C#反射字符串转为实体类，并做为参数传入泛型方法中使用

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原作者: [db:作者] 来自: [db:来源] 收藏邀请

工作中有这样一个需求，有N张不同的报表，每张报表对应一个数据源，统计数据采用内存方式，首先在内在里定义了数据源对应实体。统计条件用lamdba表达式式实现，通过工具对单元格进行定义。在实现过程中针对每一张表来写取数显示是很Low的了，取数条件定义都是规则的，统计实现就是一段C#代码，但是要针对不同的数据源也就是不同的List<Entity>，通过研究发现通过泛型和反射可以实现。

根据字符串获取实体类型

 1 private Type getEntity(string typeName)
 2 {
 3     var workPath = AppDomain.CurrentDomain.BaseDirectory;
 4     string[] files = Directory.GetFiles(workPath, "XXX.Utils.dll", SearchOption.TopDirectoryOnly);
 5     foreach (string file in files)
 6     {
 7         string ext = file.Substring(file.LastIndexOf("."));
 8         if (ext != ".dll") continue;
 9         try
10         {
11             Assembly asm = Assembly.LoadFile(file);
12             Type[] allTypes = asm.GetTypes();
13             foreach (Type t in allTypes)
14             {
15                 if (t.IsSubclassOf(typeof(XXDataRecord)))
16                 {
17                     if (t.Name.ToUpper().IsSame(typeName.ToUpper()))
18                         return t;
19                 }
20             }
21         }
22         catch
23         {
24             return null;
25         }
26     }
27     return null;
28 }

泛型方法定义

1 public XXDataMemory BuildDataMemoryPattern<T>(XXParams zb, string id) where T : XXDataRecord, new()

调用方法代码

 1 var obj = new GenerateDataHelper(_Param);
 2 Type myGenericClassType = obj.GetType();
 3 //MakeGenericMethod 设置泛型参数类型
 4 MethodInfo mi = myGenericClassType.GetMethod("BuildDataMemoryPattern").MakeGenericMethod(typeEntity);
 5 int count = 0;
 6 //设置调用方法参数
 7 object[] invokeArgs = new object[] { zb, id, count };
 8 //调用
 9 var dt = (DataTable)mi.Invoke(obj, invokeArgs);
10 //获取回返数据
11 recordCount = (int)invokeArgs[9];

下面是全部代码，具体功能实现略过

 1 public class UtilFetchHelper 
 2 {
 3     //获取实体类型
 4     private Type getEntity(string typeName)
 5     {
 6         var workPath = AppDomain.CurrentDomain.BaseDirectory;
 7         string[] files = Directory.GetFiles(workPath, "XXX.Utils.dll", SearchOption.TopDirectoryOnly);
 8         foreach (string file in files)
 9         {
10             string ext = file.Substring(file.LastIndexOf("."));
11             if (ext != ".dll") continue;
12             try
13             {
14                 Assembly asm = Assembly.LoadFile(file);
15                 Type[] allTypes = asm.GetTypes();
16                 foreach (Type t in allTypes)
17                 {
18                     if (t.IsSubclassOf(typeof(XXDataRecord)))
19                     {
20                         if (t.Name.ToUpper().IsSame(typeName.ToUpper()))
21                             return t;
22                     }
23                 }
24             }
25             catch
26             {
27                 return null;
28             }
29         }
30         return null;
31     }
32 
33     public DataTable BuildDataMemoryPattern(XXParams zb, string id, out int recordCount)
34     {
35         //根据传入参数获取实体名称
36         var entityName = GetDataSourceEntityName(zb);
37         //获取实体类型
38         Type typeEntity = getEntity(entityName);
39         if (typeEntity == null)
40             return  null;
41         var obj = new GenerateDataHelper(_Param);
42         Type myGenericClassType = obj.GetType();
43         MethodInfo mi = myGenericClassType.GetMethod("BuildDataMemoryPattern").MakeGenericMethod(typeEntity);
44         int count = 0;
45         object[] invokeArgs = new object[] { zb, id, count };
46         var dt = (DataTable)mi.Invoke(obj, invokeArgs);
47         //这里获取回返数据
48         recordCount = (int)invokeArgs[9];
49         return dt;
50     }
51 }
52 
53 public class GenerateDataHelper
54 {
55     private List<XXDataRecord> _DataList;
56     private List<XXDataRecord> DataList
57     {
58         set { _DataList = value; }
59         get { return _DataList; }
60     }    
61     
62     private List<T> GetDataSource<T>() where T : XXDataRecord, new()
63     {
64         var _DataList = new List<T>();
65         var dt = DB.ExecuteDataTable("Select * From XX");
66         for (int i = 0; i < dt.Rows.Count; i++)
67         {
68             var dataEnt = new T();
69             for (int j = 0; j < dt.Columns.Count; j++)
70             {
71                 dataEnt[dt.Columns[j].ColumnName] = dt.Rows[i][j];
72             }
73             _DataList.Add(dataEnt);
74         }
75         return _DataList;        
76      }
77         
78         
79     public XXDataMemory BuildDataMemoryPattern<T>(XXParams zb, string id) where T : XXDataRecord, new()
80     {
81         List<T> DataList = new List<T>();
82         DataList = GetDataSource<T>();
83         //以下是具体实现代码 针对DataList查询操作
84     }
85 }