney32003 = 0;    long feeMoney32001 = 0;    long feeMoney31001 = 0;    long feeMoney33005 = 0;    // 本次需求新增费项    long feeMoney34012 = 0;    // 本次需求新增费项    long feeMoney34013 = 0;    for (SettlementDetail settlementDetail : details) {        if (settlementDetail.getExpenseType().equals(FeeInfoEnum.FEE_INFO_FREIGHT_ZS_NOSETTLE.getVal())) {            feeMoney33021 += settlementDetail.getOassMoney();        }        if (settlementDetail.getExpenseType().equals(FeeInfoEnum.FEE_INFO_FREIGHT_YJ_ZS_NOSETTLE.getVal())) {            feeMoney33002 += settlementDetail.getOassMoney();        }        if (settlementDetail.getExpenseType().equals(FeeInfoEnum.FEE_INFO_GOODS_YJ_WJTZ.getVal())) {            feeMoney32003 += settlementDetail.getOassMoney();        }        if (settlementDetail.getExpenseType().equals(FeeInfoEnum.FEE_INFO_GOODS_NOSETTLE.getVal())) {            feeMoney32001 += settlementDetail.getOassMoney();        }        if (settlementDetail.getExpenseType().equals(FeeInfoEnum.FEE_INFO_BDYJ_YJ_NOSETTLE.getVal())) {            feeMoney31001 += settlementDetail.getOassMoney();        }        if (settlementDetail.getExpenseType().equals(FeeInfoEnum.FEE_INFO_YFYJ_ZS_XSG.getVal())) {            feeMoney33005 += settlementDetail.getOassMoney();        }        // 本次需求新增费项        if (settlementDetail.getExpenseType().equals(FeeInfoEnum.FEE_INFO_CHF_XSG_NOSETTLE.getVal())) {            feeMoney34012 += settlementDetail.getOassMoney();        }        // 本次需求新增费项        if (settlementDetail.getExpenseType().equals(FeeInfoEnum.FEE_INFO_CHF_YJ_XSG.getVal())) {            feeMoney34013 += settlementDetail.getOassMoney();        }    }    // 本次需求新增费项追加计算 + feeMoney34012 - feeMoney34013    long settlementMoney = feeMoney33021 - feeMoney33002 - feeMoney32003 + feeMoney32001 - feeMoney31001 + feeMoney34012 - feeMoney34013;    // 本次需求新增费项追加计算 + feeMoney34013    long goodCommissionMoney = feeMoney33005 + feeMoney33002 + feeMoney32003 + feeMoney31001 + feeMoney34013;    settlementAmount.setSettlementAmount(settlementMoney);    settlementAmount.setGoodsCommission(goodCommissionMoney);    settlementAmount.setOrderId(orderMain.getOrderId());    settlementAmount.setOrgCode(orderMain.getOrgCode());    settlementAmount.setStationNo(String.valueOf(orderMain.getDeliveryStationNo()));    settlementAmount.setBillTime(new Date());    settlementAmount.setRetSuccess(false);    return settlementAmount;}

二、嗅出代码的坏味道

Martin Fowler在《重构：改善既有代码的设计》一书中列出了22种代码的坏味道：

Duplicated Code（重复的代码）
Long Method（过长函数）
Large Class（过大类）
Long Parameter List（过长参数列）
Divergent Change（发散式变化）
Shotgun Surgery（霰弹式修改）
Feature Envy（依恋情结）
Data Clumps（数据泥团）
Primitive Obsession（基本型别偏执）
Switch Statements（switch惊悚现身）
Parallel Inheritance Hierarchies（平行继承体系
Lazy Class（冗赘类）
Speculative Generality（夸夸其谈未来性）
Temporary Field（令人迷惑的暂时字段）
Message Chains（过度耦合的消息链）
Middle Man（中间人）
Inappropriate Intimacy（狎昵关系）
Alternative Classes with Different Interfaces（异曲同工的类）
Incomplete Library Class（不完美的程序库类）
Data Class（纯稚的数据类）
Refused Bequest（被拒绝的遗贈）
Comments（过多的注释）

参照这22种代码的坏味道，我在以上方法代码中嗅出了2种代码的坏味道：

【坏味道1：Duplicated Code（重复的代码）】

for循环中对每种费项的累加操作是重复代码，而且每次新增费项，还得不断增加该重复操作。

for (SettlementDetail settlementDetail : details) {    if (settlementDetail.getExpenseType().equals(FeeInfoEnum.FEE_INFO_FREIGHT_ZS_NOSETTLE.getVal())) {        feeMoney33021 += settlementDetail.getOassMoney();    }    if (settlementDetail.getExpenseType().equals(FeeInfoEnum.FEE_INFO_FREIGHT_YJ_ZS_NOSETTLE.getVal())) {        feeMoney33002 += settlementDetail.getOassMoney();    }    if (settlementDetail.getExpenseType().equals(FeeInfoEnum.FEE_INFO_GOODS_YJ_WJTZ.getVal())) {        feeMoney32003 += settlementDetail.getOassMoney();    }    if (settlementDetail.getExpenseType().equals(FeeInfoEnum.FEE_INFO_GOODS_NOSETTLE.getVal())) {        feeMoney32001 += settlementDetail.getOassMoney();    }    if (settlementDetail.getExpenseType().equals(FeeInfoEnum.FEE_INFO_BDYJ_YJ_NOSETTLE.getVal())) {        feeMoney31001 += settlementDetail.getOassMoney();    }    if (settlementDetail.getExpenseType().equals(FeeInfoEnum.FEE_INFO_YFYJ_ZS_XSG.getVal())) {        feeMoney33005 += settlementDetail.getOassMoney();    }    // 本次需求新增费项    if (settlementDetail.getExpenseType().equals(FeeInfoEnum.FEE_INFO_CHF_XSG_NOSETTLE.getVal())) {        feeMoney34012 += settlementDetail.getOassMoney();    }    // 本次需求新增费项    if (settlementDetail.getExpenseType().equals(FeeInfoEnum.FEE_INFO_CHF_YJ_XSG.getVal())) {        feeMoney34013 += settlementDetail.getOassMoney();    }}

【坏味道2：Divergent Change（发散式变化）】

Martin Fowler在书中对该坏味道的部分解释如下：

“我们希望软件能够更容易被修改——毕竟软件再怎么说本来就该是“软”的。一旦需要修改，我们希望能够跳到系统的某一点，只在该处做修改。”

现在该方法代码因为新需求开发，修改多处。

其实，除了以上2种代码的坏味道之外，该方法代码最大的问题是面向过程式编码而不是面向对象式的。

为什么这么说呢？

前面提到过该方法的主要作用是组装OrderShoudSettlementAmount对象，那么其逻辑就应该主要体现“组装”，而不是计算金额。计算金额相关逻辑应该抽离到单独的类中，这样既符合面向对象编程思想，也能够消除坏味道2。

三、重构代码

针对前面嗅出的代码坏味道，果断进行重构。重构之后代码如下所示：

private OrderShoudSettlementAmount getOrderShoudSettlementAmount(OrderDTO orderMain, List<SettlementDetail> details) {    OrderShoudSettlementAmount settlementAmount = new OrderShoudSettlementAmount();        Map<Integer, Long> expenseTypeToFeeMoneyMap = Maps.newHashMap();    for (SettlementDetail settlementDetail : details) {        long feeMoney = Optional.ofNullable(expenseTypeToFeeMoneyMap.get(settlementDetail.getExpenseType())).orElse(0L);        feeMoney += Optional.ofNullable(settlementDetail.getOassMoney()).orElse(0L);        expenseTypeToFeeMoneyMap.put(settlementDetail.getExpenseType(), feeMoney);    }    long settlementMoney = SettlementMoneyCalcFeeInfoEnum.calcSettlementMoney(expenseTypeToFeeMoneyMap);    long goodCommissionMoney = GoodCommissionMoneyCalcFeeInfoEnum.calcGoodCommissionMoney(expenseTypeToFeeMoneyMap);    settlementAmount.setSettlementAmount(settlementMoney);    settlementAmount.setGoodsCommission(goodCommissionMoney);    settlementAmount.setOrderId(orderMain.getOrderId());    settlementAmount.setOrgCode(orderMain.getOrgCode());    settlementAmount.setStationNo(String.valueOf(orderMain.getDeliveryStationNo()));    settlementAmount.setBillTime(new Date());    settlementAmount.setRetSuccess(false);    return settlementAmount;}

enum SettlementMoneyCalcFeeInfoEnum {    /**计算项*/    FEE_33021(FeeInfoEnum.FEE_INFO_FREIGHT_ZS_NOSETTLE, "+"),    FEE_33002(FeeInfoEnum.FEE_INFO_FREIGHT_YJ_ZS_NOSETTLE, "-"),    FEE_32003(FeeInfoEnum.FEE_INFO_GOODS_YJ_WJTZ, "-"),    FEE_32001(FeeInfoEnum.FEE_INFO_GOODS_NOSETTLE, "+"),    FEE_31001(FeeInfoEnum.FEE_INFO_BDYJ_YJ_NOSETTLE, "-"),    FEE_34012(FeeInfoEnum.FEE_INFO_CHF_XSG_NOSETTLE, "+"),    FEE_34013(FeeInfoEnum.FEE_INFO_CHF_YJ_XSG, "-");
    private final FeeInfoEnum feeInfoEnum;    private final String symbol;
    SettlementMoneyCalcFeeInfoEnum(FeeInfoEnum feeInfoEnum, String symbol) {        this.feeInfoEnum = feeInfoEnum;        this.symbol = symbol;    }        public static long calcSettlementMoney(Map<Integer, Long> expenseTypeToFeeMoneyMap) {        // 应结金额=33021-33002-32003+32001-31001+34012-34013        long settlementMoney = 0L;        for (SettlementMoneyCalcFeeInfoEnum calcFeeInfoEnum : SettlementMoneyCalcFeeInfoEnum.values()) {            if ("+".equals(calcFeeInfoEnum.symbol)) {                settlementMoney += Optional                        .ofNullable(expenseTypeToFeeMoneyMap.get(calcFeeInfoEnum.feeInfoEnum.getVal()))                        .orElse(0L);            }            if ("-".equals(calcFeeInfoEnum.symbol)) {                settlementMoney -= Optional                        .ofNullable(expenseTypeToFeeMoneyMap.get(calcFeeInfoEnum.feeInfoEnum.getVal()))                        .orElse(0L);            }        }        return settlementMoney;    }}

enum GoodCommissionMoneyCalcFeeInfoEnum {    /**计算项*/    FEE_33005(FeeInfoEnum.FEE_INFO_YFYJ_ZS_XSG),    FEE_33002(FeeInfoEnum.FEE_INFO_FREIGHT_YJ_ZS_NOSETTLE),    FEE_32003(FeeInfoEnum.FEE_INFO_GOODS_YJ_WJTZ),    FEE_31001(FeeInfoEnum.FEE_INFO_BDYJ_YJ_NOSETTLE),    FEE_34013(FeeInfoEnum.FEE_INFO_CHF_YJ_XSG);
    private final FeeInfoEnum feeInfoEnum;
    GoodCommissionMoneyCalcFeeInfoEnum(FeeInfoEnum feeInfoEnum) {        this.feeInfoEnum = feeInfoEnum;    }
    public static long calcGoodCommissionMoney(Map<Integer, Long> expenseTypeToFeeMoneyMap) {        // 货款佣金=33005+33002+32003+31001+34013        long goodCommissionMoney = 0L;        for (GoodCommissionMoneyCalcFeeInfoEnum calcFeeInfoEnum : GoodCommissionMoneyCalcFeeInfoEnum.values()) {            goodCommissionMoney += Optional                    .ofNullable(expenseTypeToFeeMoneyMap.get(calcFeeInfoEnum.feeInfoEnum.getVal()))                    .orElse(0L);        }        return goodCommissionMoney;    }}

四、总结

以上重构的方法代码比较简单，有些人可能会觉得不重构也挺好的，代码可读性也不差，每次修改也就肉眼可见的几个地方，没必要在这上面花费时间。

如果你有以上想法，不妨了解下软件工程中的“破窗效应”：

破窗效应指的是在软件开发过程中，如果存在低质量的代码或设计，如果不及时修复，就会导致其他开发人员也采用同样的低质量方案。这会逐渐升级到更严重的问题，导致软件系统变得难以维护、扩展和改进。因此，在软件开发中，及时解决问题和保持代码质量非常重要，以避免破窗效应对于整个项目造成的负面影响。

同时看看Martin Fowler在《重构：改善既有代码的设计》一书中对重构的部分解释：

重构的每个步骤都很简单，甚至显得有些过于简单：你只需要把某个字段从一个类移到另一个类，把某些代码从一个函数拉出来构成另一个函数，或是在继承体系中把某些代码推上推下就行了。但是，聚沙成塔，这些小小的修改累积起来就可以根本改善设计质量。

重构不仅能够提高代码质量，让代码优雅起来，同时也能让我们学以致用。我们所学的设计思想、原则、模式等理论知识，往往在重构中能够真正实践。

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