StreamingContext.State プロパティとは何？わかりやすく解説 Weblio辞書

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.NET Framework クラスライブラリリファレンス

索引トップ用語の索引ランキング

StreamingContext.State プロパティ

送信データの送信元または送信先を取得します。

名前空間: System.Runtime.Serialization
アセンブリ: mscorlib (mscorlib.dll 内)
構文

Visual Basic (宣言)

Public ReadOnly Property
 State As StreamingContextStates

Visual Basic (使用法)

Dim instance As StreamingContext
Dim value As StreamingContextStates

value = instance.State

public StreamingContextStates State { get;
 }

C++

public:
property StreamingContextStates State {
    StreamingContextStates get ();
}

/** @property */
public StreamingContextStates get_State ()

JScript

public function get State
 () : StreamingContextStates

プロパティ値
シリアル化中の送信データの送信先。逆シリアル化中のデータの送信元。

解説

シリアル化中に、現在のプロパティで送信データの送信先を指定します。たとえば、AppDomain をまたがるリモート処理でデータをシリアル化した場合、StreamingContextStates は CrossProcess です。逆シリアル化中には、状態が逆シリアル化ストリームの転送元を示します。

使用例

Visual Basic

Imports System
Imports System.IO
Imports System.Collections
Imports System.Runtime.Serialization.Formatters.Binary
Imports System.Runtime.Serialization
Imports System.Runtime.InteropServices
Imports System.Security.Permissions

<Assembly: SecurityPermission( _
SecurityAction.RequestMinimum, Execution:=True)> 
' This class includes several Win32 interop definitions.
Friend Class Win32
    Public Shared ReadOnly
 InvalidHandleValue As New IntPtr(-1)
    Public Const FILE_MAP_WRITE As
 Int32 = 2
    Public Const PAGE_READWRITE As
 Int32 = &H4

    <DllImport("Kernel32")> _
    Public Shared Function
 CreateFileMapping(ByVal hFile As IntPtr,
 _
                                             ByVal pAttributes
 As IntPtr, _
                                             ByVal flProtect As
 Int32, _
                                             ByVal dwMaximumSizeHigh
 As Int32, _
                                             ByVal dwMaximumSizeLow
 As Int32, _
                                             ByVal pName As
 String) As IntPtr
    End Function

    <DllImport("Kernel32")> _
    Public Shared Function
 OpenFileMapping(ByVal dwDesiredAccess As
 Int32, _
                                           ByVal bInheritHandle
 As Boolean, _
                                           ByVal name As
 String) As IntPtr
    End Function

    <DllImport("Kernel32")> _
    Public Shared Function
 CloseHandle(ByVal handle As IntPtr) As
 Boolean
    End Function

    <DllImport("Kernel32")> _
    Public Shared Function
 MapViewOfFile(ByVal hFileMappingObject As
 IntPtr, _
                                         ByVal dwDesiredAccess
 As Int32, _
                                         ByVal dwFileOffsetHigh
 As Int32, _
                                         ByVal dwFileOffsetLow
 As Int32, _
                                         ByVal dwNumberOfBytesToMap
 As IntPtr) _
                                         As IntPtr
    End Function

    <DllImport("Kernel32")> _
    Public Shared Function
 UnmapViewOfFile(ByVal address As IntPtr)
 As Boolean
    End Function

    <DllImport("Kernel32")> _
    Public Shared Function
 DuplicateHandle(ByVal hSourceProcessHandle As
 IntPtr, _
                                           ByVal hSourceHandle
 As IntPtr, _
                                           ByVal hTargetProcessHandle
 As IntPtr, _
                                           ByRef lpTargetHandle
 As IntPtr, _
                                           ByVal dwDesiredAccess
 As Int32, _
                                           ByVal bInheritHandle
 As Boolean, _
                                           ByVal dwOptions As
 Int32) As Boolean
    End Function

    Public Const DUPLICATE_CLOSE_SOURCE As
 Int32 = &H1
    Public Const DUPLICATE_SAME_ACCESS As
 Int32 = &H2

    <DllImport("Kernel32")> Public
 Shared Function GetCurrentProcess() As
 IntPtr
    End Function
End Class


' This class wraps memory that can be simultaneously 
' shared by multiple AppDomains and Processes.
<Serializable()> Public NotInheritable
 Class SharedMemory
    Implements ISerializable
    Implements IDisposable

    ' The handle and string that identify 
    ' the Windows file-mapping object.
    Private m_hFileMap As IntPtr = IntPtr.Zero
    Private m_name As String

    ' The address of the memory-mapped file-mapping object.
    Private m_address As IntPtr
    <SecurityPermissionAttribute(SecurityAction.LinkDemand, _
    Flags:=SecurityPermissionFlag.UnmanagedCode)> _
    Public Function GetByte(ByVal
 offset As Int32) As Byte
        Dim b(0) As Byte
        Marshal.Copy(New IntPtr(m_address.ToInt64() + offset),
 b, 0, 1)
        Return b(0)
    End Function

    <SecurityPermissionAttribute(SecurityAction.LinkDemand, _
    Flags:=SecurityPermissionFlag.UnmanagedCode)> _
    Public Sub SetByte(ByVal
 offset As Int32, ByVal value As
 Byte)
        Dim b(0) As Byte
        b(0) = value
        Marshal.Copy(b, 0, New IntPtr(m_address.ToInt64() + offset),
 1)
    End Sub


    ' The constructors.
    Public Sub New(ByVal
 size As Int32)
        Me.New(size, Nothing)
    End Sub

    Public Sub New(ByVal
 size As Int32, ByVal name As
 String)
        m_hFileMap = Win32.CreateFileMapping(Win32.InvalidHandleValue, _
           IntPtr.Zero, Win32.PAGE_READWRITE, 0, size, name)
        If (m_hFileMap.Equals(IntPtr.Zero)) Then
 _
           Throw New Exception("Could
 not create memory-mapped file.")
        m_name = name
        m_address = Win32.MapViewOfFile(m_hFileMap, _
           Win32.FILE_MAP_WRITE, 0, 0, IntPtr.Zero)
    End Sub


    ' The cleanup methods.
    Public Sub Dispose() Implements
 IDisposable.Dispose
        GC.SuppressFinalize(Me)
        Dispose(True)
    End Sub

    Private Sub Dispose(ByVal
 disposing As Boolean)
        Win32.UnmapViewOfFile(m_address)
        Win32.CloseHandle(m_hFileMap)
        m_address = IntPtr.Zero
        m_hFileMap = IntPtr.Zero
    End Sub

    Protected Overrides Sub
 Finalize()
        Dispose(False)
    End Sub


    ' Private helper methods.
    Private Shared Function
 AllFlagsSet(ByVal flags As Int32, _
                                        ByVal flagsToTest As
 Int32) As Boolean
        Return (flags And flagsToTest) = flagsToTest
    End Function

    Private Shared Function
 AnyFlagsSet(ByVal flags As Int32, _
                                        ByVal flagsToTest As
 Int32) As Boolean
        Return (flags And flagsToTest) <>
 0
    End Function


    ' The security attribute demands that code that calls  
    ' this method have permission to perform serialization.
    <SecurityPermissionAttribute(SecurityAction.Demand, SerializationFormatter:=True)>
 _
    Sub GetObjectData(ByVal info As
 SerializationInfo, _
                      ByVal context As StreamingContext)
 _
                      Implements ISerializable.GetObjectData
        ' The context's State member indicates where the object will
 be deserialized.

        ' A SharedMemory object cannot be serialized 
        ' to any of the following destinations.
        Const InvalidDestinations As StreamingContextStates
 = _
           StreamingContextStates.CrossMachine Or _
           StreamingContextStates.File Or _
           StreamingContextStates.Other Or _
           StreamingContextStates.Persistence Or _
           StreamingContextStates.Remoting
        If AnyFlagsSet(CType(context.State, Int32), _
                       CType(InvalidDestinations, Int32)) Then
            Throw New SerializationException("The
 SharedMemory object " & _
               "cannot be serialized to any of the following streaming
 contexts: " _
               & InvalidDestinations)
        End If

        Const DeserializableByHandle As StreamingContextStates
 = _
                 StreamingContextStates.Clone Or _
                 StreamingContextStates.CrossAppDomain

        If AnyFlagsSet(CType(context.State, Int32), _
              CType(DeserializableByHandle, Int32)) Then
            info.AddValue("hFileMap", m_hFileMap)
        End If

        Const DeserializableByName As StreamingContextStates
 = _
                 StreamingContextStates.CrossProcess   ' The same computer.
        If AnyFlagsSet(CType(context.State, Int32), CType(DeserializableByName,
 _
                       Int32)) Then
            If m_name = Nothing Then
                Throw New SerializationException("The
 SharedMemory object " & _
                   "cannot be serialized CrossProcess because
 it was not constructed " & _
                   "with a String name.")
            End If
            info.AddValue("name", m_name)
        End If
    End Sub

    Private Sub New(ByVal
 info As SerializationInfo, ByVal context
 As StreamingContext)
        ' The context's State member indicates where the object was
 serialized from.

        Const InvalidSources As StreamingContextStates
 = _
                 StreamingContextStates.CrossMachine Or _
                 StreamingContextStates.File Or _
                 StreamingContextStates.Other Or _
                 StreamingContextStates.Persistence Or _
                 StreamingContextStates.Remoting

        If AnyFlagsSet(CType(context.State, Int32), CType(InvalidSources,
 Int32)) Then
            Throw New SerializationException("The
 SharedMemory object " & _
               "cannot be deserialized from any of the following
 stream contexts: " & _
               InvalidSources)
        End If

        Const SerializedByHandle As StreamingContextStates
 = _
                 StreamingContextStates.Clone Or _
                 StreamingContextStates.CrossAppDomain ' The same process.
        If AnyFlagsSet(CType(context.State, Int32), _
              CType(SerializedByHandle, Int32)) Then
            Try
                Win32.DuplicateHandle(Win32.GetCurrentProcess(), _
                   CType(info.GetValue("hFileMap",
 GetType(IntPtr)), IntPtr), _
                      Win32.GetCurrentProcess(), m_hFileMap, 0, False,
 _
                      Win32.DUPLICATE_SAME_ACCESS)
            Catch e As SerializationException
                Throw New SerializationException("A
 SharedMemory was not " & _
                   "serialized using any of the following streaming
 contexts: " & _
                   SerializedByHandle)
            End Try
        End If

        Const SerializedByName As StreamingContextStates
 = _
                 StreamingContextStates.CrossProcess   ' The same computer.
        If AnyFlagsSet(CType(context.State, Int32), _
                       CType(SerializedByName, Int32)) Then
            Try
                m_name = info.GetString("name")
            Catch e As SerializationException
                Throw New SerializationException("A
 SharedMemory object " & _
                   "was not serialized using any of the following
 streaming contexts: " & _
                   SerializedByName)
            End Try
            m_hFileMap = Win32.OpenFileMapping(Win32.FILE_MAP_WRITE, False,
 m_name)
        End If
        If Not m_hFileMap.Equals(IntPtr.Zero)
 Then
            m_address = Win32.MapViewOfFile(m_hFileMap, _
               Win32.FILE_MAP_WRITE, 0, 0, IntPtr.Zero)
        Else
            Throw New SerializationException("A
 SharedMemory object " & _
               "could not be deserialized.")
        End If
    End Sub
End Class

Class App
    <STAThread()> Shared Sub Main()
        Serialize()
        Console.WriteLine()
        Deserialize()
    End Sub

    Shared Sub Serialize()
        ' Create a hashtable of values that will eventually be serialized.
        Dim sm As New SharedMemory(1024,
 "MyMemory")
        Dim x As Int32
        For x = 0 To 99
            sm.SetByte(x, x)
        Next

        Dim b(9) As Byte
        For x = 0 To b.Length - 1
            b(x) = sm.GetByte(x)
        Next
        Console.WriteLine(BitConverter.ToString(b))

        ' To serialize the hashtable (and its key/value pairs), you
 must first 
        ' open a stream for writing. Use a file stream here.
        Dim fs As New FileStream("DataFile.dat",
 FileMode.Create)

        ' Construct a BinaryFormatter telling it where 
        ' the objects will be serialized to.
        Dim formatter As New
 BinaryFormatter(Nothing, _
           New StreamingContext(StreamingContextStates.CrossAppDomain))
        Try
            formatter.Serialize(fs, sm)
        Catch e As SerializationException
            Console.WriteLine("Failed to serialize. Reason: "
 + e.Message)
            Throw
        Finally
            fs.Close()
        End Try
    End Sub

    Shared Sub Deserialize()
        ' Declare the hashtable reference.
        Dim sm As SharedMemory = Nothing

        ' Open the file containing the data that you want to deserialize.
        Dim fs As New FileStream("DataFile.dat",
 FileMode.Open)
        Try
            Dim Formatter As New
 BinaryFormatter(Nothing, _
               New StreamingContext(StreamingContextStates.CrossAppDomain))

            ' Deserialize the SharedMemory object from the file and
 
            ' assign the reference to the local variable.
            sm = DirectCast(Formatter.Deserialize(fs), SharedMemory)
        Catch e As SerializationException
            Console.WriteLine("Failed to deserialize. Reason:
 " & e.Message)
        Finally
            fs.Close()
        End Try

        ' To prove that the SharedMemory object deserialized correctly,
 
        ' display some of its bytes to the console.
        Dim b(9) As Byte
        Dim x As Int32
        For x = 0 To b.Length - 1
            b(x) = sm.GetByte(x)
        Next
        Console.WriteLine(BitConverter.ToString(b))
    End Sub
End Class

// Note: You must compile this file using the C# /unsafe switch.
using System;
using System.IO;
using System.Collections;
using System.Runtime.Serialization.Formatters.Binary;
using System.Runtime.Serialization;
using System.Runtime.InteropServices;
using System.Security.Permissions;

[assembly: SecurityPermission(
SecurityAction.RequestMinimum, Execution = true)]
// This class includes several Win32 interop definitions.
internal class Win32
{
    public static readonly IntPtr InvalidHandleValue
 = new IntPtr(-1);
    public const UInt32 FILE_MAP_WRITE = 2;
    public const UInt32 PAGE_READWRITE = 0x04;

    [DllImport("Kernel32")]
    public static extern IntPtr CreateFileMapping(IntPtr
 hFile,
        IntPtr pAttributes, UInt32 flProtect,
        UInt32 dwMaximumSizeHigh, UInt32 dwMaximumSizeLow, String pName);

    [DllImport("Kernel32")]
    public static extern IntPtr OpenFileMapping(UInt32
 dwDesiredAccess,
        Boolean bInheritHandle, String name);

    [DllImport("Kernel32")]
    public static extern Boolean CloseHandle(IntPtr
 handle);

    [DllImport("Kernel32")]
    public static extern IntPtr MapViewOfFile(IntPtr
 hFileMappingObject,
        UInt32 dwDesiredAccess,
        UInt32 dwFileOffsetHigh, UInt32 dwFileOffsetLow,
        IntPtr dwNumberOfBytesToMap);

    [DllImport("Kernel32")]
    public static extern Boolean UnmapViewOfFile(IntPtr
 address);

    [DllImport("Kernel32")]
    public static extern Boolean DuplicateHandle(IntPtr
 hSourceProcessHandle,
        IntPtr hSourceHandle,
        IntPtr hTargetProcessHandle, ref IntPtr lpTargetHandle,
        UInt32 dwDesiredAccess, Boolean bInheritHandle, UInt32 dwOptions);
    public const UInt32 DUPLICATE_CLOSE_SOURCE
 = 0x00000001;
    public const UInt32 DUPLICATE_SAME_ACCESS
 = 0x00000002;

    [DllImport("Kernel32")]
    public static extern IntPtr GetCurrentProcess();
}


// This class wraps memory that can be simultaneously 
// shared by multiple AppDomains and Processes.
[Serializable]
public sealed class SharedMemory : ISerializable,
 IDisposable
{
    // The handle and string that identify 
    // the Windows file-mapping object.
    private IntPtr m_hFileMap = IntPtr.Zero;
    private String m_name;

    // The address of the memory-mapped file-mapping object.
    private IntPtr m_address;

    public unsafe Byte* Address
    {
        get { return (Byte*)m_address; }
    }

    // The constructors.
    public SharedMemory(Int32 size) : this(size,
 null) { }

    public SharedMemory(Int32 size, String name)
    {
        m_hFileMap = Win32.CreateFileMapping(Win32.InvalidHandleValue,
            IntPtr.Zero, Win32.PAGE_READWRITE,
            0, unchecked((UInt32)size), name);
        if (m_hFileMap == IntPtr.Zero)
            throw new Exception("Could not create memory-mapped
 file.");
        m_name = name;
        m_address = Win32.MapViewOfFile(m_hFileMap, Win32.FILE_MAP_WRITE,
            0, 0, IntPtr.Zero);
    }

    // The cleanup methods.
    public void Dispose()
    {
        GC.SuppressFinalize(this);
        Dispose(true);
    }

    private void Dispose(Boolean disposing)
    {
        Win32.UnmapViewOfFile(m_address);
        Win32.CloseHandle(m_hFileMap);
        m_address = IntPtr.Zero;
        m_hFileMap = IntPtr.Zero;
    }

    ~SharedMemory()
    {
        Dispose(false);
    }

    // Private helper methods.
    private static Boolean AllFlagsSet(Int32
 flags, Int32 flagsToTest)
    {
        return (flags & flagsToTest) == flagsToTest;
    }

    private static Boolean AnyFlagsSet(Int32
 flags, Int32 flagsToTest)
    {
        return (flags & flagsToTest) != 0;
    }


    // The security attribute demands that code that calls  
    // this method have permission to perform serialization.
    [SecurityPermissionAttribute(SecurityAction.Demand, SerializationFormatter =
 true)]
    void ISerializable.GetObjectData(SerializationInfo info, StreamingContext
 context)
    {
        // The context's State member indicates
        // where the object will be deserialized.

        // A SharedMemory object cannot be serialized 
        // to any of the following destinations.
        const StreamingContextStates InvalidDestinations =
                  StreamingContextStates.CrossMachine |
                  StreamingContextStates.File |
                  StreamingContextStates.Other |
                  StreamingContextStates.Persistence |
                  StreamingContextStates.Remoting;
        if (AnyFlagsSet((Int32)context.State, (Int32)InvalidDestinations))
            throw new SerializationException("The SharedMemory
 object " +
                "cannot be serialized to any of the following streaming contexts:
 " +
                InvalidDestinations);

        const StreamingContextStates DeserializableByHandle =
                  StreamingContextStates.Clone |
            // The same process.
                  StreamingContextStates.CrossAppDomain;
        if (AnyFlagsSet((Int32)context.State, (Int32)DeserializableByHandle))
            info.AddValue("hFileMap", m_hFileMap);

        const StreamingContextStates DeserializableByName =
            // The same computer.
                  StreamingContextStates.CrossProcess;
        if (AnyFlagsSet((Int32)context.State, (Int32)DeserializableByName))
        {
            if (m_name == null)
                throw new SerializationException("The SharedMemory
 object " +
                    "cannot be serialized CrossProcess because it was not constructed
 " +
                    "with a String name.");
            info.AddValue("name", m_name);
        }
    }


    // The security attribute demands that code that calls  
    // this method have permission to perform serialization.
    [SecurityPermissionAttribute(SecurityAction.Demand, SerializationFormatter =
 true)]
    private SharedMemory(SerializationInfo info, StreamingContext
 context)
    {
        // The context's State member indicates 
        // where the object was serialized from.

        const StreamingContextStates InvalidSources =
                  StreamingContextStates.CrossMachine |
                  StreamingContextStates.File |
                  StreamingContextStates.Other |
                  StreamingContextStates.Persistence |
                  StreamingContextStates.Remoting;
        if (AnyFlagsSet((Int32)context.State, (Int32)InvalidSources))
            throw new SerializationException("The SharedMemory
 object " +
                "cannot be deserialized from any of the following stream contexts:
 " +
                InvalidSources);

        const StreamingContextStates SerializedByHandle =
                  StreamingContextStates.Clone |
            // The same process.
                  StreamingContextStates.CrossAppDomain;
        if (AnyFlagsSet((Int32)context.State, (Int32)SerializedByHandle))
        {
            try
            {
                Win32.DuplicateHandle(Win32.GetCurrentProcess(),
                    (IntPtr)info.GetValue("hFileMap", typeof(IntPtr)),
                    Win32.GetCurrentProcess(), ref m_hFileMap, 0, false
,
                    Win32.DUPLICATE_SAME_ACCESS);
            }
            catch (SerializationException)
            {
                throw new SerializationException("A SharedMemory
 was not serialized " +
                    "using any of the following streaming
 contexts: " +
                    SerializedByHandle);
            }
        }

        const StreamingContextStates SerializedByName =
            // The same computer.
                  StreamingContextStates.CrossProcess;
        if (AnyFlagsSet((Int32)context.State, (Int32)SerializedByName))
        {
            try
            {
                m_name = info.GetString("name");
            }
            catch (SerializationException)
            {
                throw new SerializationException("A SharedMemory
 object was not " +
                    "serialized using any of the following
 streaming contexts: " +
                    SerializedByName);
            }
            m_hFileMap = Win32.OpenFileMapping(Win32.FILE_MAP_WRITE, false,
 m_name);
        }
        if (m_hFileMap != IntPtr.Zero)
        {
            m_address = Win32.MapViewOfFile(m_hFileMap, Win32.FILE_MAP_WRITE,
                0, 0, IntPtr.Zero);
        }
        else
        {
            throw new SerializationException("A SharedMemory
 object could not " +
                "be deserialized.");
        }
    }
}


class App
{
    [STAThread]
    static void Main(string[]
 args)
    {
        Serialize();
        Console.WriteLine();
        Deserialize();
    }

    unsafe static void Serialize()
    {
        // Create a hashtable of values that will eventually be serialized.
        SharedMemory sm = new SharedMemory(1024, "JeffMemory");
        for (Int32 x = 0; x < 100; x++)
            *(sm.Address + x) = (Byte)x;

        Byte[] b = new Byte[10];
        for (Int32 x = 0; x < b.Length; x++) b[x] = *(sm.Address
 + x);
        Console.WriteLine(BitConverter.ToString(b));

        // To serialize the SharedMemory object, 
        // you must first open a stream for writing. 
        // Use a file stream here.
        FileStream fs = new FileStream("DataFile.dat",
 FileMode.Create);

        // Construct a BinaryFormatter and tell it where 
        // the objects will be serialized to.
        BinaryFormatter formatter = new BinaryFormatter(null
,
            new StreamingContext(StreamingContextStates.CrossAppDomain));
        try
        {
            formatter.Serialize(fs, sm);
        }
        catch (SerializationException e)
        {
            Console.WriteLine("Failed to serialize. Reason: " + e.Message);
            throw;
        }
        finally
        {
            fs.Close();
        }
    }


    unsafe static void Deserialize()
    {
        // Declare a SharedMemory reference.
        SharedMemory sm = null;

        // Open the file containing the data that you want to deserialize.
        FileStream fs = new FileStream("DataFile.dat",
 FileMode.Open);
        try
        {
            BinaryFormatter formatter = new BinaryFormatter(null
,
                new StreamingContext(StreamingContextStates.CrossAppDomain));

            // Deserialize the SharedMemory object from the file and
 
            // assign the reference to the local variable.
            sm = (SharedMemory)formatter.Deserialize(fs);
        }
        catch (SerializationException e)
        {
            Console.WriteLine("Failed to deserialize. Reason: " + e.Message);
            throw;
        }
        finally
        {
            fs.Close();
        }

        // To prove that the SharedMemory object deserialized correctly,
 
        // display some of its bytes to the console.
        Byte[] b = new Byte[10];
        for (Int32 x = 0; x < b.Length; x++) b[x] = *(sm.Address
 + x);
        Console.WriteLine(BitConverter.ToString(b));
    }
}

プラットフォーム

バージョン情報

.NET Framework
サポート対象 : 2.0、1.1、1.0

参照

関連項目
StreamingContext 構造体
StreamingContext メンバ
System.Runtime.Serialization 名前空間

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