C#動態調用泛型類、泛型方法

在製作一個批量序列化工具時遇到瞭如下問題，在此記錄一下，僅供參考。主程式載入另一個程式集，將其中的所有類取出，然後對這些類分別調用泛型類或泛型方法。控制台程式解決方案如下： Main工程：提供Worker類進行數據操作，XMLTool<T>泛型類將數據集序列化為.xml文檔，RootCollect ...

在製作一個批量序列化工具時遇到瞭如下問題，在此記錄一下，僅供參考。

主程式載入另一個程式集，將其中的所有類取出，然後對這些類分別調用泛型類或泛型方法。控制台程式解決方案如下：

Main工程：提供Worker類進行數據操作，XMLTool<T>泛型類將數據集序列化為.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>()，代碼如下：

 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     }

XMLTool<T>類

 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     }

RootCollection<T>類：

 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     }

MockClassLib工程：提供BaseEntity、Apple、Cat和Person類

BaseEntity類：抽象類，負責初始化類成員

 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     }

Apple、Cat和Person類：測試類，繼承於BaseEntity

 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     }

Main工程的Program的Main方法中，一般情況下，調用Worker的泛型方法來處理測試類的話，可以寫為：

Worker worker = new Worker();

worker.DoWork<Apple>();

worker.DoWork<Cat>();

worker.DoWork<Person>();

但是，如果MockClassLib中需要處理的類型非常多時，這樣顯示調用必然是不靈活的，應當怎樣向泛型方法DoWork<T>()的尖括弧中動態傳入類型呢？

考慮代碼：

            //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
            }

可以看到，Type類型的實例是無法直接傳入泛型方法的尖括弧中的，T要求顯式指明類型名。

下麵通過反射方式來獲取泛型方法，並創建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，第一個參數需要指明泛型方法的所有者（即這裡創建的worker對象），第二個參數為泛

型方法的參數列表，DoWork<T>()沒有輸入參數，所以設為null

//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
    }
}

對於靜態方法：public static void StaticDoWork<T>()

不同於非靜態方法，這裡直接反射的類靜態方法，所以Invoke()的第一個參數設為null

//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
    }
}

對於有返回值的非靜態方法：public List<T> GetList()

如同動態調用DoWork<T>()方法一樣，只是在處理返回值時，可以使用下麵的方法

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>

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

首先應通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。

 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 );

Program-->Main()方法的全部代碼：

 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 }