Attribute.IsDefined 方法

定义

命名空间:: System

程序集:: netstandard.dll, System.Runtime.dll

程序集:: System.Runtime.dll

程序集:: mscorlib.dll

程序集:: netstandard.dll

重要

一些信息与预发行产品相关，相应产品在发行之前可能会进行重大修改。对于此处提供的信息，Microsoft 不作任何明示或暗示的担保。

确定指定类型的任何自定义属性是否应用于程序集、模块、类型成员或方法参数。

重载

名称	说明
IsDefined(ParameterInfo, Type, Boolean)	确定是否将任何自定义属性应用于方法参数。参数指定要搜索的方法参数、要搜索的自定义属性的类型，以及是否搜索方法参数的上级。
IsDefined(Module, Type, Boolean)	确定是否将任何自定义属性应用于模块。参数指定要搜索的模块、要搜索的自定义属性的类型和忽略的搜索选项。
IsDefined(MemberInfo, Type, Boolean)	确定是否将任何自定义属性应用于类型的成员。参数指定要搜索的成员、要搜索的自定义属性的类型以及是否搜索成员的上级。
IsDefined(Assembly, Type, Boolean)	确定是否将任何自定义属性应用于程序集。参数指定要搜索的程序集、要搜索的自定义属性的类型和忽略的搜索选项。
IsDefined(MemberInfo, Type)	确定是否将任何自定义属性应用于类型的成员。参数指定要搜索的成员和自定义属性的类型。
IsDefined(Module, Type)	确定指定类型的任何自定义属性是否应用于模块。参数指定要搜索的模块和自定义属性的类型。
IsDefined(Assembly, Type)	确定是否将任何自定义属性应用于程序集。参数指定要搜索的程序集和自定义属性的类型。
IsDefined(ParameterInfo, Type)	确定是否将任何自定义属性应用于方法参数。参数指定要搜索的方法参数和自定义属性的类型。

IsDefined(ParameterInfo, Type, Boolean)

Source:: Attribute.CoreCLR.cs

Source:: Attribute.CoreCLR.cs

Source:: Attribute.CoreCLR.cs

Source:: Attribute.CoreCLR.cs

Source:: Attribute.CoreCLR.cs

确定是否将任何自定义属性应用于方法参数。参数指定要搜索的方法参数、要搜索的自定义属性的类型，以及是否搜索方法参数的上级。

public:
 static bool IsDefined(System::Reflection::ParameterInfo ^ element, Type ^ attributeType, bool inherit);

public static bool IsDefined(System.Reflection.ParameterInfo element, Type attributeType, bool inherit);

static member IsDefined : System.Reflection.ParameterInfo * Type * bool -> bool

Public Shared Function IsDefined (element As ParameterInfo, attributeType As Type, inherit As Boolean) As Boolean

参数

element: ParameterInfo

一个派生自 ParameterInfo 描述类成员的参数的类的对象。

attributeType: Type

要搜索的自定义属性的类型或基类型。

inherit: Boolean

如果 true指定，则还搜索自定义属性的 element 上级。

Boolean

如果应用于类型的自定义属性，则为 ;否则为 < a1/>。

例外

ArgumentNullException

element 或 attributeType 为 null.

ArgumentException

attributeType 不是派生自 Attribute.

ExecutionEngineException

element 不是方法、构造函数或类型。

示例

下面的代码示例演示了采用参数作为参数的IsDefined ParameterInfo用法。

using System;
using System.Reflection;

namespace IsDef5CS
{
    public class TestClass
    {
        // Assign a ParamArray attribute to the parameter using the keyword.
        public void Method1(params String[] args)
        {}
    }

    public class DemoClass
    {
        static void Main(string[] args)
        {
            // Get the class type to access its metadata.
            Type clsType = typeof(TestClass);
            // Get the MethodInfo object for Method1.
            MethodInfo mInfo = clsType.GetMethod("Method1");
            // Get the ParameterInfo array for the method parameters.
            ParameterInfo[] pInfo = mInfo.GetParameters();
            if (pInfo != null)
            {
                // See if the ParamArray attribute is defined.
                bool isDef = Attribute.IsDefined(pInfo[0],
                                                 typeof(ParamArrayAttribute));
                // Display the result.
                Console.WriteLine("The ParamArray attribute {0} defined for " +
                                  "parameter {1} of method {2}.",
                                  isDef ? "is" : "is not",
                                  pInfo[0].Name,
                                  mInfo.Name);
            }
            else
                Console.WriteLine("The parameters information could " +
                            "not be retrieved for method {0}.", mInfo.Name);
        }
    }
}

/*
 * Output:
 * The ParamArray attribute is defined for parameter args of method Method1.
 */

open System;

type TestClass() =
    // Assign a ParamArray attribute to the parameter.
    member _.Method1([<ParamArray>] args: string[]) = ()

// Get the class type to access its metadata.
let clsType = typeof<TestClass>

// Get the MethodInfo object for Method1.
let mInfo = clsType.GetMethod "Method1"

// Get the ParameterInfo array for the method parameters.
let pInfo = mInfo.GetParameters()

if pInfo <> null then
    // See if the ParamArray attribute is defined.
    let isDef = Attribute.IsDefined(pInfo[0], typeof<ParamArrayAttribute>)

    // Display the result.
    printfn $"""The ParamArray attribute {if isDef then "is" else "is not"} defined for parameter {pInfo[0].Name} of method {mInfo.Name}."""
else
    printfn $"The parameters information could not be retrieved for method {mInfo.Name}."

// Output:
//  The ParamArray attribute is defined for parameter args of method Method1.

Imports System.Reflection

Module DemoModule
    Public Class TestClass
        ' Assign a ParamArray attribute to the parameter using the keyword.
        Public Sub Method1(ByVal ParamArray args As String())
        End Sub
    End Class

    Sub Main()
        ' Get the class type to access its metadata.
        Dim clsType As Type = GetType(TestClass)
        ' Get the MethodInfo object for Method1.
        Dim mInfo As MethodInfo = clsType.GetMethod("Method1")
        ' Get the ParameterInfo array for the method parameters.
        Dim pInfo() As ParameterInfo = mInfo.GetParameters()
        If Not pInfo(0) Is Nothing Then
            ' See if the ParamArray attribute is defined.
            Dim isDef As Boolean = Attribute.IsDefined(pInfo(0), _
                                   GetType(ParamArrayAttribute))
            Dim strDef As String
            If isDef = True Then
                strDef = "is"
            Else
                strDef = "is not"
            End If
            ' Display the result.
            Console.WriteLine("The ParamArray attribute {0} defined " & _
                              "for parameter {1} of method {2}.", _
                              strDef, pInfo(0).Name, mInfo.Name)
        Else
            Console.WriteLine("Could not retrieve parameter information " & _
                              "for method {0}.", mInfo.Name)
        End If
    End Sub
End Module

' Output:
' The ParamArray attribute is defined for parameter args of method Method1.

适用于

IsDefined(Module, Type, Boolean)

Source:: Attribute.CoreCLR.cs

Source:: Attribute.CoreCLR.cs

Source:: Attribute.CoreCLR.cs

Source:: Attribute.CoreCLR.cs

Source:: Attribute.CoreCLR.cs

确定是否将任何自定义属性应用于模块。参数指定要搜索的模块、要搜索的自定义属性的类型和忽略的搜索选项。

public:
 static bool IsDefined(System::Reflection::Module ^ element, Type ^ attributeType, bool inherit);

public static bool IsDefined(System.Reflection.Module element, Type attributeType, bool inherit);

static member IsDefined : System.Reflection.Module * Type * bool -> bool

Public Shared Function IsDefined (element As Module, attributeType As Type, inherit As Boolean) As Boolean

参数

element: Module

一个派生自 Module 描述可移植可执行文件的类的对象。

attributeType: Type

要搜索的自定义属性的类型或基类型。

inherit: Boolean

忽略此参数，不会影响此方法的操作。

Boolean

如果应用于类型的自定义属性，则为 ;否则为 < a1/>。

例外

ArgumentNullException

element 或 attributeType 为 null.

ArgumentException

attributeType 不是派生自 Attribute.

示例

下面的代码示例演示了采用参数作为参数的IsDefined Module用法。

using System;
using System.Diagnostics;

// Add the Debuggable attribute to the module.
[module:Debuggable(true, false)]
namespace IsDef2CS
{
    public class DemoClass
    {
        static void Main(string[] args)
        {
            // Get the class type to access its metadata.
            Type clsType = typeof(DemoClass);
            // See if the Debuggable attribute is defined for this module.
            bool isDef = Attribute.IsDefined(clsType.Module,
                typeof(DebuggableAttribute));
            // Display the result.
            Console.WriteLine("The Debuggable attribute {0} " +
                "defined for Module {1}.",
                isDef ? "is" : "is not",
                clsType.Module.Name);
            // If the attribute is defined, display the JIT settings.
            if (isDef)
            {
                // Retrieve the attribute itself.
                DebuggableAttribute dbgAttr = (DebuggableAttribute)
                    Attribute.GetCustomAttribute(clsType.Module,
                    typeof(DebuggableAttribute));
                if (dbgAttr != null)
                {
                    Console.WriteLine("JITTrackingEnabled is {0}.",
                        dbgAttr.IsJITTrackingEnabled);
                    Console.WriteLine("JITOptimizerDisabled is {0}.",
                        dbgAttr.IsJITOptimizerDisabled);
                }
                else
                    Console.WriteLine("The Debuggable attribute " +
                        "could not be retrieved.");
            }
        }
    }
}

/*
 * Output:
 * The Debuggable attribute is defined for Module IsDef2CS.exe.
 * JITTrackingEnabled is True.
 * JITOptimizerDisabled is False.
 */

open System
open System.Diagnostics

// Add the Debuggable attribute to the module.
[<``module``: Debuggable(true, false)>]
do ()
    
type DemoClass = class end

// Get the class type to access its metadata.
let clsType = typeof<DemoClass>

// See if the Debuggable attribute is defined for this module.
let isDef = Attribute.IsDefined(clsType.Module, typeof<DebuggableAttribute>)

// Display the result.
printfn $"""The Debuggable attribute {if isDef then "is" else "is not"} defined for Module {clsType.Module.Name}."""

// If the attribute is defined, display the JIT settings.
if isDef then
    // Retrieve the attribute itself.
    let dbgAttr =
        Attribute.GetCustomAttribute(clsType.Module, typeof<DebuggableAttribute>)
        :?> DebuggableAttribute

    if dbgAttr <> null then
        printfn $"JITTrackingEnabled is {dbgAttr.IsJITTrackingEnabled}."
        printfn $"JITOptimizerDisabled is {dbgAttr.IsJITOptimizerDisabled}."            
    else
        printfn "The Debuggable attribute could not be retrieved."

// Output:
//  The Debuggable attribute is defined for Module IsDef2CS.exe.
//  JITTrackingEnabled is True.
//  JITOptimizerDisabled is False.

Imports System.Reflection
Imports System.Diagnostics

' Add the Debuggable attribute to the module.
<Module: Debuggable(True, False)> 

Module DemoModule
    Sub Main()
        ' Get the module type information to access its metadata.
        Dim modType As Type = GetType(DemoModule)
        ' See if the Debuggable attribute is defined.
        Dim isDef As Boolean = Attribute.IsDefined(modType.Module, _
                               GetType(DebuggableAttribute))
        Dim strDef As String
        If isDef = True Then
            strDef = "is"
        Else
            strDef = "is not"
        End If
        ' Display the result
        Console.WriteLine("The debuggable attribute {0} defined for " & _
                          "module {1}.", strDef, modType.Name)
        ' If the attribute is defined, display the JIT settings.
        If isDef = True Then
            ' Retrieve the attribute itself.
            Dim attr As Attribute = _
                Attribute.GetCustomAttribute(modType.Module, _
                GetType(DebuggableAttribute))
            If Not attr Is Nothing And TypeOf attr Is DebuggableAttribute Then
                Dim dbgAttr As DebuggableAttribute = _
                    CType(attr, DebuggableAttribute)
                Console.WriteLine("JITTrackingEnabled is {0}.", _
                    dbgAttr.IsJITTrackingEnabled.ToString())
                Console.WriteLine("JITOptimizerDisabled is {0}.", _
                    dbgAttr.IsJITOptimizerDisabled.ToString())
            Else
                Console.WriteLine("The Debuggable attribute could " & _
                                  "not be retrieved.")
            End If
        End If
    End Sub
End Module

' Output:
' The debuggable attribute is defined for module DemoModule.
' JITTrackingEnabled is True.
' JITOptimizerDisabled is False.

注解

此方法忽略参数 inherit ，不搜索自定义属性的 element 上级。

适用于

IsDefined(MemberInfo, Type, Boolean)

Source:: Attribute.CoreCLR.cs

Source:: Attribute.CoreCLR.cs

Source:: Attribute.CoreCLR.cs

Source:: Attribute.CoreCLR.cs

Source:: Attribute.CoreCLR.cs

确定是否将任何自定义属性应用于类型的成员。参数指定要搜索的成员、要搜索的自定义属性的类型以及是否搜索成员的上级。

public:
 static bool IsDefined(System::Reflection::MemberInfo ^ element, Type ^ attributeType, bool inherit);

public static bool IsDefined(System.Reflection.MemberInfo element, Type attributeType, bool inherit);

static member IsDefined : System.Reflection.MemberInfo * Type * bool -> bool

Public Shared Function IsDefined (element As MemberInfo, attributeType As Type, inherit As Boolean) As Boolean

参数

element: MemberInfo

从 MemberInfo 类派生的对象，该类描述类的构造函数、事件、字段、方法、类型或属性成员。

attributeType: Type

要搜索的自定义属性的类型或基类型。

inherit: Boolean

如果 true指定，则还搜索自定义属性的 element 上级。

Boolean

如果应用于类型的自定义属性，则为 ;否则为 < a1/>。

例外

ArgumentNullException

element 或 attributeType 为 null.

ArgumentException

attributeType 不是派生自 Attribute.

NotSupportedException

element 不是构造函数、方法、属性、事件、类型或字段。

示例

下面的代码示例演示了采用参数作为参数的IsDefined MemberInfo用法。

using System;
using System.Reflection;

namespace IsDef4CS
{
    public class TestClass
    {
        // Assign the Obsolete attribute to a method.
        [Obsolete("This method is obsolete. Use Method2 instead.")]
        public void Method1()
        {}
        public void Method2()
        {}
    }

    public class DemoClass
    {
        static void Main(string[] args)
        {
            // Get the class type to access its metadata.
            Type clsType = typeof(TestClass);
            // Get the MethodInfo object for Method1.
            MethodInfo mInfo = clsType.GetMethod("Method1");
            // See if the Obsolete attribute is defined for this method.
            bool isDef = Attribute.IsDefined(mInfo, typeof(ObsoleteAttribute));
            // Display the result.
            Console.WriteLine("The Obsolete Attribute {0} defined for {1} of class {2}.",
                isDef ? "is" : "is not", mInfo.Name, clsType.Name);
            // If it's defined, display the attribute's message.
            if (isDef)
            {
                ObsoleteAttribute obsAttr =
                                 (ObsoleteAttribute)Attribute.GetCustomAttribute(
                                                    mInfo, typeof(ObsoleteAttribute));
                if (obsAttr != null)
                    Console.WriteLine("The message is: \"{0}\".",
                        obsAttr.Message);
                else
                    Console.WriteLine("The message could not be retrieved.");
            }
        }
    }
}

/*
 * Output:
 * The Obsolete Attribute is defined for Method1 of class TestClass.
 * The message is: "This method is obsolete. Use Method2 instead.".
 */

open System

type TestClass() =
    // Assign the Obsolete attribute to a method.
    [<Obsolete "This method is obsolete. Use Method2 instead.">]
    member _.Method1() = ()
    member _.Method2() = ()

// Get the class type to access its metadata.
let clsType = typeof<TestClass>

// Get the MethodInfo object for Method1.
let mInfo = clsType.GetMethod "Method1"

// See if the Obsolete attribute is defined for this method.
let isDef = Attribute.IsDefined(mInfo, typeof<ObsoleteAttribute>)

// Display the result.
printfn $"""The Obsolete Attribute {if isDef then "is" else "is not"} defined for {mInfo.Name} of class {clsType.Name}."""

// If it's defined, display the attribute's message.
if isDef then
    let obsAttr =
        Attribute.GetCustomAttribute(mInfo, typeof<ObsoleteAttribute>)
        :?> ObsoleteAttribute
    if obsAttr <> null then
        printfn $"The message is: \"{obsAttr.Message}\"."
    else
        printfn "The message could not be retrieved."

// Output:
//  The Obsolete Attribute is defined for Method1 of class TestClass.
// The message is: "This method is obsolete. Use Method2 instead.".

Imports System.Reflection

Module DemoModule

    Public Class TestClass
        ' Assign the Obsolete attribute to a method.
        <Obsolete("This method is obsolete. Use Method2() instead.")> _
        Public Sub Method1()
        End Sub

        Public Sub Method2()
        End Sub
    End Class

    Sub Main()
        ' Get the class type to access its metadata.
        Dim clsType As Type = GetType(TestClass)
        ' Get the MethodInfo object for Method1.
        Dim mInfo As MethodInfo = clsType.GetMethod("Method1")
        ' See if the Obsolete attribute is defined for this method.
        Dim isDef As Boolean = Attribute.IsDefined(mInfo, _
            GetType(ObsoleteAttribute))
        Dim strDef As String
        If isDef = True Then
            strDef = "is"
        Else
            strDef = "is not"
        End If
        ' Display the results.
        Console.WriteLine("The Obsolete attribute {0} defined for " & _
            "method {1} of class {2}.", strDef, mInfo.Name, clsType.Name)
        ' If it's defined, display the attribute's message.
        If isDef = True Then
            Dim attr As Attribute = Attribute.GetCustomAttribute(mInfo, _
                GetType(ObsoleteAttribute))
            If Not attr Is Nothing And TypeOf attr Is ObsoleteAttribute Then
                Dim obsAttr As ObsoleteAttribute = _
                    CType(attr, ObsoleteAttribute)
                Console.WriteLine("The message is: ""{0}""", obsAttr.Message)
            Else
                Console.WriteLine("The message could not be retrieved.")
            End If
        End If
    End Sub
End Module

' Output:
' The Obsolete attribute is defined for method Method1 of class TestClass.
' The message is: "This method is obsolete. Use Method2() instead."

注解

注释

从 .NET Framework 版本 2.0 开始，如果类型、方法或构造函数具有以新元数据格式存储的安全属性，此方法将返回 true。使用版本 2.0 或更高版本编译的程序集使用新格式。

适用于

IsDefined(Assembly, Type, Boolean)

Source:: Attribute.CoreCLR.cs

Source:: Attribute.CoreCLR.cs

Source:: Attribute.CoreCLR.cs

Source:: Attribute.CoreCLR.cs

Source:: Attribute.CoreCLR.cs

确定是否将任何自定义属性应用于程序集。参数指定要搜索的程序集、要搜索的自定义属性的类型和忽略的搜索选项。

public:
 static bool IsDefined(System::Reflection::Assembly ^ element, Type ^ attributeType, bool inherit);

public static bool IsDefined(System.Reflection.Assembly element, Type attributeType, bool inherit);

static member IsDefined : System.Reflection.Assembly * Type * bool -> bool

Public Shared Function IsDefined (element As Assembly, attributeType As Type, inherit As Boolean) As Boolean

参数

element: Assembly

一个派生自 Assembly 描述模块可重用集合的类的对象。

attributeType: Type

要搜索的自定义属性的类型或基类型。

inherit: Boolean

忽略此参数，不会影响此方法的操作。

Boolean

如果应用于类型的自定义属性，则为 ;否则为 < a1/>。

例外

ArgumentNullException

element 或 attributeType 为 null.

ArgumentException

attributeType 不是派生自 Attribute.

示例

下面的代码示例演示了采用参数作为参数的IsDefined Assembly用法。

using System;
using System.Reflection;

// Add an AssemblyDescription attribute
[assembly: AssemblyDescription("A sample description")]
namespace IsDef1CS
{
    public class DemoClass
    {
        static void Main(string[] args)
        {
            // Get the class type to access its metadata.
            Type clsType = typeof(DemoClass);
            // Get the assembly object.
            Assembly assy = clsType.Assembly;
            // Store the assembly's name.
            String assyName = assy.GetName().Name;
            // See if the Assembly Description is defined.
            bool isdef = Attribute.IsDefined(assy,
                typeof(AssemblyDescriptionAttribute));
            if (isdef)
            {
                // Affirm that the attribute is defined.
                Console.WriteLine("The AssemblyDescription attribute " +
                    "is defined for assembly {0}.", assyName);
                // Get the description attribute itself.
                AssemblyDescriptionAttribute adAttr =
                    (AssemblyDescriptionAttribute)Attribute.GetCustomAttribute(
                    assy, typeof(AssemblyDescriptionAttribute));
                // Display the description.
                if (adAttr != null)
                    Console.WriteLine("The description is \"{0}\".",
                        adAttr.Description);
                else
                    Console.WriteLine("The description could not " +
                        "be retrieved.");
            }
            else
                Console.WriteLine("The AssemblyDescription attribute is not " +
                    "defined for assembly {0}.", assyName);
        }
    }
}

/*
 * Output:
 * The AssemblyDescription attribute is defined for assembly IsDef1CS.
 * The description is "A sample description".
 */

open System
open System.Reflection

// Add an AssemblyDescription attribute
[<assembly: AssemblyDescription "A sample description">]
do ()

type DemoClass = class end

// Get the class type to access its metadata.
let clsType = typeof<DemoClass>

// Get the assembly object.
let assembly = clsType.Assembly;

// Store the assembly's name.
let assemblyName = assembly.GetName().Name

// See if the Assembly Description is defined.
let isdef = 
    Attribute.IsDefined(assembly, typeof<AssemblyDescriptionAttribute>)

if isdef then
    // Affirm that the attribute is defined.
    printfn $"The AssemblyDescription attribute is defined for assembly {assemblyName}."
    
    // Get the description attribute itself.
    let adAttr =
        Attribute.GetCustomAttribute(assembly, typeof<AssemblyDescriptionAttribute>)
        :?> AssemblyDescriptionAttribute

    // Display the description.
    if adAttr <> null then
        printfn $"The description is \"{adAttr.Description}\"."
    else
        printfn $"The description could not be retrieved."
else
    printfn $"The AssemblyDescription attribute is not defined for assembly {assemblyName}."

// Output:
//  The AssemblyDescription attribute is defined for assembly IsDef1FS.
//  The description is "A sample description".

Imports System.Reflection

' Add an AssemblyDescription attribute.
<Assembly: AssemblyDescription("A sample description")> 

Module DemoModule
    Sub Main()
        ' Get the assembly for this module.
        Dim assy As System.Reflection.Assembly = GetType(DemoModule).Assembly
        ' Store the assembly name.
        Dim assyName As String = assy.GetName().Name
        ' See if the AssemblyDescription attribute is defined.
        If Attribute.IsDefined(assy, GetType(AssemblyDescriptionAttribute)) _
            Then
            ' Affirm that the attribute is defined. Assume the filename of
            ' this code example is "IsDef1VB".
            Console.WriteLine("The AssemblyDescription attribute is " & _
                "defined for assembly {0}.", assyName)
            ' Get the description attribute itself.
            Dim attr As Attribute = Attribute.GetCustomAttribute( _
                assy, GetType(AssemblyDescriptionAttribute))
            ' Display the description.
            If Not attr Is Nothing And _
                TypeOf attr Is AssemblyDescriptionAttribute Then
                Dim adAttr As AssemblyDescriptionAttribute = _
                    CType(attr, AssemblyDescriptionAttribute)
                Console.WriteLine("The description is " & _
                    Chr(34) & "{0}" & Chr(34) & ".", adAttr.Description)
            Else
                Console.WriteLine("The description could not be retrieved.")
            End If
        Else
            Console.WriteLine("The AssemblyDescription attribute is not " & _
                              "defined for assembly {0}.", assyName)
        End If
    End Sub
End Module

' Output:
' The AssemblyDescription attribute is defined for assembly IsDef1VB.
' The description is "A sample description".

注解

注释

从 .NET Framework 版本 2.0 开始，如果程序集具有以新元数据格式存储的安全属性，此方法将返回 true。使用版本 2.0 或更高版本编译的程序集使用新格式。

适用于

IsDefined(MemberInfo, Type)

Source:: Attribute.CoreCLR.cs

Source:: Attribute.CoreCLR.cs

Source:: Attribute.CoreCLR.cs

Source:: Attribute.CoreCLR.cs

Source:: Attribute.CoreCLR.cs

确定是否将任何自定义属性应用于类型的成员。参数指定要搜索的成员和自定义属性的类型。

public:
 static bool IsDefined(System::Reflection::MemberInfo ^ element, Type ^ attributeType);

public static bool IsDefined(System.Reflection.MemberInfo element, Type attributeType);

static member IsDefined : System.Reflection.MemberInfo * Type -> bool

Public Shared Function IsDefined (element As MemberInfo, attributeType As Type) As Boolean

参数

element: MemberInfo

从 MemberInfo 类派生的对象，该类描述类的构造函数、事件、字段、方法、类型或属性成员。

attributeType: Type

要搜索的自定义属性的类型或基类型。

Boolean

如果应用于类型的自定义属性，则为 ;否则为 < a1/>。

例外

ArgumentNullException

element 或 attributeType 为 null.

ArgumentException

attributeType 不是派生自 Attribute.

NotSupportedException

element 不是构造函数、方法、属性、事件、类型或字段。

示例

下面的代码示例演示了采用参数作为参数的IsDefined MemberInfo用法。

using System;
using System.Reflection;

namespace IsDef4CS
{
    public class TestClass
    {
        // Assign the Obsolete attribute to a method.
        [Obsolete("This method is obsolete. Use Method2 instead.")]
        public void Method1()
        {}
        public void Method2()
        {}
    }

    public class DemoClass
    {
        static void Main(string[] args)
        {
            // Get the class type to access its metadata.
            Type clsType = typeof(TestClass);
            // Get the MethodInfo object for Method1.
            MethodInfo mInfo = clsType.GetMethod("Method1");
            // See if the Obsolete attribute is defined for this method.
            bool isDef = Attribute.IsDefined(mInfo, typeof(ObsoleteAttribute));
            // Display the result.
            Console.WriteLine("The Obsolete Attribute {0} defined for {1} of class {2}.",
                isDef ? "is" : "is not", mInfo.Name, clsType.Name);
            // If it's defined, display the attribute's message.
            if (isDef)
            {
                ObsoleteAttribute obsAttr =
                                 (ObsoleteAttribute)Attribute.GetCustomAttribute(
                                                    mInfo, typeof(ObsoleteAttribute));
                if (obsAttr != null)
                    Console.WriteLine("The message is: \"{0}\".",
                        obsAttr.Message);
                else
                    Console.WriteLine("The message could not be retrieved.");
            }
        }
    }
}

/*
 * Output:
 * The Obsolete Attribute is defined for Method1 of class TestClass.
 * The message is: "This method is obsolete. Use Method2 instead.".
 */

open System

type TestClass() =
    // Assign the Obsolete attribute to a method.
    [<Obsolete "This method is obsolete. Use Method2 instead.">]
    member _.Method1() = ()
    member _.Method2() = ()

// Get the class type to access its metadata.
let clsType = typeof<TestClass>

// Get the MethodInfo object for Method1.
let mInfo = clsType.GetMethod "Method1"

// See if the Obsolete attribute is defined for this method.
let isDef = Attribute.IsDefined(mInfo, typeof<ObsoleteAttribute>)

// Display the result.
printfn $"""The Obsolete Attribute {if isDef then "is" else "is not"} defined for {mInfo.Name} of class {clsType.Name}."""

// If it's defined, display the attribute's message.
if isDef then
    let obsAttr =
        Attribute.GetCustomAttribute(mInfo, typeof<ObsoleteAttribute>)
        :?> ObsoleteAttribute
    if obsAttr <> null then
        printfn $"The message is: \"{obsAttr.Message}\"."
    else
        printfn "The message could not be retrieved."

// Output:
//  The Obsolete Attribute is defined for Method1 of class TestClass.
// The message is: "This method is obsolete. Use Method2 instead.".

Imports System.Reflection

Module DemoModule

    Public Class TestClass
        ' Assign the Obsolete attribute to a method.
        <Obsolete("This method is obsolete. Use Method2() instead.")> _
        Public Sub Method1()
        End Sub

        Public Sub Method2()
        End Sub
    End Class

    Sub Main()
        ' Get the class type to access its metadata.
        Dim clsType As Type = GetType(TestClass)
        ' Get the MethodInfo object for Method1.
        Dim mInfo As MethodInfo = clsType.GetMethod("Method1")
        ' See if the Obsolete attribute is defined for this method.
        Dim isDef As Boolean = Attribute.IsDefined(mInfo, _
            GetType(ObsoleteAttribute))
        Dim strDef As String
        If isDef = True Then
            strDef = "is"
        Else
            strDef = "is not"
        End If
        ' Display the results.
        Console.WriteLine("The Obsolete attribute {0} defined for " & _
            "method {1} of class {2}.", strDef, mInfo.Name, clsType.Name)
        ' If it's defined, display the attribute's message.
        If isDef = True Then
            Dim attr As Attribute = Attribute.GetCustomAttribute(mInfo, _
                GetType(ObsoleteAttribute))
            If Not attr Is Nothing And TypeOf attr Is ObsoleteAttribute Then
                Dim obsAttr As ObsoleteAttribute = _
                    CType(attr, ObsoleteAttribute)
                Console.WriteLine("The message is: ""{0}""", obsAttr.Message)
            Else
                Console.WriteLine("The message could not be retrieved.")
            End If
        End If
    End Sub
End Module

' Output:
' The Obsolete attribute is defined for method Method1 of class TestClass.
' The message is: "This method is obsolete. Use Method2() instead."

注解

搜索自定义属性的 element 上级。

注释

适用于

IsDefined(Module, Type)

Source:: Attribute.CoreCLR.cs

Source:: Attribute.CoreCLR.cs

Source:: Attribute.CoreCLR.cs

Source:: Attribute.CoreCLR.cs

Source:: Attribute.CoreCLR.cs

确定指定类型的任何自定义属性是否应用于模块。参数指定要搜索的模块和自定义属性的类型。

public:
 static bool IsDefined(System::Reflection::Module ^ element, Type ^ attributeType);

public static bool IsDefined(System.Reflection.Module element, Type attributeType);

static member IsDefined : System.Reflection.Module * Type -> bool

Public Shared Function IsDefined (element As Module, attributeType As Type) As Boolean

参数

element: Module

一个派生自 Module 描述可移植可执行文件的类的对象。

attributeType: Type

要搜索的自定义属性的类型或基类型。

Boolean

如果应用于类型的自定义属性，则为 ;否则为 < a1/>。

例外

ArgumentNullException

element 或 attributeType 为 null.

ArgumentException

attributeType 不是派生自 Attribute.

示例

下面的代码示例演示了采用参数作为参数的IsDefined Module用法。

using System;
using System.Diagnostics;

// Add the Debuggable attribute to the module.
[module:Debuggable(true, false)]
namespace IsDef2CS
{
    public class DemoClass
    {
        static void Main(string[] args)
        {
            // Get the class type to access its metadata.
            Type clsType = typeof(DemoClass);
            // See if the Debuggable attribute is defined for this module.
            bool isDef = Attribute.IsDefined(clsType.Module,
                typeof(DebuggableAttribute));
            // Display the result.
            Console.WriteLine("The Debuggable attribute {0} " +
                "defined for Module {1}.",
                isDef ? "is" : "is not",
                clsType.Module.Name);
            // If the attribute is defined, display the JIT settings.
            if (isDef)
            {
                // Retrieve the attribute itself.
                DebuggableAttribute dbgAttr = (DebuggableAttribute)
                    Attribute.GetCustomAttribute(clsType.Module,
                    typeof(DebuggableAttribute));
                if (dbgAttr != null)
                {
                    Console.WriteLine("JITTrackingEnabled is {0}.",
                        dbgAttr.IsJITTrackingEnabled);
                    Console.WriteLine("JITOptimizerDisabled is {0}.",
                        dbgAttr.IsJITOptimizerDisabled);
                }
                else
                    Console.WriteLine("The Debuggable attribute " +
                        "could not be retrieved.");
            }
        }
    }
}

/*
 * Output:
 * The Debuggable attribute is defined for Module IsDef2CS.exe.
 * JITTrackingEnabled is True.
 * JITOptimizerDisabled is False.
 */

open System
open System.Diagnostics

// Add the Debuggable attribute to the module.
[<``module``: Debuggable(true, false)>]
do ()
    
type DemoClass = class end

// Get the class type to access its metadata.
let clsType = typeof<DemoClass>

// See if the Debuggable attribute is defined for this module.
let isDef = Attribute.IsDefined(clsType.Module, typeof<DebuggableAttribute>)

// Display the result.
printfn $"""The Debuggable attribute {if isDef then "is" else "is not"} defined for Module {clsType.Module.Name}."""

// If the attribute is defined, display the JIT settings.
if isDef then
    // Retrieve the attribute itself.
    let dbgAttr =
        Attribute.GetCustomAttribute(clsType.Module, typeof<DebuggableAttribute>)
        :?> DebuggableAttribute

    if dbgAttr <> null then
        printfn $"JITTrackingEnabled is {dbgAttr.IsJITTrackingEnabled}."
        printfn $"JITOptimizerDisabled is {dbgAttr.IsJITOptimizerDisabled}."            
    else
        printfn "The Debuggable attribute could not be retrieved."

// Output:
//  The Debuggable attribute is defined for Module IsDef2CS.exe.
//  JITTrackingEnabled is True.
//  JITOptimizerDisabled is False.

Imports System.Reflection
Imports System.Diagnostics

' Add the Debuggable attribute to the module.
<Module: Debuggable(True, False)> 

Module DemoModule
    Sub Main()
        ' Get the module type information to access its metadata.
        Dim modType As Type = GetType(DemoModule)
        ' See if the Debuggable attribute is defined.
        Dim isDef As Boolean = Attribute.IsDefined(modType.Module, _
                               GetType(DebuggableAttribute))
        Dim strDef As String
        If isDef = True Then
            strDef = "is"
        Else
            strDef = "is not"
        End If
        ' Display the result
        Console.WriteLine("The debuggable attribute {0} defined for " & _
                          "module {1}.", strDef, modType.Name)
        ' If the attribute is defined, display the JIT settings.
        If isDef = True Then
            ' Retrieve the attribute itself.
            Dim attr As Attribute = _
                Attribute.GetCustomAttribute(modType.Module, _
                GetType(DebuggableAttribute))
            If Not attr Is Nothing And TypeOf attr Is DebuggableAttribute Then
                Dim dbgAttr As DebuggableAttribute = _
                    CType(attr, DebuggableAttribute)
                Console.WriteLine("JITTrackingEnabled is {0}.", _
                    dbgAttr.IsJITTrackingEnabled.ToString())
                Console.WriteLine("JITOptimizerDisabled is {0}.", _
                    dbgAttr.IsJITOptimizerDisabled.ToString())
            Else
                Console.WriteLine("The Debuggable attribute could " & _
                                  "not be retrieved.")
            End If
        End If
    End Sub
End Module

' Output:
' The debuggable attribute is defined for module DemoModule.
' JITTrackingEnabled is True.
' JITOptimizerDisabled is False.

注解

不会搜索其祖先 element 的自定义属性。

适用于

IsDefined(Assembly, Type)

Source:: Attribute.CoreCLR.cs

Source:: Attribute.CoreCLR.cs

Source:: Attribute.CoreCLR.cs

Source:: Attribute.CoreCLR.cs

Source:: Attribute.CoreCLR.cs

确定是否将任何自定义属性应用于程序集。参数指定要搜索的程序集和自定义属性的类型。

public:
 static bool IsDefined(System::Reflection::Assembly ^ element, Type ^ attributeType);

public static bool IsDefined(System.Reflection.Assembly element, Type attributeType);

static member IsDefined : System.Reflection.Assembly * Type -> bool

Public Shared Function IsDefined (element As Assembly, attributeType As Type) As Boolean

参数

element: Assembly

一个派生自 Assembly 描述模块可重用集合的类的对象。

attributeType: Type

要搜索的自定义属性的类型或基类型。

Boolean

如果应用于类型的自定义属性，则为 ;否则为 < a1/>。

例外

ArgumentNullException

element 或 attributeType 为 null.

ArgumentException

attributeType 不是派生自 Attribute.

示例

下面的代码示例演示了采用参数作为参数的IsDefined Assembly用法。

using System;
using System.Reflection;

// Add an AssemblyDescription attribute
[assembly: AssemblyDescription("A sample description")]
namespace IsDef1CS
{
    public class DemoClass
    {
        static void Main(string[] args)
        {
            // Get the class type to access its metadata.
            Type clsType = typeof(DemoClass);
            // Get the assembly object.
            Assembly assy = clsType.Assembly;
            // Store the assembly's name.
            String assyName = assy.GetName().Name;
            // See if the Assembly Description is defined.
            bool isdef = Attribute.IsDefined(assy,
                typeof(AssemblyDescriptionAttribute));
            if (isdef)
            {
                // Affirm that the attribute is defined.
                Console.WriteLine("The AssemblyDescription attribute " +
                    "is defined for assembly {0}.", assyName);
                // Get the description attribute itself.
                AssemblyDescriptionAttribute adAttr =
                    (AssemblyDescriptionAttribute)Attribute.GetCustomAttribute(
                    assy, typeof(AssemblyDescriptionAttribute));
                // Display the description.
                if (adAttr != null)
                    Console.WriteLine("The description is \"{0}\".",
                        adAttr.Description);
                else
                    Console.WriteLine("The description could not " +
                        "be retrieved.");
            }
            else
                Console.WriteLine("The AssemblyDescription attribute is not " +
                    "defined for assembly {0}.", assyName);
        }
    }
}

/*
 * Output:
 * The AssemblyDescription attribute is defined for assembly IsDef1CS.
 * The description is "A sample description".
 */

open System
open System.Reflection

// Add an AssemblyDescription attribute
[<assembly: AssemblyDescription "A sample description">]
do ()

type DemoClass = class end

// Get the class type to access its metadata.
let clsType = typeof<DemoClass>

// Get the assembly object.
let assembly = clsType.Assembly;

// Store the assembly's name.
let assemblyName = assembly.GetName().Name

// See if the Assembly Description is defined.
let isdef = 
    Attribute.IsDefined(assembly, typeof<AssemblyDescriptionAttribute>)

if isdef then
    // Affirm that the attribute is defined.
    printfn $"The AssemblyDescription attribute is defined for assembly {assemblyName}."
    
    // Get the description attribute itself.
    let adAttr =
        Attribute.GetCustomAttribute(assembly, typeof<AssemblyDescriptionAttribute>)
        :?> AssemblyDescriptionAttribute

    // Display the description.
    if adAttr <> null then
        printfn $"The description is \"{adAttr.Description}\"."
    else
        printfn $"The description could not be retrieved."
else
    printfn $"The AssemblyDescription attribute is not defined for assembly {assemblyName}."

// Output:
//  The AssemblyDescription attribute is defined for assembly IsDef1FS.
//  The description is "A sample description".

Imports System.Reflection

' Add an AssemblyDescription attribute.
<Assembly: AssemblyDescription("A sample description")> 

Module DemoModule
    Sub Main()
        ' Get the assembly for this module.
        Dim assy As System.Reflection.Assembly = GetType(DemoModule).Assembly
        ' Store the assembly name.
        Dim assyName As String = assy.GetName().Name
        ' See if the AssemblyDescription attribute is defined.
        If Attribute.IsDefined(assy, GetType(AssemblyDescriptionAttribute)) _
            Then
            ' Affirm that the attribute is defined. Assume the filename of
            ' this code example is "IsDef1VB".
            Console.WriteLine("The AssemblyDescription attribute is " & _
                "defined for assembly {0}.", assyName)
            ' Get the description attribute itself.
            Dim attr As Attribute = Attribute.GetCustomAttribute( _
                assy, GetType(AssemblyDescriptionAttribute))
            ' Display the description.
            If Not attr Is Nothing And _
                TypeOf attr Is AssemblyDescriptionAttribute Then
                Dim adAttr As AssemblyDescriptionAttribute = _
                    CType(attr, AssemblyDescriptionAttribute)
                Console.WriteLine("The description is " & _
                    Chr(34) & "{0}" & Chr(34) & ".", adAttr.Description)
            Else
                Console.WriteLine("The description could not be retrieved.")
            End If
        Else
            Console.WriteLine("The AssemblyDescription attribute is not " & _
                              "defined for assembly {0}.", assyName)
        End If
    End Sub
End Module

' Output:
' The AssemblyDescription attribute is defined for assembly IsDef1VB.
' The description is "A sample description".

注解

注释

适用于

IsDefined(ParameterInfo, Type)

Source:: Attribute.CoreCLR.cs

Source:: Attribute.CoreCLR.cs

Source:: Attribute.CoreCLR.cs

Source:: Attribute.CoreCLR.cs

Source:: Attribute.CoreCLR.cs

确定是否将任何自定义属性应用于方法参数。参数指定要搜索的方法参数和自定义属性的类型。

public:
 static bool IsDefined(System::Reflection::ParameterInfo ^ element, Type ^ attributeType);

public static bool IsDefined(System.Reflection.ParameterInfo element, Type attributeType);

static member IsDefined : System.Reflection.ParameterInfo * Type -> bool

Public Shared Function IsDefined (element As ParameterInfo, attributeType As Type) As Boolean

参数

element: ParameterInfo

一个派生自 ParameterInfo 描述类成员的参数的类的对象。

attributeType: Type

要搜索的自定义属性的类型或基类型。

Boolean

如果应用于类型的自定义属性，则为 ;否则为 < a1/>。

例外

ArgumentNullException

element 或 attributeType 为 null.

ArgumentException

attributeType 不是派生自 Attribute.

示例

下面的代码示例演示了采用参数作为参数的IsDefined ParameterInfo用法。

using System;
using System.Reflection;

namespace IsDef5CS
{
    public class TestClass
    {
        // Assign a ParamArray attribute to the parameter using the keyword.
        public void Method1(params String[] args)
        {}
    }

    public class DemoClass
    {
        static void Main(string[] args)
        {
            // Get the class type to access its metadata.
            Type clsType = typeof(TestClass);
            // Get the MethodInfo object for Method1.
            MethodInfo mInfo = clsType.GetMethod("Method1");
            // Get the ParameterInfo array for the method parameters.
            ParameterInfo[] pInfo = mInfo.GetParameters();
            if (pInfo != null)
            {
                // See if the ParamArray attribute is defined.
                bool isDef = Attribute.IsDefined(pInfo[0],
                                                 typeof(ParamArrayAttribute));
                // Display the result.
                Console.WriteLine("The ParamArray attribute {0} defined for " +
                                  "parameter {1} of method {2}.",
                                  isDef ? "is" : "is not",
                                  pInfo[0].Name,
                                  mInfo.Name);
            }
            else
                Console.WriteLine("The parameters information could " +
                            "not be retrieved for method {0}.", mInfo.Name);
        }
    }
}

/*
 * Output:
 * The ParamArray attribute is defined for parameter args of method Method1.
 */

open System;

type TestClass() =
    // Assign a ParamArray attribute to the parameter.
    member _.Method1([<ParamArray>] args: string[]) = ()

// Get the class type to access its metadata.
let clsType = typeof<TestClass>

// Get the MethodInfo object for Method1.
let mInfo = clsType.GetMethod "Method1"

// Get the ParameterInfo array for the method parameters.
let pInfo = mInfo.GetParameters()

if pInfo <> null then
    // See if the ParamArray attribute is defined.
    let isDef = Attribute.IsDefined(pInfo[0], typeof<ParamArrayAttribute>)

    // Display the result.
    printfn $"""The ParamArray attribute {if isDef then "is" else "is not"} defined for parameter {pInfo[0].Name} of method {mInfo.Name}."""
else
    printfn $"The parameters information could not be retrieved for method {mInfo.Name}."

// Output:
//  The ParamArray attribute is defined for parameter args of method Method1.

Imports System.Reflection

Module DemoModule
    Public Class TestClass
        ' Assign a ParamArray attribute to the parameter using the keyword.
        Public Sub Method1(ByVal ParamArray args As String())
        End Sub
    End Class

    Sub Main()
        ' Get the class type to access its metadata.
        Dim clsType As Type = GetType(TestClass)
        ' Get the MethodInfo object for Method1.
        Dim mInfo As MethodInfo = clsType.GetMethod("Method1")
        ' Get the ParameterInfo array for the method parameters.
        Dim pInfo() As ParameterInfo = mInfo.GetParameters()
        If Not pInfo(0) Is Nothing Then
            ' See if the ParamArray attribute is defined.
            Dim isDef As Boolean = Attribute.IsDefined(pInfo(0), _
                                   GetType(ParamArrayAttribute))
            Dim strDef As String
            If isDef = True Then
                strDef = "is"
            Else
                strDef = "is not"
            End If
            ' Display the result.
            Console.WriteLine("The ParamArray attribute {0} defined " & _
                              "for parameter {1} of method {2}.", _
                              strDef, pInfo(0).Name, mInfo.Name)
        Else
            Console.WriteLine("Could not retrieve parameter information " & _
                              "for method {0}.", mInfo.Name)
        End If
    End Sub
End Module

' Output:
' The ParamArray attribute is defined for parameter args of method Method1.

注解

搜索自定义属性的 element 上级。

适用于

反馈

此页面是否有帮助？

通过

Attribute.IsDefined 方法

定义

重载

IsDefined(ParameterInfo, Type, Boolean)

参数

返回

例外

示例

适用于

IsDefined(Module, Type, Boolean)

参数

返回

例外

示例

注解

适用于

IsDefined(MemberInfo, Type, Boolean)

参数

返回

例外

示例

注解

适用于

IsDefined(Assembly, Type, Boolean)

参数

返回

例外

示例

注解

适用于

IsDefined(MemberInfo, Type)

参数

返回

例外

示例

注解

适用于

IsDefined(Module, Type)

参数

返回

例外

示例

注解

适用于

IsDefined(Assembly, Type)

参数

返回

例外

示例

注解

适用于

IsDefined(ParameterInfo, Type)

参数

返回

例外

示例

注解

适用于

反馈