Mcad学习笔记之通过反射调用類的方法,屬性,字段,索引器(2種方法)

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Type是System.Reflection功能的根 (Root)，也是存取Metadata的主要方法.
使用Type的成員可以取得相關資訊,例如建構函式(Constructor),方法,字段,屬性和類別的事件,以及模組和部署類別的組件(Assembly).

3種取得Type的方法:
1.靜態方法
Type.GetType()
2.運算符
typeof()
3.實例的方法GetType
Employee e=new Employee();
e.GetType()

在一般情況下我們调用的方法並传递给它们的参数,某些情况下可能希望根据用户操作动态调用方法.
通过Reflection命名空间
方法1是使用Type对象上的InvokeMember方法
方法2是使用MethodInfo对象上的Invoke方法

example:
先定義類Employee
其中有靜態屬性Data
實例屬性Name,ID
2個索引器

     ///   <summary>
     ///  自定義類
     ///   </summary>
     public   class  Employee
    {
         string  name;
         int  id;

        ArrayList list; 

         static   int  data;
        
         // instance .ctor()
         public  Employee(  int  id, String name ) 
        {
             this .name  =  name;
             this .id  =  id;

            list = new  ArrayList();

             this .list.Add(  " 001 "  );
             this .list.Add(  " 002 "  );
        }

         // static .ctor()
         static  Employee()
        {
            data = 119 ;
        }

         public   override   string  ToString ()
        {
             return   " Id= " +  id.ToString()  +   " , Name= "   +  name;
        }

         // instance Method "add"
         public   string  add(  string  key1, string  key2 )
        {
             string  result = key1 + key2;
             return  result;
        }
        
         // static Method "add"
         public   static   string  add(  string  key1, string  key2, string  key3 )
        {
             return  key1 + key2 + key3;
        }

         public   string  Name 
        {
             get  
            { 
                 return   name; 
            }
             set  
            { 
                name  =  value; 
            }
        }

         public   int  ID 
        {
             get  
            { 
                 return   id; 
            }
             set  
            { 
                id  =  value; 
            }
        }

         public   static   int  Data
        {
             get
            {
                 return  data;
            }
             set
            {
                data = value;
            }
        }

         ///   <summary>
         ///  by index
         ///   </summary>
         public   string   this  [  int  index ]
        {
             get
            {
                 return  list[index].ToString();
            }
             set
            {
                list[index] = value;
            }
        }

         ///   <summary>
         ///  by value
         ///   </summary>
         public   string   this  [  string  values]
        {
             set
            {
                 this [list.IndexOf(values)] = value;
            }
        }

    }

動態調用:

定義變量

             string  result = String.Empty;
             int  i;

            Type t = typeof ( Employee );
            
            Employee e = new  Employee( 1000 , " no 1000 " );

方法1是使用Type对象上的InvokeMember方法:
先動態調用類Employee的實例方法ToString
InvokeMember方法的第一個參數是要調用的方法名稱
第2個參數是位枚舉,代表搜尋的方式
第四個參數是要調用的對象,要是靜態的就用null
第五個參數是要傳送給ToString的數值,由於ToString方法是無參方法,這裡我們送一個空數組new object[]{}

1               // call instance Method "ToString"
2              result = ( typeof (Employee).InvokeMember( " ToString " ,
3                                                      BindingFlags.InvokeMethod,    
4                                                       null ,
5                                                      e,    
6                                                       new   object []{})).ToString();
7              Console.WriteLine( " instance Method 'ToString' result={0} " , result );
8 

再動態調用類Employee的實例方法add,靜態方法add
注意InvokeMember方法的第5個參數代表的是要傳送給add方法的數值
第8個參數代表的是add方法的參數名稱

             // call instance Method "add"
            result = typeof (Employee).InvokeMember( " add " ,
                                                BindingFlags.InvokeMethod,
                                                 null ,
                                                e,
                                                 new   object []{ " o1 " , " o2 " },
                                                 null ,
                                                 null ,
                                                 new   string []{ " key1 " , " key2 " }).ToString();
            Console.WriteLine( " instance Method 'add' result={0} " , result );

             // call static Method "add"
            result = typeof (Employee).InvokeMember( " add " ,
                                                BindingFlags.InvokeMethod  |  BindingFlags.Static  |  BindingFlags.Public ,
                                                 null ,
                                                 null ,
                                                 new   object []{ " o1 " , " o2 " , " o3 " },
                                                 null ,
                                                 null ,
                                                 new   string []{ " key1 " , " key2 " , " key3 " }).ToString();
            Console.WriteLine( " static Method 'add' result={0} " ,result );
            Console.WriteLine();

再修改靜態屬性Data,把它從119修改為911

 1               // call static Property
 2              i = ( int ) typeof (Employee).InvokeMember( " Data " ,
 3                                                  BindingFlags.GetProperty  |  BindingFlags.Public  |  BindingFlags.Static,
 4                                                   null ,
 5                                                   null ,
 6                                                   new   object []{});
 7              Console.WriteLine( " static Property 'Data'={0} " , i );
 8 
 9               // update static Property
10               typeof (Employee).InvokeMember( " data " ,
11                                              BindingFlags.SetField  |  BindingFlags.NonPublic  |  BindingFlags.Static,
12                                               null ,
13                                               null ,
14                                               new   object []{ 911 });
15              Console.WriteLine( " update static Property  " );
16 
17               // call static Property
18              i = ( int ) typeof (Employee).InvokeMember( " Data " ,
19                                                  BindingFlags.GetProperty  |  BindingFlags.Public  |  BindingFlags.Static,
20                                                   null ,
21                                                   null ,
22                                                   new   object []{});
23              Console.WriteLine(  " again call static Property 'Data'={0} " ,i );
24              Console.WriteLine();
25 

再修改實例屬性Name,把它從no 1000修改為w

 1               // read instance Property
 2              result = typeof (Employee).InvokeMember( " Name " ,
 3                                                  BindingFlags.GetProperty ,
 4                                                   null ,    
 5                                                  e,    
 6                                                   new   object []{}).ToString();
 7              Console.WriteLine(  " instance Property 'Name'={0} " , result );
 8 
 9               // update instance property
10               typeof (Employee).InvokeMember( " name " , 
11                                              BindingFlags.SetField  |  BindingFlags.NonPublic   |  BindingFlags.Instance    ,
12                                               null ,
13                                              e,
14                                               new   object []{ " w " });
15              Console.WriteLine( " update instance property  " );
16              
17               // again call read instance Property
18              result = typeof (Employee).InvokeMember( " Name " ,
19                                                      BindingFlags.GetProperty ,
20                                                       null ,    
21                                                      e,
22                                                       new   object []{}).ToString();
23              Console.WriteLine(  " again call instance Property 'Name'={0} " , result );
24              Console.WriteLine();
25 

再修改索引器,把索引器的第2個(index[1])內容修改為222
注意修改索引器的InvokeMember方法,第5個參數的數組new object[]{"002","222"}
将要设置元素的索引值放在对象数组的第一个元素中,将要设置的值作为第二个元素

 1               // call index[1] 
 2              result = typeof (Employee).InvokeMember( " Item " ,
 3                                                      BindingFlags.GetProperty,
 4                                                       null ,
 5                                                      e,
 6                                                       new   object []{ 1 }).ToString() ;
 7              Console.WriteLine( " index[1]={0} " , result);
 8 
 9               // update  index[1] 
10               typeof (Employee).InvokeMember( " Item " ,
11                                              BindingFlags.SetProperty,
12                                               null ,    
13                                              e,
14                                               new   object []{ " 002 " , " 222 " });
15              Console.WriteLine( " update  index[1]  " );
16 
17               // again call index[1]
18              result = typeof (Employee).InvokeMember( " Item " ,
19                                                  BindingFlags.GetProperty,
20                                                   null ,
21                                                  e,
22                                                   new   object []{ 1 }).ToString() ;
23 
24              Console.WriteLine( " again call index[1]={0} " , result);
25              Console.WriteLine();
26 

調用構造器
InvokeMember方法的第1個參數為空字符""

1               // call instance .ctor()
2              Employee employee = (Employee) typeof (Employee).InvokeMember( "" ,
3                                                                          BindingFlags.CreateInstance,
4                                                                           null ,
5                                                                           null ,
6                                                                           new   object []{ 123 , " no 123 " });
7              
8              Console.WriteLine(employee.ToString());
9              Console.WriteLine();

方法2是使用MethodInfo对象上的Invoke方法:

 1               // call Instance Method 'add'
 2              MethodInfo methodInfo1 = t.GetMethod( " add " ,BindingFlags.Instance  |  BindingFlags.Public);
 3               // Instance Method,first parameter is one Instance 
 4              result = methodInfo1.Invoke( new  Employee( 1 , "" ) , new   object []{ " key1 " , " key2 " }).ToString();
 5              Console.WriteLine( " call Instance Method 'add' result={0} " ,result);
 6 
 7               // call Static Method 'add'
 8              MethodInfo methodInfo2 = t.GetMethod( " add " ,BindingFlags.Static  |  BindingFlags.Public);
 9               // Static Method,first parameter is Null 
10              result = methodInfo2.Invoke( null ,     new   object []{ " key1 " , " key2 " , " key3 " }).ToString();
11              Console.WriteLine( " call Static Method 'add' result={0} " ,result);
12 

結果圖片:

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