准备一个计时器，看需要多少分钟，才能说出下面这个函数做了哪些事？
public void work()
{
拿出碗;
拿出筷子;
摆碗;
摆筷子;
坐下;
拿起勺子;
盛汤;
喝汤;
while (还没吃饱)
{
盛饭;
夹菜;
张口;
咀嚼;
吞咽;
}
脱鞋子;
脱衣服;
脱裤子;
穿睡衣;
穿睡裤;
刷牙;
洗脸;
上床;
关灯;
躺下;
while (不困)
{
刷手机;
}
放下手机;
闭眼;
拿出棍子;
走到豆豆跟前;
敲打豆豆;
}
读的时候，是不是一万匹神兽飘过：你特么到底要干嘛？
好的，重构一下，下面的代码呢？又需要多少分钟？
public void work()
{
吃饭();
睡觉();
打豆豆();
}
为什么要重构？
面对遗留代码，一个团队花在「读代码」的时间，是「写代码」时间的 10 倍以上。
如果花 1 小时的时间重构一下代码，可以节省后续 n 小时的读代码时间，那么，重构不应该成为程序员的基本良心吗？
什么时候重构？
有句话说：如果不痛，就不要重构。
从来不需要去读的代码，就不需要去重构。
反过来说，若因为加功能或者其它任何原因，需要去读某一段代码，就应该对它进行重构。
你 3 分钟前写的代码，一定还需要去读它吧？那么，你应该重构你 3 分钟前写的代码。
这就是「重构不是吃饭，饿了才吃；重构是呼吸，随时随地」的道理。
如何开始重构？
都知道抽方法是最常见的重构手法之一，可是什么时候抽方法呢？
我建议的重构入门第一准则：所有的 Public 方法，由且只由 Private 方法组成。
如果上面的吃饭(); 睡觉(); 打豆豆(); 就是 3 个私有方法，对其适当地命名，让名字清晰表达它的意图。
如此，你不怎么需要写注释。
那些说注释越多越好的，可能，还没学会写代码。
生成代码实例
学习 TDD 也好，重构也好，一个很大的障碍，就是没办法把例子里学到的东西应用到生产代码中。
下面是我花了 1 小时重构的现实中原封不动的代码，比上面的傻瓜示例肯定更有挑战。
但是，使用上面的第一准则，已经足够让你开始踏上重构这条路了。
重构前：（麻烦您的鼠标了）
Public Function OutputVAT() As CN.ExportChinaVATInvoiceResponse
Dim resp As New CN.ExportChinaVATInvoiceResponse
Dim output As CN.ChinaVATInvoice = Nothing
'Dim outputList As New List(Of CN.ChinaVATInvoice)
Dim setting = New Xml.XmlWriterSettings
Dim sbSummary As New StringBuilder
'Dim saveChinaVATJob As SaveOutputChinaVATXMLToDisk = Nothing
Dim v As CN.Validation = Nothing
Dim bFileCreateSuccess As Boolean = False
Dim logs As New List(Of EISChinaVatLog)
Try
Dim firstReq As CN.ExportChinaVATInvoiceRequest
firstReq = _expRequests(0)
'PublishExportRequest()
resp.Validation = ValidateRequestForVATOutput()
Dim sw1 As New IO.StringWriter
Dim ser As New XmlSerializer(firstReq.GetType())
ser.Serialize(sw1, firstReq)
Dim requestString As String = sw1.ToString()
requestString = requestString.Replace("utf-16", "utf-8")
sw1.Close()
Dim logSrc As New ExportChinaVATDataSource
logSrc.InsertLogForChinaVATExport("Export China VAT Request",
firstReq.GFSVATGroupNumber,
requestString)
If resp.Validation IsNot Nothing AndAlso resp.Validation.HasErrors Then
Return resp
End If
setting.OmitXmlDeclaration = True
setting.Indent = True
setting.Encoding = New UTF8Encoding(False)
Dim writerSummary As Xml.XmlWriter = XmlTextWriter.Create(sbSummary, setting)
Init()
writerSummary.WriteStartDocument()
writerSummary.WriteStartElement("ChinaVATInvoices")
For Each req As CN.ExportChinaVATInvoiceRequest In _expRequests
writerSummary.WriteStartElement("ChinaVATInvoice")
writerSummary.WriteStartElement("VATInvoiceItems")
If req IsNot Nothing Then
If req.CustomerCode IsNot Nothing AndAlso req.CustomerCode.Trim.Length > 0 Then
GetCustomerinfo(req.CustomerCode, req)
End If
If req.CHRBranchCode IsNot Nothing AndAlso req.CHRBranchCode.Trim.Length > 0 Then
GetBranchInfo(req.CHRBranchCode, req)
End If
For Each invRate As CN.VATInvoiceItem In req.VATInvoiceItem
output = ConvertToChinaVATInvoice(invRate, req)
If output IsNot Nothing Then
writerSummary.WriteStartElement("VATInvoiceItem")
writerSummary.WriteStartElement("VATInvoiceType")
writerSummary.WriteValue(output.VATInvoiceType)
writerSummary.WriteEndElement()
writerSummary.WriteStartElement("GFSVATGroupNumber")
writerSummary.WriteValue(output.GFSVATGroupNumber)
writerSummary.WriteEndElement()
writerSummary.WriteStartElement("VATTaxinvoiceDate")
If req IsNot Nothing AndAlso req.VATTaxinvoiceDate <> Date.MinValue AndAlso
req.VATTaxinvoiceDate.ToString <> "1/1/0001 12:00:00 AM" Then
writerSummary.WriteValue(String.Format("{0}-{1}-{2}", req.VATTaxinvoiceDate.Year.ToString,
(req.VATTaxinvoiceDate.Month + 100).ToString.Substring(1, 2),
(req.VATTaxinvoiceDate.Day + 100).ToString.Substring(1, 2)))
End If
writerSummary.WriteEndElement()
writerSummary.WriteStartElement("CustomerNumber")
writerSummary.WriteValue(output.CustomerNumber)
writerSummary.WriteEndElement()
writerSummary.WriteStartElement("CustomerName")
writerSummary.WriteValue(output.CustomerName)
writerSummary.WriteEndElement()
writerSummary.WriteStartElement("CustomerTaxID")
writerSummary.WriteValue(output.CustomerTaxID)
writerSummary.WriteEndElement()
writerSummary.WriteStartElement("CustomerDetail")
writerSummary.WriteValue(String.Format("{0} {1}", output.CustomerAddress, output.CustomerTelephoneNumber))
writerSummary.WriteEndElement()
writerSummary.WriteStartElement("CustomerBankInfo")
writerSummary.WriteValue(String.Format("{0} {1}", output.CustomerBankName, output.CustomerBankAccountNumber))
writerSummary.WriteEndElement()
writerSummary.WriteStartElement("Remarks")
writerSummary.WriteValue(output.Remarks)
writerSummary.WriteEndElement()
writerSummary.WriteStartElement("GovernmentApprovalNumber")
writerSummary.WriteValue(output.GovernmentApprovalNumber)
writerSummary.WriteEndElement()
writerSummary.WriteStartElement("OriginalVATBatchID")
writerSummary.WriteValue(output.OriginalVATBatchID)
writerSummary.WriteEndElement()
writerSummary.WriteStartElement("OriginalVATInvoiceNumber")
writerSummary.WriteValue(output.OriginalVATInvoiceNumber)
writerSummary.WriteEndElement()
writerSummary.WriteStartElement("VATInvoiceBy")
writerSummary.WriteValue(output.VATInvoiceBy)
writerSummary.WriteEndElement()
writerSummary.WriteStartElement("VATApprovedBy")
writerSummary.WriteValue(output.VATApprovedBy)
writerSummary.WriteEndElement()
writerSummary.WriteStartElement("VATGroupedBy")
writerSummary.WriteValue(output.VATGroupedBy)
writerSummary.WriteEndElement()
writerSummary.WriteStartElement("CHRBranchBankInfo")
writerSummary.WriteValue(String.Format("{0} {1}", output.CHRBranchBankAccountName, output.CHRBranchBankAccountNumber))
writerSummary.WriteEndElement()
writerSummary.WriteStartElement("CHRBranchInfo")
writerSummary.WriteValue(String.Format("{0} {1}", output.CHRBranchAddress, output.CHRBranchTelephoneNumber))
writerSummary.WriteEndElement()
writerSummary.WriteStartElement("ItemNumber")
If output.CommodityItemNumber IsNot Nothing Then
writerSummary.WriteValue(output.CommodityItemNumber)
End If
writerSummary.WriteEndElement()
writerSummary.WriteStartElement("ChargeName")
writerSummary.WriteValue(output.ChargeName)
writerSummary.WriteEndElement()
writerSummary.WriteStartElement("ModelNumber")
If output.ModelNumber IsNot Nothing Then
writerSummary.WriteValue(output.ModelNumber)
End If
writerSummary.WriteEndElement()
writerSummary.WriteStartElement("ChargeBasis")
writerSummary.WriteValue(output.ChargeBasis)
writerSummary.WriteEndElement()
writerSummary.WriteStartElement("Quantity")
writerSummary.WriteValue(output.Quantity)
writerSummary.WriteEndElement()
writerSummary.WriteStartElement("Amount")
writerSummary.WriteValue(output.TotalInvoiceAmount)
writerSummary.WriteEndElement()
writerSummary.WriteStartElement("VATRate")
writerSummary.WriteValue(output.VATRate)
writerSummary.WriteEndElement()
writerSummary.WriteStartElement("VATAmount")
writerSummary.WriteValue(output.TaxAmount)
writerSummary.WriteEndElement()
writerSummary.WriteStartElement("DiscountAmount")
If output.DiscountAmount IsNot Nothing Then
writerSummary.WriteValue(output.DiscountAmount)
End If
writerSummary.WriteEndElement()
writerSummary.WriteStartElement("DiscountTaxAmount")
If output.DiscountTaxAmount IsNot Nothing Then
writerSummary.WriteValue(output.DiscountTaxAmount)
End If
writerSummary.WriteEndElement()
writerSummary.WriteEndElement()
'SaveBatchInfo(output)
End If
Next
writerSummary.WriteEndElement()
writerSummary.WriteEndElement()
End If
'Build Log if there were any warnings and user override those.
If (req.InvoiceWarnings IsNot Nothing) Then
For Each logReq In req.InvoiceWarnings
Dim invoiceNum As Long
If Long.TryParse(logReq.InvoiceNum, invoiceNum) Then
logs.Add(New EISChinaVatLog With {
.BatchID = req.BatchID,
.ChinaVatBatchID = req.ChinaVATBatchID,
.CreateDate = DateTime.Now,
.InvoiceNum = invoiceNum,
.UserId = req.SEVERLETTER,
.Operation = "WarningOverride",
.Notes = String.Join(",", logReq.Notes)})
End If
Next
End If
Next
writerSummary.WriteEndElement()
writerSummary.WriteEndDocument()
writerSummary.Flush()
writerSummary.Close()
'Debug.Print(sbSummary.ToString)
Dim mediator As EDIExport.ISendChinaVATService = EDIExport.SendChinaVATFactory.GetSendChinaVATService
mediator.SetSendParamenter(firstReq.GFSVATGroupNumber, sbSummary.ToString, firstReq.CHRBranchCode, firstReq.VATGroupedBy)
' Attempt to create the VAT file.
bFileCreateSuccess = mediator.Send()
If bFileCreateSuccess Then
For Each log In logs
EnterpriseInvoiceDAO.InsertEISChinaVatLog(log)
Next
End If
logSrc.InsertLogForChinaVATExport("Export China VAT Resp",
output.GFSVATGroupNumber,
sbSummary.ToString)
Catch ex As Exception
ExceptionManager.Publish(ex)
End Try
If resp.Validation Is Nothing OrElse bFileCreateSuccess = False Then
If resp.Validation Is Nothing Then
resp.Validation = New CN.Validation(False, False, Nothing, Nothing)
Dim vrList As New List(Of CN.ValidationResult)
vrList.Add(New CN.ValidationResult With {.Text = "Failed to create VAT file."})
resp.Validation.Errors = vrList
resp.Validation.HasErrors = True
Else
If resp.Validation.Errors Is Nothing Then
resp.Validation.Errors = New List(Of CN.ValidationResult)
resp.Validation.Errors.Add(New CN.ValidationResult With {.Text = "Failed to create VAT file."})
resp.Validation.HasErrors = True
Else
resp.Validation.Errors.Add(New CN.ValidationResult With {.Text = "Failed to create VAT file."})
resp.Validation.HasErrors = True
End If
End If
End If
Return resp
End Function
重构后：
Public Function ExportVATInvoice() As ExportChinaVATInvoiceResponse
LogRequest()
Dim resp As New ExportChinaVATInvoiceResponse With {
.Validation = ValidateRequest()
}
If resp.Validation.HasErrors Then
Return resp
End If
Dim xml = BuildXml()
Dim fileCreateSucceeded = TryCreateVATFile(xml)
If fileCreateSucceeded Then
LogWarnings()
End If
LogResponse(xml)
If fileCreateSucceeded = False Then
AddErrorsToResponse(resp)
End If
Return resp
End Function
不知道谁说的（有人说是我说的）:
程序员看到很长的代码，应该像屎壳郎看到屎一样，兴奋地扑上去。
烂代码有个绰号，叫「屎山」。沧浪之水浊兮可以濯吾足，化身屎壳郎，为人民服务，也挺光荣的。
文档信息
- 本文作者：蔡建斌
- 本文链接：https://johncai.github.io/2020/07/01/refactor-long-methods/
- 版权声明：自由转载-非商用-非衍生-保持署名（创意共享3.0许可证）