Type类 (Type Class)

Represents type declarations: class types, interface types, array types, value types, enumeration types, type parameters, generic type definitions, and open or closed constructed generic types.

Namespace: System
Assembly: mscorlib (in mscorlib.dll)

Visual Basic (Usage)

Dim instance As Type

Remarks

Type is the root of the System.Reflection functionality and is the primary way to access metadata. Use the members of Type to get information about a type declaration, such as the constructors, methods, fields, properties, and events of a class, as well as the module and the assembly in which the class is deployed.

The C# typeof operator (GetType operator in Visual Basic, typeid operator in Visual C++) returns a Type object.

A Type object that represents a type is unique; that is, two Type object references refer to the same object if and only if they represent the same type. This allows for comparison of Type objects using reference equality.

This class is thread safe; multiple threads can concurrently read from an instance of this type. An instance of Type can represent any of the following types:

• Classes
• Value types
• Arrays
• Interfaces
• Pointers
• Enumerations
• Constructed generic types and generic type definitions
• Type arguments and type parameters of constructed generic types, generic type definitions, and generic method definitions

Examples

The following code example shows a few representative features of Type. The C# typeof operator (GetType operator in Visual Basic, typeid operator in Visual C++) is used to get a Type object representing String. From this Type object, the GetMethod method is used to get a MethodInfo representing the Substring overload that takes a starting location and a length.

To identify the overload signature, the code example creates a temporary array containing two Type objects representing int (Integer in Visual Basic).

Imports System
Imports System.Reflection
Module Example
    Sub Main() 
        Dim t As Type = GetType(String)
        Dim substr As MethodInfo = t.GetMethod("Substring", _
            New Type() { GetType(Integer), GetType(Integer) })
        Dim result As Object = _ 
            substr.Invoke("Hello, World!", New Object() { 7, 5 })
        Console.WriteLine("{0} returned ""{1}"".", substr, result)
    End Sub 
End Module
' This code example produces the following output:
'
'System.String Substring(Int32, Int32) returned "World".

 

作者:      收录日期: 2008-12-15
来源:

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