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
/// 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
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[]{}
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
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
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
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
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""
2 Employee employee = (Employee) typeof (Employee).InvokeMember( "" ,
3 BindingFlags.CreateInstance,
4 null ,
5 null ,
6
