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Informazioni sul tipo di visualizzazione

La classe System.Type è centrale per il riflesso. Common Language Runtime crea il Type per un tipo caricato quando Reflection lo richiede. È possibile usare i metodi, i campi, le proprietà e le classi annidate di un oggetto Type per scoprire tutti gli elementi relativi a tale tipo.

Utilizzare Assembly.GetType o Assembly.GetTypes per ottenere Type oggetti da assembly non caricati, passando il nome del tipo o dei tipi desiderati. Usare Type.GetType per ottenere gli oggetti Type da un assembly già caricato. Usare Module.GetType e Module.GetTypes per ottenere oggetti del modulo Type.

Nota

Per esaminare e manipolare tipi e metodi generici, ti preghiamo di consultare le informazioni aggiuntive fornite in Reflection e Tipi generici e Procedura: Esaminare e creare istanze di tipi generici con reflection.

Nell'esempio seguente viene illustrata la sintassi necessaria per ottenere l'oggetto e il modulo Assembly per un assembly.

// Gets the mscorlib assembly in which the object is defined.
Assembly a = typeof(object).Module.Assembly;

' Gets the mscorlib assembly in which the object is defined.
Dim a As Assembly = GetType(Object).Module.Assembly

Il seguente esempio illustra come ottenere gli oggetti Type da un assembly caricato.

// Loads an assembly using its file name.
Assembly a = Assembly.LoadFrom("MyExe.exe");
// Gets the type names from the assembly.
Type[] types2 = a.GetTypes();
foreach (Type t in types2)
{
    Console.WriteLine(t.FullName);
}

' Loads an assembly using its file name.
Dim a As Assembly = Assembly.LoadFrom("MyExe.exe")
' Gets the type names from the assembly.
Dim types2() As Type = a.GetTypes()
For Each t As Type In types2
    Console.WriteLine(t.FullName)
Next t

Dopo aver ottenuto un Type, è possibile individuare informazioni sui membri di tale tipo in molti modi. Ad esempio, è possibile trovare informazioni su tutti i membri del tipo chiamando il metodo Type.GetMembers, che ottiene una matrice di oggetti MemberInfo che descrivono ognuno dei membri del tipo corrente.

È anche possibile utilizzare metodi nella classe Type per recuperare informazioni su uno o più costruttori, metodi, eventi, campi o proprietà specificati in base al nome. Ad esempio, Type.GetConstructor incapsula un costruttore specifico della classe corrente.

Se si dispone di un Type, è possibile utilizzare la proprietà Type.Module per ottenere un oggetto che incapsula il modulo contenente tale tipo. Utilizzare la proprietà Module.Assembly per individuare un oggetto che incapsula l'assembly contenente il modulo. È possibile ottenere direttamente l'assembly che incapsula il tipo usando la proprietà Type.Assembly.

System.Type e ConstructorInfo

Nell'esempio seguente viene illustrato come elencare i costruttori per una classe, in questo caso la classe String.

// This program lists all the public constructors
// of the System.String class.
using System;
using System.Reflection;

class ListMembers
{
    public static void Main()
    {
        Type t = typeof(System.String);
        Console.WriteLine($"Listing all the public constructors of the {t} type");
        // Constructors.
        ConstructorInfo[] ci = t.GetConstructors(BindingFlags.Public | BindingFlags.Instance);
        Console.WriteLine("//Constructors");
        PrintMembers(ci);
    }

    public static void PrintMembers(MemberInfo[] ms)
    {
        foreach (MemberInfo m in ms)
        {
            Console.WriteLine($"{"     "}{m}");
        }
        Console.WriteLine();
    }
}

' This program lists all the public constructors
' of the System.String class.

Imports System.Reflection

Class ListMembers
    Public Shared Sub Main()
        Dim t As Type = GetType(String)
        Console.WriteLine("Listing all the public constructors of the {0} type", t)
        ' Constructors.
        Dim ci As ConstructorInfo() = t.GetConstructors((BindingFlags.Public Or BindingFlags.Instance))
        Console.WriteLine("//Constructors")
        PrintMembers(ci)
    End Sub
    Public Shared Sub PrintMembers(ms() As MemberInfo)
        Dim m As MemberInfo
        For Each m In ms
            Console.WriteLine("{0}{1}", "     ", m)
        Next m
        Console.WriteLine()
    End Sub
End Class

MemberInfo, MethodInfo, FieldInfo e PropertyInfo

Ottenere informazioni sui metodi, le proprietà, gli eventi e i campi del tipo usando MemberInfo, MethodInfo, FieldInfoo oggetti PropertyInfo.

L'esempio seguente usa MemberInfo per elencare il numero di membri nella classe System.IO.File e usa la proprietà IsPublic per determinare la visibilità della classe.

using System;
using System.IO;
using System.Reflection;

class MyMemberInfo
{
    public static void Main()
    {
        Console.WriteLine ("\nReflection.MemberInfo");
        // Gets the Type and MemberInfo.
        Type myType = Type.GetType("System.IO.File");
        MemberInfo[] myMemberInfoArray = myType.GetMembers();
        // Gets and displays the DeclaringType method.
        Console.WriteLine($"\nThere are {myMemberInfoArray.Length} members in {myType.FullName}.");
        Console.WriteLine($"{myType.FullName}.");
        if (myType.IsPublic)
        {
            Console.WriteLine($"{myType.FullName} is public.");
        }
    }
}

Imports System.IO
Imports System.Reflection

Class MyMemberInfo
    Public Shared Sub Main()
        Console.WriteLine("\nReflection.MemberInfo")
        ' Gets the Type and MemberInfo.
        Dim myType As Type = Type.GetType("System.IO.File")
        Dim myMemberInfoArray() As MemberInfo = myType.GetMembers()
        ' Gets and displays the DeclaringType method.
        Console.WriteLine("\nThere are {0} members in {1}.",
            myMemberInfoArray.Length, myType.FullName)
        Console.WriteLine("{0}.", myType.FullName)
        If myType.IsPublic
            Console.WriteLine("{0} is public.", myType.FullName)
        End If
    End Sub
End Class

Nell'esempio seguente viene esaminato il tipo del membro specificato. Esegue un'operazione di reflection su un membro della classe MemberInfo e ne elenca il tipo.

// This code displays information about the GetValue method of FieldInfo.
using System;
using System.Reflection;

class MyMethodInfo
{
    public static int Main()
    {
        Console.WriteLine("Reflection.MethodInfo");
        // Gets and displays the Type.
        Type myType = Type.GetType("System.Reflection.FieldInfo");
        // Specifies the member for which you want type information.
        MethodInfo myMethodInfo = myType.GetMethod("GetValue");
        Console.WriteLine(myType.FullName + "." + myMethodInfo.Name);
        // Gets and displays the MemberType property.
        MemberTypes myMemberTypes = myMethodInfo.MemberType;
        if (MemberTypes.Constructor == myMemberTypes)
        {
            Console.WriteLine("MemberType is of type All");
        }
        else if (MemberTypes.Custom == myMemberTypes)
        {
            Console.WriteLine("MemberType is of type Custom");
        }
        else if (MemberTypes.Event == myMemberTypes)
        {
            Console.WriteLine("MemberType is of type Event");
        }
        else if (MemberTypes.Field == myMemberTypes)
        {
            Console.WriteLine("MemberType is of type Field");
        }
        else if (MemberTypes.Method == myMemberTypes)
        {
            Console.WriteLine("MemberType is of type Method");
        }
        else if (MemberTypes.Property == myMemberTypes)
        {
            Console.WriteLine("MemberType is of type Property");
        }
        else if (MemberTypes.TypeInfo == myMemberTypes)
        {
            Console.WriteLine("MemberType is of type TypeInfo");
        }
        return 0;
    }
}

' This code displays information about the GetValue method of FieldInfo.
Imports System.Reflection
Class MyMethodInfo
    Public Shared Sub Main()
        Console.WriteLine("Reflection.MethodInfo")
        ' Gets and displays the Type.
        Dim myType As Type = Type.GetType("System.Reflection.FieldInfo")
        ' Specifies the member for which you want type information.
        Dim myMethodInfo As MethodInfo = myType.GetMethod("GetValue")
        Console.WriteLine((myType.FullName & "." & myMethodInfo.Name))
        ' Gets and displays the MemberType property.
        Dim myMemberTypes As MemberTypes = myMethodInfo.MemberType
        If MemberTypes.Constructor = myMemberTypes Then
            Console.WriteLine("MemberType is of type All")
        ElseIf MemberTypes.Custom = myMemberTypes Then
            Console.WriteLine("MemberType is of type Custom")
        ElseIf MemberTypes.Event = myMemberTypes Then
            Console.WriteLine("MemberType is of type Event")
        ElseIf MemberTypes.Field = myMemberTypes Then
            Console.WriteLine("MemberType is of type Field")
        ElseIf MemberTypes.Method = myMemberTypes Then
            Console.WriteLine("MemberType is of type Method")
        ElseIf MemberTypes.Property = myMemberTypes Then
            Console.WriteLine("MemberType is of type Property")
        ElseIf MemberTypes.TypeInfo = myMemberTypes Then
            Console.WriteLine("MemberType is of type TypeInfo")
        End If
        Return
    End Sub
End Class

Nell'esempio seguente vengono utilizzate tutte le classi Reflection *Info insieme a BindingFlags per elencare tutti i membri (costruttori, campi, proprietà, eventi e metodi) della classe specificata, dividendo i membri in categorie statiche e di istanza.

// This program lists all the members of the
// System.IO.BufferedStream class.
using System;
using System.IO;
using System.Reflection;

class ListMembers
{
    public static void Main()
    {
        // Specifies the class.
        Type t = typeof(System.IO.BufferedStream);
        Console.WriteLine($"Listing all the members (public and non public) of the {t} type");

        // Lists static fields first.
        FieldInfo[] fi = t.GetFields(BindingFlags.Static |
            BindingFlags.NonPublic | BindingFlags.Public);
        Console.WriteLine("// Static Fields");
        PrintMembers(fi);

        // Static properties.
        PropertyInfo[] pi = t.GetProperties(BindingFlags.Static |
            BindingFlags.NonPublic | BindingFlags.Public);
        Console.WriteLine("// Static Properties");
        PrintMembers(pi);

        // Static events.
        EventInfo[] ei = t.GetEvents(BindingFlags.Static |
            BindingFlags.NonPublic | BindingFlags.Public);
        Console.WriteLine("// Static Events");
        PrintMembers(ei);

        // Static methods.
        MethodInfo[] mi = t.GetMethods (BindingFlags.Static |
            BindingFlags.NonPublic | BindingFlags.Public);
        Console.WriteLine("// Static Methods");
        PrintMembers(mi);

        // Constructors.
        ConstructorInfo[] ci = t.GetConstructors(BindingFlags.Instance |
            BindingFlags.NonPublic | BindingFlags.Public);
        Console.WriteLine("// Constructors");
        PrintMembers(ci);

        // Instance fields.
        fi = t.GetFields(BindingFlags.Instance | BindingFlags.NonPublic |
            BindingFlags.Public);
        Console.WriteLine("// Instance Fields");
        PrintMembers(fi);

        // Instance properties.
        pi = t.GetProperties(BindingFlags.Instance | BindingFlags.NonPublic |
            BindingFlags.Public);
        Console.WriteLine ("// Instance Properties");
        PrintMembers(pi);

        // Instance events.
        ei = t.GetEvents(BindingFlags.Instance | BindingFlags.NonPublic |
            BindingFlags.Public);
        Console.WriteLine("// Instance Events");
        PrintMembers(ei);

        // Instance methods.
        mi = t.GetMethods(BindingFlags.Instance | BindingFlags.NonPublic
            | BindingFlags.Public);
        Console.WriteLine("// Instance Methods");
        PrintMembers(mi);

        Console.WriteLine("\r\nPress ENTER to exit.");
        Console.Read();
    }

    public static void PrintMembers (MemberInfo [] ms)
    {
        foreach (MemberInfo m in ms)
        {
            Console.WriteLine ("{0}{1}", "     ", m);
        }
        Console.WriteLine();
    }
}

' This program lists all the members of the
' System.IO.BufferedStream class.
Imports System.IO
Imports System.Reflection

Class ListMembers
    Public Shared Sub Main()
        ' Specifies the class.
        Dim t As Type = GetType(System.IO.BufferedStream)
        Console.WriteLine("Listing all the members (public and non public) of the {0} type", t)
        ' Lists static fields first.
        Dim fi As FieldInfo() = t.GetFields((BindingFlags.Static Or BindingFlags.NonPublic Or BindingFlags.Public))
        Console.WriteLine("// Static Fields")
        PrintMembers(fi)
        ' Static properties.
        Dim pi As PropertyInfo() = t.GetProperties((BindingFlags.Static Or BindingFlags.NonPublic Or BindingFlags.Public))
        Console.WriteLine("// Static Properties")
        PrintMembers(pi)
        ' Static events.
        Dim ei As EventInfo() = t.GetEvents((BindingFlags.Static Or BindingFlags.NonPublic Or BindingFlags.Public))
        Console.WriteLine("// Static Events")
        PrintMembers(ei)
        ' Static methods.
        Dim mi As MethodInfo() = t.GetMethods((BindingFlags.Static Or BindingFlags.NonPublic Or BindingFlags.Public))
        Console.WriteLine("// Static Methods")
        PrintMembers(mi)
        ' Constructors.
        Dim ci As ConstructorInfo() = t.GetConstructors((BindingFlags.Instance Or BindingFlags.NonPublic Or BindingFlags.Public))
        Console.WriteLine("// Constructors")
        PrintMembers(ci)
        ' Instance fields.
        fi = t.GetFields((BindingFlags.Instance Or BindingFlags.NonPublic Or BindingFlags.Public))
        Console.WriteLine("// Instance Fields")
        PrintMembers(fi)
        ' Instance properties.
        pi = t.GetProperties((BindingFlags.Instance Or BindingFlags.NonPublic Or BindingFlags.Public))
        Console.WriteLine("// Instance Properties")
        PrintMembers(pi)
        ' Instance events.
        ei = t.GetEvents((BindingFlags.Instance Or BindingFlags.NonPublic Or BindingFlags.Public))
        Console.WriteLine("// Instance Events")
        PrintMembers(ei)
        ' Instance methods.
        mi = t.GetMethods((BindingFlags.Instance Or BindingFlags.NonPublic Or BindingFlags.Public))
        Console.WriteLine("// Instance Methods")
        PrintMembers(mi)
        Console.WriteLine(ControlChars.CrLf & "Press ENTER to exit.")
        Console.Read()
    End Sub

    Public Shared Sub PrintMembers(ms() As MemberInfo)
        Dim m As MemberInfo
        For Each m In ms
            Console.WriteLine("{0}{1}", "     ", m)
        Next m
        Console.WriteLine()
    End Sub
End Class
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