背景

在企业应用中单据编号的自定义是一个很常见的需求，能不能抽象一个通用的框架呢？之前写个一篇的博文，感觉他们两个思路应该很相似。就让我们试试吧。

思路

这里的难点在于实现"解释器"，比如将"前缀_<日期:yyyy_MM_dd>"解释为“工号生成器”，而且“解释器”的“规则”允许动态增加。

 

实现

类图

核心代码

CodeRuleGenerator.cs

1 using System; 2 using System.Collections.Generic; 3 using System.Linq; 4 using System.Text; 5 using System.Threading.Tasks; 6  7 using System.Text.RegularExpressions; 8  9 namespace EntityCodeRuleDemo10 {11     public sealed class CodeRuleGenerator : ICodeRuleGenerator12     {13         private readonly IEnumerable
     
       _providers = new List
      
       ();14 15         internal CodeRuleGenerator(IEnumerable
       
         providers)16         {17             _providers = providers;18         }19 20         public string Generate(object entity)21         {22             var sb = new StringBuilder();23 24             foreach (var provider in _providers)25             {26                 sb.Append(provider.Generate(entity));27             }28 29             return sb.ToString();30         }31     }32 }
       
      
     

CodeRuleInterpreter.cs

1 using System; 2 using System.Collections.Generic; 3 using System.Linq; 4 using System.Text; 5 using System.Threading.Tasks; 6  7 using System.Text.RegularExpressions; 8  9 using EntityCodeRuleDemo.RuleProviders;10 11 namespace EntityCodeRuleDemo12 {13     public static class CodeRuleInterpreter14     {15         private static Dictionary
     
      > _providerFactorys = new Dictionary
      
       >();16 17         static CodeRuleInterpreter()18         {19             SetProviderFactory(new Regex("^[^<].*?[^>]?$"), LiteralRuleProvider.LiteralRuleProviderFactory);20             SetProviderFactory(new Regex("^
       <日期(:(?>
        <格式>
         .*?))?>$"), DateRuleProvider.DateRuleProviderFactory);21             SetProviderFactory(new Regex("^
         <属性(:(?>
          <名称>
           .*?))?>$"), PropertyRuleProvider.PropertyRuleProviderFactory);22 }23 24 public static void SetProviderFactory(Regex regex, Func
           
             providerFactory)25 {26 _providerFactorys[regex] = providerFactory;27 }28 29 30 public static ICodeRuleGenerator Interpret(string codeRule)31 {32 var providers = GetProviders(codeRule);33 34 return new CodeRuleGenerator(providers);35 }36 37 private static IEnumerable
            
              GetProviders(string codeRule)38 {39 var literals = codeRule.Replace("<", "$<").Replace(">", ">$").Split('$');40 41 return literals42 .Where(x => !string.IsNullOrEmpty(x))43 .Select(GetProvider)44 .ToList();45 }46 47 private static ICodeRuleProvider GetProvider(string literal)48 {49 var providerFactory = _providerFactorys50 .FirstOrDefault(x => x.Key.IsMatch(literal))51 .Value;52 53 if (providerFactory == null)54 {55 throw new FormatException("格式化错误");56 }57 58 return providerFactory(literal);59 }60 }61 }
            
           
          
         
        
       
      
     

Program.cs

1 using System; 2 using System.Collections.Generic; 3 using System.Linq; 4 using System.Text; 5 using System.Threading.Tasks; 6  7 namespace EntityCodeRuleDemo 8 { 9     class Program10     {11         static void Main(string[] args)12         {13             var employeeCode = CodeRuleInterpreter14                 .Interpret("前缀_
     <日期:yyyy_mm_dd>
      _
      <属性:namepinyin>
       ")15                 .Generate(new Employee { NamePinYin = "DUANGW" });16 17             Console.WriteLine(employeeCode);18         }19     }20 21     class Employee22     {23         public string NamePinYin { get; set; }24         public string EmployeeCode { get; set; }25     }26 }
      
     

运行效果

备注

按照这种思路，基本上能满足企业应用的多数编码规则要求。在真实的项目中，这些规则是要持久化到数据库的，这样就可以做到运行时动态的修改规则了。