Článek
11/18/2011

FieldInfo Class

Microsoft Silverlight will reach end of support after October 2021. Learn more.

Discovers the attributes of a field and provides access to field metadata.

Inheritance Hierarchy

System.Object
  System.Reflection.MemberInfo
    System.Reflection.FieldInfo
      System.Reflection.Emit.FieldBuilder

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

Syntax

'Declaration
<ComVisibleAttribute(True)> _
<ClassInterfaceAttribute(ClassInterfaceType.None)> _
Public MustInherit Class FieldInfo _
    Inherits MemberInfo

[ComVisibleAttribute(true)]
[ClassInterfaceAttribute(ClassInterfaceType.None)]
public abstract class FieldInfo : MemberInfo

The FieldInfo type exposes the following members.

Constructors

	Name	Description
	FieldInfo	Initializes a new instance of the FieldInfo class.

Top

Properties

	Name	Description
	Attributes	Gets the attributes that are associated with this field.
	DeclaringType	Gets the class that declares this member. (Inherited from MemberInfo.)
	FieldHandle	Gets a handle to the internal metadata representation of a field.
	FieldType	Gets the type of this field object.
	IsAssembly	Gets a value that indicates whether the potential visibility of this field is described by FieldAttributes.Assembly; that is, the field is visible at most to other types in the same assembly, and is not visible to derived types outside the assembly.
	IsFamily	Gets a value that indicates whether the visibility of this field is described by FieldAttributes.Family; that is, the field is visible only within its class and derived classes.
	IsFamilyAndAssembly	Gets a value that indicates whether the visibility of this field is described by FieldAttributes.FamANDAssem; that is, the field can be accessed from derived classes, but only if they are in the same assembly.
	IsFamilyOrAssembly	Gets a value that indicates whether the potential visibility of this field is described by FieldAttributes.FamORAssem; that is, the field can be accessed by derived classes wherever they are, and by classes in the same assembly.
	IsInitOnly	Gets a value that indicates whether the field can be set only in the body of the constructor.
	IsLiteral	Gets a value that indicates whether the value is written at compile time and cannot be changed.
	IsNotSerialized	Gets a value that indicates whether this field has the NotSerialized attribute.
	IsPinvokeImpl	Gets a value that indicates whether the corresponding PinvokeImpl attribute is set in FieldAttributes.
	IsPrivate	Gets a value that indicates whether the field is private.
	IsPublic	Gets a value that indicates whether the field is public.
	IsSpecialName	Gets a value that indicates whether the field has a name that has special significance.
	IsStatic	Gets a value that indicates whether the field is static (Shared in Visual Basic).
	MemberType	Gets a value that indicates that this member is a field. (Overrides MemberInfo.MemberType.)
	MetadataToken	Gets a value that identifies a metadata element. (Inherited from MemberInfo.)
	Module	Gets the module in which the type that declares the member represented by the current MemberInfo is defined. (Inherited from MemberInfo.)
	Name	Gets the name of the current member. (Inherited from MemberInfo.)
	ReflectedType	Gets the class object that was used to obtain this instance of MemberInfo. (Inherited from MemberInfo.)

Top

Methods

	Name	Description
	Equals(Object)	Determines whether the specified Object is equal to the current Object. (Inherited from Object.)
	Finalize	Allows an object to try to free resources and perform other cleanup operations before the Object is reclaimed by garbage collection. (Inherited from Object.)
	GetCustomAttributes(Boolean)	When overridden in a derived class, returns an array of all custom attributes applied to this member. (Inherited from MemberInfo.)
	GetCustomAttributes(Type, Boolean)	When overridden in a derived class, returns an array of custom attributes applied to this member and identified by Type. (Inherited from MemberInfo.)
	GetFieldFromHandle(RuntimeFieldHandle)	Gets a FieldInfo for the field represented by the specified handle.
	GetFieldFromHandle(RuntimeFieldHandle, RuntimeTypeHandle)	Gets a FieldInfo for the field represented by the specified handle, for the specified generic type.
	GetHashCode	Serves as a hash function for a particular type. (Inherited from Object.)
	GetRawConstantValue	Returns a literal value associated with the field by a compiler.
	GetType	Gets the Type of the current instance. (Inherited from Object.)
	GetValue	When overridden in a derived class, returns the value of a field supported by a given object.
	IsDefined	When overridden in a derived class, indicates whether one or more attributes of the specified type or of its derived types is applied to this member. (Inherited from MemberInfo.)
	MemberwiseClone	Creates a shallow copy of the current Object. (Inherited from Object.)
	SetValue(Object, Object)	Sets the value of the field that is supported by the given object.
	SetValue(Object, Object, BindingFlags, Binder, CultureInfo)	When overridden in a derived class, sets the value of the field with the specified constraints on type conversion.
	ToString	Returns a string that represents the current object. (Inherited from Object.)

Top

Remarks

The FieldInfo class does not have a public constructor. FieldInfo objects are obtained by calling either Type.GetFields or Type.GetField.

Fields are variables that are defined in the class. FieldInfo provides access to the metadata for a field in a class and also enables late-bound access to the value of a field. In Silverlight, you can get the metadata of any field, regardless of its access level, but you cannot use FieldInfo to bypass access-level protection when you get or set the value of a field.

Examples

The following example uses the Type.GetFields method to get the fields of the Example class, and then displays information about the fields.

Note:
To run this example, see Building Examples That Use a Demo Method and a TextBlock Control.

Imports System.Reflection

Public Class Example
   Public myField1 As Integer = 0
   Protected myField2 As String = Nothing

   Public Shared Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock)
      Dim myFieldInfo() As FieldInfo
      Dim myType As Type = GetType(Example)
      ' Get the type and fields of Example.
      myFieldInfo = myType.GetFields(BindingFlags.NonPublic Or _
                    BindingFlags.Instance Or BindingFlags.Public)
      outputBlock.Text &= ControlChars.NewLine & "The fields of " & _
                    "Example class are " & ControlChars.NewLine & vbCrLf
      ' Display the field information of Example.
      Dim i As Integer
      For i = 0 To myFieldInfo.Length - 1
         outputBlock.Text &= String.Format(ControlChars.NewLine + "Name            : {0}", myFieldInfo(i).Name) & vbCrLf
         outputBlock.Text &= String.Format("Declaring Type  : {0}", myFieldInfo(i).DeclaringType) & vbCrLf
         outputBlock.Text &= String.Format("IsPublic        : {0}", myFieldInfo(i).IsPublic) & vbCrLf
         outputBlock.Text &= String.Format("MemberType      : {0}", myFieldInfo(i).MemberType) & vbCrLf
         outputBlock.Text &= String.Format("FieldType       : {0}", myFieldInfo(i).FieldType) & vbCrLf
         outputBlock.Text &= String.Format("IsFamily        : {0}", myFieldInfo(i).IsFamily) & vbCrLf
      Next i
   End Sub
End Class

using System;
using System.Reflection;

public class Example
{
   public int myField1 = 0;
   protected string myField2 = null;
   public static void Demo(System.Windows.Controls.TextBlock outputBlock)
   {
      FieldInfo[] myFieldInfo;
      Type myType = typeof(Example);
      // Get the type and fields of Example.
      myFieldInfo = myType.GetFields(BindingFlags.NonPublic | BindingFlags.Instance
          | BindingFlags.Public);
      outputBlock.Text += "\nThe fields of " +
          "Example are \n" + "\n";
      // Display the field information of Example.
      for (int i = 0; i < myFieldInfo.Length; i++)
      {
         outputBlock.Text += String.Format("\nName            : {0}", myFieldInfo[i].Name) + "\n";
         outputBlock.Text += String.Format("Declaring Type  : {0}", myFieldInfo[i].DeclaringType) + "\n";
         outputBlock.Text += String.Format("IsPublic        : {0}", myFieldInfo[i].IsPublic) + "\n";
         outputBlock.Text += String.Format("MemberType      : {0}", myFieldInfo[i].MemberType) + "\n";
         outputBlock.Text += String.Format("FieldType       : {0}", myFieldInfo[i].FieldType) + "\n";
         outputBlock.Text += String.Format("IsFamily        : {0}", myFieldInfo[i].IsFamily) + "\n";
      }
   }
}

Version Information

Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Xbox 360, Windows Phone OS 7.0

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

Thread Safety

This type is thread safe.

Sdílet prostřednictvím