C#動態調用泛型類、泛型方法

時間  2019-11-12
標籤 c# 動態 調用 方法 欄目 C# 简体版
原文   原文鏈接

在製做一個批量序列化工具時遇到了以下問題，在此記錄一下，僅供參考。工具

      主程序加載另外一個程序集，將其中的全部類取出，而後對這些類分別調用泛型類或泛型方法。控制檯程序解決方案以下：測試

  • Main工程：提供Worker類進行數據操做，XMLTool<T>泛型類將數據集序列化爲.xml文檔，RootCollection<T>類封裝數據集
    • Worker類

    　　     提供成員方法void DoWork<T>()、List<T> GetList<T>()、靜態成員方法StaticDoWork<T>()，代碼以下：this

    複製代碼 
     1 public class Worker
     2     {
     3         public Worker()
     4         {
     5         }
     6 
     7         public void DoWork<T>()
     8         {
     9             Type t = typeof(T);
    10             Console.WriteLine("Get Class: {0}", t.Name);
    11             PropertyInfo[] properties = t.GetProperties();
    12             foreach (PropertyInfo property in properties)
    13             {
    14                 Console.WriteLine("\tproperty.Name: " + property.Name + "\tproperty.MemberType: " + property.PropertyType);
    15             }
    16         }
    17 
    18         public static void StaticDoWork<T>()
    19         {
    20             Type t = typeof(T);
    21             Console.WriteLine("Get Class: {0}", t.Name);
    22             PropertyInfo[] properties = t.GetProperties();
    23             foreach (PropertyInfo property in properties)
    24             {
    25                 Console.WriteLine("\tproperty.Name: " + property.Name + "\tproperty.MemberType: " + property.PropertyType);
    26             }
    27         }
    28 
    29         public List<T> GetList<T>()
    30         {
    31             Console.WriteLine("Generate List for [{0}]", typeof(T).Name);
    32             return new List<T>() 
    33             { 
    34                 Activator.CreateInstance<T>(), 
    35                 Activator.CreateInstance<T>() 
    36             };
    37         }
    38     }
    複製代碼

     

    • XMLTool<T>類
      複製代碼 
       1publicclass XMLTool<T>
       2     {
       3publicstaticvoid XmlSerialize_Save(List<T> needSerializedList, string xmlDirPath, string xmlFileName)
       4         {
       5             RootCollection<T> collection = new RootCollection<T>();
       6             collection.ItemList = needSerializedList;
       7if (!Directory.Exists(xmlDirPath))
       8                 Directory.CreateDirectory(xmlDirPath);
       9using (System.IO.FileStream stream = new System.IO.FileStream(xmlFileName, System.IO.FileMode.Create))
      10             {
      11                 System.Xml.Serialization.XmlSerializer serializer = new System.Xml.Serialization.XmlSerializer(collection.GetType());
      12                 serializer.Serialize(stream, collection);
      13             }
      14         }
      15     }
      複製代碼
    • RootCollection<T>類：
      複製代碼 
       1     [Serializable]
       2     public class RootCollection<T>
       3     {
       4         public RootCollection()
       5         {
       6             itemList = new List<T>();
       7         }
       8 
       9         private List<T> itemList;
      10 
      11         public List<T> ItemList
      12         {
      13             get { return itemList; }
      14             set { itemList = value; }
      15         }
      16     }
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  • MockClassLib工程：提供BaseEntity、Apple、Cat和Person類
    • BaseEntity類：抽象類，負責初始化類成員
      複製代碼 
       1     public abstract class BaseEntity
       2     {
       3         public BaseEntity()
       4         {
       5             InitiaWithNull();
       6         }
       7
       8         private void InitiaWithNull()
       9         {
      10             Type type = this.GetType();
      11             PropertyInfo[] properties = type.GetProperties();
      12             string[] PropNames = new string[properties.Length];
      13             Dictionary<string, PropertyInfo> PropNameToInfo = new Dictionary<string, PropertyInfo>();
      14             for (int i = 0; i < properties.Length; i++)
      15             {
      16                 PropNames[i] = properties[i].Name;
      17                 PropNameToInfo.Add(PropNames[i], properties[i]);
      18             }
      19
      20             foreach (string propname in PropNames)
      21             {
      22                 string proptype = PropNameToInfo[propname].PropertyType.Name;
      23
      24                 object value = null;
      25                 if (NullValue.Keys.Contains(proptype))
      26                     value = NullValue[proptype];
      27
      28                 type.GetProperty(propname).SetValue(this, value, null);
      29             }
      30         }
      31
      32         private static readonly Dictionary<string, object> NullValue = new Dictionary<string, object>() 
      33             { 
      34                 { "String", String.Empty }, 
      35                 { "DateTime", DateTime.MinValue},
      36                 { "Decimal", Decimal.MinValue}
      37             };
      38     }
      複製代碼
    • Apple、Cat和Person類：測試類，繼承於BaseEntity
      複製代碼 
       1     public class Apple : BaseEntity
       2     {
       3        public string Color { get; set; }
       4     }
       5
       6     public class Cat : BaseEntity
       7     {
       8        public string Type { get; set; }
       9     }
      10
      11     public class Person : BaseEntity
      12     {
      13        public int ID { get; set; }
      14        public string Name { get; set; }
      15     }
      複製代碼

 

      Main工程的Program的Main方法中，通常狀況下，調用Worker的泛型方法來處理測試類的話，能夠寫爲：spa

      Worker worker = new Worker();code

      worker.DoWork<Apple>();xml

      worker.DoWork<Cat>();對象

      worker.DoWork<Person>();blog

      可是，若是MockClassLib中須要處理的類型很是多時，這樣顯示調用必然是不靈活的，應當怎樣向泛型方法DoWork<T>()的尖括號中動態傳入類型呢？繼承

      考慮代碼：ci

複製代碼 
            //Load assembly
            Assembly mockAssembly = Assembly.LoadFrom("MockClassLibrary.dll");
            Type[] typeArray = mockAssembly.GetTypes();

            //Create instance of Worker          
            Worker worker = new Worker();
            foreach(Type curType in typeArray)
            {
                  worker.DoWork<curType>();   //Error
            }
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      能夠看到，Type類型的實例是沒法直接傳入泛型方法的尖括號中的，T要求顯式指明類型名。

      下面經過反射方式來獲取泛型方法，並建立特定類型的泛型方法。

  • 對於非靜態方法：public void DoWork<T>()

          對於非靜態方法，調用MethodInfo.Invoke(object, object[])時，第一個參數須要指明泛型方法的全部者（即這裏建立的worker對象），第二個參數爲泛

          型方法的參數列表，DoWork<T>()沒有輸入參數，因此設爲null

複製代碼 
//Create an instance of Worker
Worker worker = new Worker();       

//Get type of Worker
Type workerType = typeof(Worker);

 //Get Generic Method
MethodInfo doWorkMethod = workerType.GetMethod("DoWork");

//Invoke DoWork<T> with different Type
foreach (Type curType in typeArray)
{
    if (curType.IsClass && !curType.IsAbstract)//Filter BaseEntity
    {
        MethodInfo curMethod = doWorkMethod.MakeGenericMethod(curType);
        curMethod.Invoke(worker, null);//Member method，use instance
    }
}
複製代碼
  • 對於靜態方法：public static void StaticDoWork<T>()

          不一樣於非靜態方法，這裏直接反射的類靜態方法，因此Invoke()的第一個參數設爲null

複製代碼 
//Get type of Worker
Worker worker = new Worker();

//Get Generic Method
MethodInfo staticDoWorkMethod = workerType.GetMethod("StaticDoWork");

//Invoke StaticDoWork<T>
foreach (Type curType in typeArray)
{
    if (curType.IsClass && !curType.IsAbstract)
    {
        MethodInfo curMethod = staticDoWorkMethod.MakeGenericMethod(curType);
        curMethod.Invoke(null, null);//Static method
    }
}
複製代碼
  • 對於有返回值的非靜態方法：public List<T> GetList()

          如同動態調用DoWork<T>()方法同樣，只是在處理返回值時，可使用下面的方法

1 IList tempList = (IList)curMethod.Invoke(worker, null);
2 //Or
3 IEnumerable tempList = (IEnumerable)curMethod.Invoke(worker, null);
  • 對於泛型類：XMLTool<T>

          下面要使用泛型類XMLTool<T>的靜態方法public static void XmlSerialize_Save(List<T> list, string dirPath, string fileName)方法。

          首先應經過反射構造出指定類型的泛型類XMLTool<T>，再反射出其中的XmlSerialize_Save方法並使用。

複製代碼 
 1 //Use Generic Class
 2 Type xmlToolType = typeof(XMLTool<>).MakeGenericType(curType);
 3 
 4 //Get method
 5 MethodInfo saveMethod = xmlToolType.GetMethod("XmlSerialize_Save");
 6 
 7 //Invoke
 8 saveMethod.Invoke
 9 (
10     null, //Static method
11     new object[] { resultList, @"c:\", @"c:\Test_" + curType.Name + ".xml" }

12 );
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       Program-->Main()方法的所有代碼：

複製代碼 
 1 namespace RetrieveUnknownClass
 2 {
 3     class Program
 4     {
 5         static void Main(string[] args)
 6         {
 7             //Load assembly
 8             Assembly mockAssembly = Assembly.LoadFrom("MockClassLibrary.dll");
 9             Type[] typeArray = mockAssembly.GetTypes();
10 
11             //Create instance of Worker          
12             Type workerType = typeof(Worker);
13             Worker worker = new Worker();
14 
15             #region Member method
16 
17             Console.WriteLine(">>>>>>>>>Use Generic Method：");
18             MethodInfo doWorkMethod = workerType.GetMethod("DoWork");
19 
20             //Invoke DoWork<T>
21             foreach (Type curType in typeArray)
22             {
23                 if (curType.IsClass && !curType.IsAbstract)
24                 {
25                     MethodInfo curMethod = doWorkMethod.MakeGenericMethod(curType);
26                     curMethod.Invoke(worker, null);//Member method，use instance
27                 }
28             }
29 
30             #endregion
31 
32             #region Static method
33 
34             Console.WriteLine("\r\n>>>>>>>>>Use Static Generic Method：");
35             MethodInfo staticDoWorkMethod = workerType.GetMethod("StaticDoWork");
36 
37             //Invoke StaticDoWork<T>
38             foreach (Type curType in typeArray)
39             {
40                 if (curType.IsClass && !curType.IsAbstract)
41                 {
42                     MethodInfo curMethod = staticDoWorkMethod.MakeGenericMethod(curType);
43                     curMethod.Invoke(null, null);//Static method
44                 }
45             }
46 
47             #endregion
48 
49             #region Get A List & Serialize It to Xml File With Generic 
50 
51             Console.WriteLine("\r\n>>>>>>>>>Get List By Generic Method：");
52             MethodInfo getListMethod = workerType.GetMethod("GetList");
53 
54             foreach (Type curType in typeArray)
55             {
56                 if (curType.IsClass && !curType.IsAbstract)
57                 {
58                     MethodInfo curMethod = getListMethod.MakeGenericMethod(curType);
59                     //Generate List
60                     IList resultList = (IList)curMethod.Invoke(worker, null);
61                     //Show List
62                     ShowList(resultList);
63                     //Use Generic Class
64                     Type xmlToolType = typeof(XMLTool<>).MakeGenericType(curType);
65                     MethodInfo saveMethod = xmlToolType.GetMethod("XmlSerialize_Save");
66 
67                     saveMethod.Invoke
68                         (
69                             null, //Static method
70                             new object[] { resultList, @"c:\", @"c:\Test_" + curType.Name + ".xml" }
71                         );
72                 }
73             }
74             
75             Console.WriteLine("Serialization Completed...\r\n");
76             #endregion
77         }
78 
79         public static void ShowList(IList list)
80         {
81             Console.WriteLine("Type of list: {0}\r\nCount of current list: {1}\r\nType of item in list: {2}\r\n", 
82                 list.GetType(), 
83                 list.Count, 
84                 list[0].GetType());
85         }
86     }
87 }
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