C# 反射(Reflection)的用处分析


乱侃

       作为一名新手,一直没有勇气去写一篇分享。原因有很多:诸如:自己水平有限、语言表达不准确、写出的东西没有一点技术点被人嘲笑。今天在公司听了内部员工的一个分享,其中最重要的一点是:提升自身水平的最佳的途径就是——交流。不管你是通过什么途径,交流也好、整理成文字分享也好等等都是很好的方式。故此,今天献丑写一篇自己的心得分享,欢迎各路大神的指教!

   需求背景

     今天接到的需求里面有个这样的需求,如下图所示,需要打印出如Excel内容呈现的单据。

    动手操作第一版本

     而为了实现这个业务需要涉及三张表的数据。(存放单据的表、审核意见表、审核状态表)
     三张表的关系:单据表1:1审核状态表,单据表1:N审核意见表
     为了实现让View页面整洁,我定义了一个SpecialPrintModel类

public class SpecialPrintModel
  {
    /// <summary>
    /// 供应商承担
    /// </summary>
    public string SupplierUnderTaker { get; set; }

    /// <summary>
    /// 客户订单号
    /// </summary>
    public string CustomerSerialNumber { get; set; }
    
    /// <summary>
    /// 付款金额
    /// </summary>
    public decimal PayAmount { get; set; }

    /// <summary>
    /// 开户行
    /// </summary>
    public string OpeningBank { get; set; }

    /// <summary>
    /// 收款单位
    /// </summary>
    public string CollectionMonad { get; set; }

    /// <summary>
    /// 银行帐号
    /// </summary>
    public string BankAccount { get; set; }

    /// <summary>
    /// 经办人
    /// </summary>
    public string ResponseiblePerson { get; set; }

    /// <summary>
    /// 分管领导
    /// </summary>
    public string Leader { get; set; }

    /// <summary>
    /// 财务审核
    /// </summary>
    public string FinanceApproval { get; set; }

    /// <summary>
    /// 财务经理审核
    /// </summary>
    public string FinanceManagerApproval { get; set; }

    /// <summary>
    /// 财务总监审核
    /// </summary>
    public string FinanceDirectorApproval { get; set; }

    /// <summary>
    /// CEO审核
    /// </summary>
    public string CEOApproval { get; set; }

    /// <summary>
    /// 流水号
    /// </summary>
    public string SerialNumber { get; set; }
  }
public List<ShipSpecialPrintModel> GetTobePaidRecepit(ShipSpecialSearch search)
 {
   List<ShipSpecialPrintModel> curiseShipModel = new List<ShipSpecialPrintModel>();
   var toBePaidModel = persistant.GetTobePaidRecepit(search);//查找出待支付的单据表信息
   ArrayList serialArray=new ArrayList();//定义一个流水号列表
   toBePaidModel.ForEach((u) => { serialArr.Add(u.SerialNumber); });
   var toBePaidComment = persistant.GetTobePaidRecepitComment(serialArr);//查找出待支付单据的审核意见表(1个单据对应多少审核意见)
   foreach (var item in toBePaidModel)
   {
     ShipSpecialPrintModel temp = new ShipSpecialPrintModel()
     {
         SupplierUnderTaker = supplierUnderTaker;
         CustomerSerialNumber = item.CustomerOrderNumber;
         PayAmount = item.PayAmount;
         OpeningBank = item.PayBank;
         CollectionMonad = item.Payee;
         ResponseiblePerson = item.Creator;
         SerialNumber = item.SerialNumber;
     };
     curiseShipModel.Add(temp);
   }
    foreach (var curise in curiseShipModel)
      {
        foreach (var comment in toBePaidComment)
        {
          if (comment.SerialNumber == curise.SerialNumber)
          {
            if (comment.ApprovalLevel == (int)LevelType.BranchedLeader)
            {
              curise.Leader = comment.Creator;
            }
            else if (comment.ApprovalLevel == (int)LevelType.Finance)
            {
              curise.FinanceApproval = comment.Creator;
            }
            else if (comment.ApprovalLevel == (int)LevelType.FinanceManager)
            {
              curise.FinanceManagerApproval = comment.Creator;
            }
            else if (comment.ApprovalLevel == (int)LevelType.ProjectDirector)
            {
              curise.FinanceDirectorApproval = comment.Creator;
            }
            else if (comment.ApprovalLevel == (int)LevelType.CEO)
            {
              curise.CEOApproval = comment.Creator;
            }
          }
        }
      }

   return curiseShipModel
 }

    呵呵,上面的代码基本完成了业务的需求,可是如果业务需要打印出CTO的名称、CIO的名称那在if else这边加,虽然很简单但是违背了开放-封闭的原则。故本人决定用反射去完成这if...else的事情。
因为if...else里面的判断是当前的这笔单据的审核意见表的层级是不是跟SpecialPrintModel的字段所对应的层级相等,若相等则在对应字段写入相对应的名称。决定把SpecialPrintModel这个类修改下。
 
   动手操作第二版本

public class ShipSpecialPrintModel
  {
    /// <summary>
    /// 供应商承担
    /// </summary>
    public string SupplierUnderTaker { get; set; }

    /// <summary>
    /// 客户订单号
    /// </summary>
    public string CustomerSerialNumber { get; set; }
    
    /// <summary>
    /// 付款金额
    /// </summary>
    public decimal PayAmount { get; set; }

    /// <summary>
    /// 开户行
    /// </summary>
    public string OpeningBank { get; set; }

    /// <summary>
    /// 收款单位
    /// </summary>
    public string CollectionMonad { get; set; }

    /// <summary>
    /// 银行帐号
    /// </summary>
    public string BankAccount { get; set; }

    /// <summary>
    /// 经办人
    /// </summary>
    public string ResponseiblePerson { get; set; }

    /// <summary>
    /// 分管领导
    /// </summary>
    [LevelAttribute(Level = 1)]
    public string Leader { get; set; }

    /// <summary>
    /// 财务审核
    /// </summary>
     [LevelAttribute(Level = 2)]
    public string FinanceApproval { get; set; }

    /// <summary>
    /// 财务经理审核
    /// </summary>
     [LevelAttribute(Level = 3)]
    public string FinanceManagerApproval { get; set; }

    /// <summary>
    /// 财务总监审核
    /// </summary>
     [LevelAttribute(Level = 4)]
    public string FinanceDirectorApproval { get; set; }

    /// <summary>
    /// CEO审核
    /// </summary>
     [LevelAttribute(Level = 5)]
    public string CEOApproval { get; set; }

    /// <summary>
    /// 流水号
    /// </summary>
    public string SerialNumber { get; set; }
  }

  public class LevelAttribute : Attribute
  {
    public int Level { get; set; }
  }
var toBePaidComment = persistant.GetTobePaidRecepitComment(ArrayList.Adapter(toBePaidModel.Select(u => u.SerialNumber).ToList()));
  var specialPropertyInfo = (from property in typeof(CuriseShipSpecialPrintModel).GetProperties()
                    where property.GetCustomAttributes(typeof(LevelAttribute), false).Count() > 0
                    select property).ToList();

 toBePaidModel.ForEach((item)=>{
    ShipSpecialPrintModel temp = new ShipSpecialPrintModel()
     {
         SupplierUnderTaker = supplierUnderTaker;
         CustomerSerialNumber = item.CustomerOrderNumber;
         PayAmount = item.PayAmount;
         OpeningBank = item.PayBank;
         CollectionMonad = item.Payee;
         ResponseiblePerson = item.Creator;
         SerialNumber = item.SerialNumber;
     };
    var thisComments=toBePaidComment.Where(u=>u.SerialNumber =item.SerialNumber ).ToList();
    thisComment.ForEach((cm)=>
    {
     if(cm.ApprovalLevel==(specialPropertyInfo.GetCustomAttributes(typeof(LevelAttribute),false).First() as LevelAttribute).Level)
     {
       cm.SetValue(model,cm.Creator,null);
     } 
    });
 })

    然而看到,propertyInfos那边基本上每循环一次都需要去反射查找下元素,为了避免这样的性能消耗,决定再修改一翻,定义一个字典去存储SpecialPrintModel标有特性类的字段。

   动手操作第三版本

Dictionary<int, PropertyInfo> dic = new Dictionary<int, PropertyInfo>();
  propertyInfos.ForEach((myProperty) => {      dic.Add((a.GetCustomAttributes(typeof(LevelAttribute),false).First() as LevelAttribute).Level,myProperty));
   } );

 comments.ForEach((cm) =>
          {
              if (dic.Keys.Contains(cm.ApprovalLevel))
              {
                dic[cm.ApprovalLevel].SetValue(model, cm.Creator, null);
              }
          });

   总体经过三次的修改,已经避免if...else的代码。这样而言,也比较适合后面比如再需要打印CTO审核的名称。那样只需要再Model类里面填写字段与在字段上加上个特效。

  总结

      就像我同事说的那样,做任务事情只要想想、多敲几次。一些问题就不是问题了。好了,今天就写到这里吧。晚安各位!

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