Type.GetField Type.GetField Type.GetField Type.GetField Method

定义

获取当前 Type 的特定字段。Gets a specific field of the current Type.

重载

GetField(String) GetField(String) GetField(String) GetField(String)

搜索具有指定名称的公共字段。Searches for the public field with the specified name.

GetField(String, BindingFlags) GetField(String, BindingFlags) GetField(String, BindingFlags) GetField(String, BindingFlags)

使用指定绑定约束搜索指定字段。Searches for the specified field, using the specified binding constraints.

GetField(String) GetField(String) GetField(String) GetField(String)

搜索具有指定名称的公共字段。Searches for the public field with the specified name.

public:
 virtual System::Reflection::FieldInfo ^ GetField(System::String ^ name);
public System.Reflection.FieldInfo GetField (string name);
abstract member GetField : string -> System.Reflection.FieldInfo
override this.GetField : string -> System.Reflection.FieldInfo
Public Function GetField (name As String) As FieldInfo

参数

name
String String String String

包含要获取的数据字段的名称的字符串。The string containing the name of the data field to get.

返回

如找到,则为表示具有指定名称的公共字段的对象;否则为 nullAn object representing the public field with the specified name, if found; otherwise, null.

实现

异常

Type 对象是尚未调用其 CreateType() 方法的 TypeBuilderThis Type object is a TypeBuilder whose CreateType() method has not yet been called.

示例

下面的示例获取Type指定的类对象,获取FieldInfo对象的字段,并显示字段的值。The following example gets the Type object for the specified class, obtains the FieldInfo object for the field, and displays the value of the field.

using namespace System;
using namespace System::Reflection;
using namespace System::Security;
public ref class MyFieldClassA
{
public:
   String^ field;
   MyFieldClassA()
   {
      field = "A Field";
   }


   property String^ Field 
   {
      String^ get()
      {
         return field;
      }

      void set( String^ value )
      {
         if ( field != value )
         {
            field = value;
         }
      }

   }

};

public ref class MyFieldClassB
{
public:
   String^ field;
   MyFieldClassB()
   {
      field = "B Field";
   }


   property String^ Field 
   {
      String^ get()
      {
         return field;
      }

      void set( String^ value )
      {
         if ( field != value )
         {
            field = value;
         }
      }

   }

};

int main()
{
   try
   {
      MyFieldClassB^ myFieldObjectB = gcnew MyFieldClassB;
      MyFieldClassA^ myFieldObjectA = gcnew MyFieldClassA;
      Type^ myTypeA = Type::GetType( "MyFieldClassA" );
      FieldInfo^ myFieldInfo = myTypeA->GetField( "field" );
      Type^ myTypeB = Type::GetType( "MyFieldClassB" );
      FieldInfo^ myFieldInfo1 = myTypeB->GetField( "field", static_cast<BindingFlags>(BindingFlags::Public | BindingFlags::Instance) );
      Console::WriteLine( "The value of the field is : {0} ", myFieldInfo->GetValue( myFieldObjectA ) );
      Console::WriteLine( "The value of the field is : {0} ", myFieldInfo1->GetValue( myFieldObjectB ) );
   }
   catch ( SecurityException^ e ) 
   {
      Console::WriteLine( "Exception Raised!" );
      Console::WriteLine( "Message : {0}", e->Message );
   }
   catch ( ArgumentNullException^ e ) 
   {
      Console::WriteLine( "Exception Raised!" );
      Console::WriteLine( "Message : {0}", e->Message );
   }
   catch ( Exception^ e ) 
   {
      Console::WriteLine( "Exception Raised!" );
      Console::WriteLine( "Message : {0}", e->Message );
   }

}


using System;
using System.Reflection;

public class MyFieldClassA
{
    public string Field = "A Field";
}

public class MyFieldClassB
{
    private string field = "B Field";
    public string Field 
    {
        get
        {
            return field;
        }
        set
        {
            if (field!=value)
            {
                field=value;
            }
        }
    }
}

public class MyFieldInfoClass
{
    public static void Main()
    {
        MyFieldClassB myFieldObjectB = new MyFieldClassB();
        MyFieldClassA myFieldObjectA = new MyFieldClassA();

        Type myTypeA = typeof(MyFieldClassA);
        FieldInfo myFieldInfo = myTypeA.GetField("Field");

        Type myTypeB = typeof(MyFieldClassB);
        FieldInfo myFieldInfo1 = myTypeB.GetField("field", 
            BindingFlags.NonPublic | BindingFlags.Instance);

        Console.WriteLine("The value of the public field is: '{0}'", 
            myFieldInfo.GetValue(myFieldObjectA));
        Console.WriteLine("The value of the private field is: '{0}'", 
            myFieldInfo1.GetValue(myFieldObjectB));
    }
}

Imports System
Imports System.Reflection
Imports Microsoft.VisualBasic

Public Class MyFieldClassA
    Public Field As String = "A Field"
End Class 'MyFieldClassA

Public Class MyFieldClassB
    Private myField As String = "B Field"

    Public Property Field() As String
        Get
            Return myField
        End Get
        Set(ByVal Value As String)
            If myField <> value Then
                myField = value
            End If
        End Set
    End Property
End Class 'MyFieldClassB


Public Class MyFieldInfoClass

    Public Shared Sub Main()
        Dim myFieldObjectB As New MyFieldClassB()
        Dim myFieldObjectA As New MyFieldClassA()

        Dim myTypeA As Type = GetType(MyFieldClassA)
        Dim myFieldInfo As FieldInfo = myTypeA.GetField("Field")

        Dim myTypeB As Type = GetType(MyFieldClassB)
        Dim myFieldInfo1 As FieldInfo = myTypeB.GetField("myField", _
            BindingFlags.NonPublic Or BindingFlags.Instance)

        Console.WriteLine("The value of the public field is: '{0}'", _
            myFieldInfo.GetValue(myFieldObjectA))
        Console.WriteLine("The value of the private field is: '{0}'", _
            myFieldInfo1.GetValue(myFieldObjectB))
    End Sub 'Main

End Class 'MyFieldInfoClass

注解

搜索name区分大小写。The search for name is case-sensitive. 搜索中包括公共静态和公共实例字段。The search includes public static and public instance fields.

如果当前Type表示构造泛型类型,此方法返回FieldInfo具有类型参数替换为适当的类型参数。If the current Type represents a constructed generic type, this method returns the FieldInfo with the type parameters replaced by the appropriate type arguments.

如果当前Type表示的类型参数的泛型类型或泛型方法定义中,在此方法搜索类约束的字段。If the current Type represents a type parameter in the definition of a generic type or generic method, this method searches the fields of the class constraint.

另请参阅

GetField(String, BindingFlags) GetField(String, BindingFlags) GetField(String, BindingFlags) GetField(String, BindingFlags)

使用指定绑定约束搜索指定字段。Searches for the specified field, using the specified binding constraints.

public:
 abstract System::Reflection::FieldInfo ^ GetField(System::String ^ name, System::Reflection::BindingFlags bindingAttr);
public abstract System.Reflection.FieldInfo GetField (string name, System.Reflection.BindingFlags bindingAttr);
abstract member GetField : string * System.Reflection.BindingFlags -> System.Reflection.FieldInfo
Public MustOverride Function GetField (name As String, bindingAttr As BindingFlags) As FieldInfo

参数

name
String String String String

包含要获取的数据字段的名称的字符串。The string containing the name of the data field to get.

bindingAttr
BindingFlags BindingFlags BindingFlags BindingFlags

枚举值的按位组合,这些值指定如何进行搜索。A bitwise combination of the enumeration values that specify how the search is conducted.

- 或 --or- 若为 Default,则返回 nullDefault to return null.

返回

表示符合指定需求的字段的对象(如果找到的话);否则为 nullAn object representing the field that matches the specified requirements, if found; otherwise, null.

实现

异常

示例

下面的示例获取Type指定的类对象,获取FieldInfo匹配指定的绑定标志,并显示字段的值的字段的对象。The following example gets the Type object for the specified class, obtains the FieldInfo object for the field that matches the specified binding flags, and displays the value of the field.

using namespace System;
using namespace System::Reflection;
using namespace System::Security;
public ref class MyFieldClassA
{
public:
   String^ field;
   MyFieldClassA()
   {
      field = "A Field";
   }


   property String^ Field 
   {
      String^ get()
      {
         return field;
      }

      void set( String^ value )
      {
         if ( field != value )
         {
            field = value;
         }
      }

   }

};

public ref class MyFieldClassB
{
public:
   String^ field;
   MyFieldClassB()
   {
      field = "B Field";
   }


   property String^ Field 
   {
      String^ get()
      {
         return field;
      }

      void set( String^ value )
      {
         if ( field != value )
         {
            field = value;
         }
      }

   }

};

int main()
{
   try
   {
      MyFieldClassB^ myFieldObjectB = gcnew MyFieldClassB;
      MyFieldClassA^ myFieldObjectA = gcnew MyFieldClassA;
      Type^ myTypeA = Type::GetType( "MyFieldClassA" );
      FieldInfo^ myFieldInfo = myTypeA->GetField( "field" );
      Type^ myTypeB = Type::GetType( "MyFieldClassB" );
      FieldInfo^ myFieldInfo1 = myTypeB->GetField( "field", static_cast<BindingFlags>(BindingFlags::Public | BindingFlags::Instance) );
      Console::WriteLine( "The value of the field is : {0} ", myFieldInfo->GetValue( myFieldObjectA ) );
      Console::WriteLine( "The value of the field is : {0} ", myFieldInfo1->GetValue( myFieldObjectB ) );
   }
   catch ( SecurityException^ e ) 
   {
      Console::WriteLine( "Exception Raised!" );
      Console::WriteLine( "Message : {0}", e->Message );
   }
   catch ( ArgumentNullException^ e ) 
   {
      Console::WriteLine( "Exception Raised!" );
      Console::WriteLine( "Message : {0}", e->Message );
   }
   catch ( Exception^ e ) 
   {
      Console::WriteLine( "Exception Raised!" );
      Console::WriteLine( "Message : {0}", e->Message );
   }

}


using System;
using System.Reflection;

public class MyFieldClassA
{
    public string Field = "A Field";
}

public class MyFieldClassB
{
    private string field = "B Field";
    public string Field 
    {
        get
        {
            return field;
        }
        set
        {
            if (field!=value)
            {
                field=value;
            }
        }
    }
}

public class MyFieldInfoClass
{
    public static void Main()
    {
        MyFieldClassB myFieldObjectB = new MyFieldClassB();
        MyFieldClassA myFieldObjectA = new MyFieldClassA();

        Type myTypeA = typeof(MyFieldClassA);
        FieldInfo myFieldInfo = myTypeA.GetField("Field");

        Type myTypeB = typeof(MyFieldClassB);
        FieldInfo myFieldInfo1 = myTypeB.GetField("field", 
            BindingFlags.NonPublic | BindingFlags.Instance);

        Console.WriteLine("The value of the public field is: '{0}'", 
            myFieldInfo.GetValue(myFieldObjectA));
        Console.WriteLine("The value of the private field is: '{0}'", 
            myFieldInfo1.GetValue(myFieldObjectB));
    }
}

Imports System
Imports System.Reflection
Imports Microsoft.VisualBasic

Public Class MyFieldClassA
    Public Field As String = "A Field"
End Class 'MyFieldClassA

Public Class MyFieldClassB
    Private myField As String = "B Field"

    Public Property Field() As String
        Get
            Return myField
        End Get
        Set(ByVal Value As String)
            If myField <> value Then
                myField = value
            End If
        End Set
    End Property
End Class 'MyFieldClassB


Public Class MyFieldInfoClass

    Public Shared Sub Main()
        Dim myFieldObjectB As New MyFieldClassB()
        Dim myFieldObjectA As New MyFieldClassA()

        Dim myTypeA As Type = GetType(MyFieldClassA)
        Dim myFieldInfo As FieldInfo = myTypeA.GetField("Field")

        Dim myTypeB As Type = GetType(MyFieldClassB)
        Dim myFieldInfo1 As FieldInfo = myTypeB.GetField("myField", _
            BindingFlags.NonPublic Or BindingFlags.Instance)

        Console.WriteLine("The value of the public field is: '{0}'", _
            myFieldInfo.GetValue(myFieldObjectA))
        Console.WriteLine("The value of the private field is: '{0}'", _
            myFieldInfo1.GetValue(myFieldObjectB))
    End Sub 'Main

End Class 'MyFieldInfoClass

注解

下表显示了返回通过基类的成员Get方法反射的类型上时。The following table shows what members of a base class are returned by the Get methods when reflecting on a type.

成员类型Member Type StaticStatic 非静态Non-Static
构造函数Constructor NoNo NoNo
字段Field NoNo 可以。Yes. 字段始终是按名称和签名隐藏。A field is always hide-by-name-and-signature.
事件Event 不适用Not applicable 通用类型系统规则是继承是实现的属性的方法相同。The common type system rule is that the inheritance is the same as that of the methods that implement the property. 反射将属性视为由名称和签名隐藏。Reflection treats properties as hide-by-name-and-signature. 请参阅备注 2 下面。See note 2 below.
方法Method NoNo 可以。Yes. 方法 (包括虚拟和非虚拟) 可以隐藏通过名称或按名称和签名隐藏。A method (both virtual and non-virtual) can be hide-by-name or hide-by-name-and-signature.
嵌套的类型Nested Type NoNo NoNo
PropertyProperty 不适用Not applicable 通用类型系统规则是继承是实现的属性的方法相同。The common type system rule is that the inheritance is the same as that of the methods that implement the property. 反射将属性视为由名称和签名隐藏。Reflection treats properties as hide-by-name-and-signature. 请参阅备注 2 下面。See note 2 below.
  1. 按名称和签名隐藏会考虑所有的签名,包括自定义修饰符,部分返回类型、 参数类型、 标记和非托管调用约定。Hide-by-name-and-signature considers all of the parts of the signature, including custom modifiers, return types, parameter types, sentinels, and unmanaged calling conventions. 这是二进制比较。This is a binary comparison.

  2. 为反射,属性和事件均由名称和签名隐藏。For reflection, properties and events are hide-by-name-and-signature. 如果具有 get 和 set 访问器的属性中的基类,但派生的类具有一个 get 访问器,派生的类属性隐藏基类属性,并且你将无法再访问基类上的资源库。If you have a property with both a get and a set accessor in the base class, but the derived class has only a get accessor, the derived class property hides the base class property, and you will not be able to access the setter on the base class.

  3. 自定义特性不是通用类型系统的一部分。Custom attributes are not part of the common type system.

以下BindingFlags的筛选器标志可以用于定义要在搜索中包括哪些字段:The following BindingFlags filter flags can be used to define which fields to include in the search:

  • 您必须指定这两BindingFlags.InstanceBindingFlags.Static为了获取返回。You must specify either BindingFlags.Instance or BindingFlags.Static in order to get a return.

  • 指定BindingFlags.Public若要在搜索中包括公共字段。Specify BindingFlags.Public to include public fields in the search.

  • 指定BindingFlags.NonPublic若要在搜索中包括非公共字段 (即私有、 内部和受保护字段)。Specify BindingFlags.NonPublic to include non-public fields (that is, private, internal, and protected fields) in the search.

  • 指定BindingFlags.FlattenHierarchy用以publicprotected层次结构; 上的静态成员private中继承的类的静态成员不包括。Specify BindingFlags.FlattenHierarchy to include public and protected static members up the hierarchy; private static members in inherited classes are not included.

以下BindingFlags修饰符标志可以用于更改搜索的工作原理:The following BindingFlags modifier flags can be used to change how the search works:

  • BindingFlags.IgnoreCase 若要忽略大小写的nameBindingFlags.IgnoreCase to ignore the case of name.

  • BindingFlags.DeclaredOnly 若要搜索仅上声明的字段Type,不只是继承的字段。BindingFlags.DeclaredOnly to search only the fields declared on the Type, not fields that were simply inherited.

有关更多信息,请参见System.Reflection.BindingFlagsSee System.Reflection.BindingFlags for more information.

如果当前Type表示构造泛型类型,此方法返回FieldInfo具有类型参数替换为适当的类型参数。If the current Type represents a constructed generic type, this method returns the FieldInfo with the type parameters replaced by the appropriate type arguments.

如果当前Type表示的类型参数的泛型类型或泛型方法定义中,在此方法搜索类约束的字段。If the current Type represents a type parameter in the definition of a generic type or generic method, this method searches the fields of the class constraint.

另请参阅

适用于