ObjRef 类
存储生成代理以与远程对象通信所需的所有相关信息。
**命名空间:**System.Runtime.Remoting
**程序集:**mscorlib（在 mscorlib.dll 中）
语法
声明
<SerializableAttribute> _
<ComVisibleAttribute(True)> _
Public Class ObjRef
Implements IObjectReference, ISerializable
用法
Dim instance As ObjRef
[SerializableAttribute]
[ComVisibleAttribute(true)]
public class ObjRef : IObjectReference, ISerializable
[SerializableAttribute]
[ComVisibleAttribute(true)]
public ref class ObjRef : IObjectReference, ISerializable
/** @attribute SerializableAttribute() */
/** @attribute ComVisibleAttribute(true) */
public class ObjRef implements IObjectReference, ISerializable
SerializableAttribute
ComVisibleAttribute(true)
public class ObjRef implements IObjectReference, ISerializable
备注
ObjRef 是扩展 MarshalByRefObject (MBR) 的对象的可序列化表示。ObjRef 用于跨 AppDomain 边界传输对象引用。为对象创建 ObjRef 称为封送。既可以显式创建也可以隐式创建 ObjRef（封送 MarshalByRefObject）；显式创建方法是向远程处理结构注册 MBR 对象（请参见 RemotingConfiguration 和 RemotingServices.Marshal），而隐式创建方法是在调用远程对象时以参数形式传递 MBR 对象。远程处理使用 ObjRef 对象来存储和传输有关被远程处理的 MarshalByRefObject 的所有相关信息。
ObjRef 包含的信息描述了被封送处理的对象的 Type 和类、它的准确位置以及有关如何到达对象所在的远程处理分支的通信相关信息。
实现 MarshalByRefObject 的类被封送后，表示它的 ObjRef 通过信道传输到另一个应用程序域（可能位于另一进程或计算机中）。当 ObjRef 在目标应用程序域中反序列化时（请参见 XML 和 SOAP 序列化），将对其进行分析以为远程 MBR 对象创建透明代理。此操作称为拆收处理 (Unmarshaling)。
透明代理是提供实际对象驻留在客户端空间中的假象的对象。它实现这一点的方法是：使用远程处理基础结构将对其进行的调用转发给真实对象。透明代理本身由类型 RealProxy 的托管运行时类的实例收容。RealProxy 实现从透明代理转发操作所需的部分功能。
可以在不考虑 AppDomain 中任何远程处理分支的情况下使用代理对象。应用程序不需要区分代理引用和对象引用。但是，处理激活、生存期管理和事务等问题的服务提供程序需要进行这种区分。
此类在类级别生成链接要求和继承要求。如果直接调用方或继承类没有基础结构权限，则会引发 SecurityException。有关安全要求的详细信息，请参见 链接要求 和 继承要求。
示例
下面的代码示例说明如何使用自定义 ObjRef。若要查看对自定义的 ObjRef 进行测试的激活代码的示例，请参见 RegisterWellKnownServiceType 方法的示例。
' a custom ObjRef class that outputs its status
<PermissionSet(SecurityAction.Demand, Name:="FullTrust")> _
Public Class MyObjRef
Inherits ObjRef
' only instantiate using marshaling or deserialization
Private Sub New()
End Sub
Public Sub New(ByVal o As MarshalByRefObject, ByVal t As Type)
MyBase.New(o, t)
Console.WriteLine("Created MyObjRef.")
ORDump()
End Sub
Public Sub New(ByVal i As SerializationInfo, ByVal c As StreamingContext)
MyBase.New(i, c)
Console.WriteLine("Deserialized MyObjRef.")
End Sub
Public Overrides Sub GetObjectData(ByVal s As SerializationInfo, ByVal c As StreamingContext)
' After calling the base method, change the type from ObjRef to MyObjRef
MyBase.GetObjectData(s, c)
s.SetType([GetType]())
Console.WriteLine("Serialized MyObjRef.")
End Sub
Public Overrides Function GetRealObject(ByVal context As StreamingContext) As [Object]
If IsFromThisAppDomain() Or IsFromThisProcess() Then
Console.WriteLine("Returning actual object referenced by MyObjRef.")
Return MyBase.GetRealObject(context)
Else
Console.WriteLine("Returning proxy to remote object.")
Return RemotingServices.Unmarshal(Me)
End If
End Function
Public Sub ORDump()
Console.WriteLine(" --- Reporting MyObjRef Info --- ")
Console.WriteLine("Reference to {0}.", TypeInfo.TypeName)
Console.WriteLine("URI is {0}.", URI)
Console.WriteLine(ControlChars.Cr + "Writing EnvoyInfo: ")
If Not (EnvoyInfo Is Nothing) Then
Dim EISinks As IMessageSink = EnvoyInfo.EnvoySinks
Dim count As Integer = 0
While Not (EISinks Is Nothing)
Console.WriteLine(ControlChars.Tab + "Interated through sink #{0}", (count = count + 1))
EISinks = EISinks.NextSink
End While
Else
Console.WriteLine(ControlChars.Tab + " {no sinks}")
End If
Console.WriteLine(ControlChars.Cr + "Writing ChannelInfo: ")
Dim i As Integer
For i = 0 To ChannelInfo.ChannelData.Length - 1
Console.WriteLine(ControlChars.Tab + "Channel: {0}", ChannelInfo.ChannelData(i))
Next i
Console.WriteLine(" ----------------------------- ")
End Sub
End Class
' a class that uses MyObjRef
<PermissionSet(SecurityAction.Demand, Name:="FullTrust")> _
Public Class LocalObject
Inherits MarshalByRefObject
' overriding CreateObjRef will allow us to return a custom ObjRef
Public Overrides Function CreateObjRef(ByVal t As Type) As ObjRef
Return New MyObjRef(Me, t)
End Function
End Class
// a custom ObjRef class that outputs its status
[PermissionSet(SecurityAction.Demand, Name="FullTrust")]
public class MyObjRef : ObjRef {
// only instantiate using marshaling or deserialization
private MyObjRef() { }
public MyObjRef(MarshalByRefObject o, Type t) : base(o, t) {
Console.WriteLine("Created MyObjRef.");
ORDump();
}
public MyObjRef(SerializationInfo i, StreamingContext c) : base(i, c) {
Console.WriteLine("Deserialized MyObjRef.");
}
public override void GetObjectData(SerializationInfo s, StreamingContext c) {
// After calling the base method, change the type from ObjRef to MyObjRef
base.GetObjectData(s, c);
s.SetType(GetType());
Console.WriteLine("Serialized MyObjRef.");
}
public override Object GetRealObject(StreamingContext context) {
if ( IsFromThisAppDomain() || IsFromThisProcess() ) {
Console.WriteLine("Returning actual object referenced by MyObjRef.");
return base.GetRealObject(context);
}
else {
Console.WriteLine("Returning proxy to remote object.");
return RemotingServices.Unmarshal(this);
}
}
public void ORDump() {
Console.WriteLine(" --- Reporting MyObjRef Info --- ");
Console.WriteLine("Reference to {0}.", TypeInfo.TypeName);
Console.WriteLine("URI is {0}.", URI);
Console.WriteLine("\nWriting EnvoyInfo: ");
if ( EnvoyInfo != null) {
IMessageSink EISinks = EnvoyInfo.EnvoySinks;
while (EISinks != null) {
Console.WriteLine("\tSink: " + EISinks.ToString());
EISinks = EISinks.NextSink;
}
}
else
Console.WriteLine("\t {no sinks}");
Console.WriteLine("\nWriting ChannelInfo: ");
for (int i = 0; i < ChannelInfo.ChannelData.Length; i++)
Console.WriteLine ("\tChannel: {0}", ChannelInfo.ChannelData[i]);
Console.WriteLine(" ----------------------------- ");
}
}
// a class that uses MyObjRef
[PermissionSet(SecurityAction.Demand, Name="FullTrust")]
public class LocalObject : MarshalByRefObject {
// overriding CreateObjRef will allow us to return a custom ObjRef
public override ObjRef CreateObjRef(Type t) {
return new MyObjRef(this, t);
}
}
// a custom ObjRef class that outputs its status
[System::Security::Permissions::SecurityPermissionAttribute(
System::Security::Permissions::SecurityAction::Demand,
Flags=System::Security::Permissions::SecurityPermissionFlag::SerializationFormatter)]
[System::Security::Permissions::SecurityPermissionAttribute
(System::Security::Permissions::SecurityAction::Demand,
Flags=System::Security::Permissions::SecurityPermissionFlag::Infrastructure)]
[System::Security::Permissions::SecurityPermissionAttribute
(System::Security::Permissions::SecurityAction::InheritanceDemand,
Flags=System::Security::Permissions::SecurityPermissionFlag::Infrastructure)]
public ref class MyObjRef: public ObjRef
{
private:
// only instantiate using marshaling or deserialization
MyObjRef(){}
public:
MyObjRef( MarshalByRefObject^ o, Type^ t )
: ObjRef( o, t )
{
Console::WriteLine( "Created MyObjRef." );
ORDump();
}
MyObjRef( SerializationInfo^ i, StreamingContext c )
: ObjRef( i, c )
{
Console::WriteLine( "Deserialized MyObjRef." );
}
virtual void GetObjectData( SerializationInfo^ s, StreamingContext c ) override
{
// After calling the base method, change the type from ObjRef to MyObjRef
ObjRef::GetObjectData( s, c );
s->SetType( GetType() );
Console::WriteLine( "Serialized MyObjRef." );
}
virtual Object^ GetRealObject( StreamingContext context ) override
{
if ( IsFromThisAppDomain() || IsFromThisProcess() )
{
Console::WriteLine( "Returning actual Object^ referenced by MyObjRef." );
return ObjRef::GetRealObject( context );
}
else
{
Console::WriteLine( "Returning proxy to remote Object^." );
return RemotingServices::Unmarshal( this );
}
}
void ORDump()
{
Console::WriteLine( " --- Reporting MyObjRef Info --- " );
Console::WriteLine( "Reference to {0}.", TypeInfo->TypeName );
Console::WriteLine( "URI is {0}.", URI );
Console::WriteLine( "\nWriting EnvoyInfo: " );
if ( EnvoyInfo != nullptr )
{
IMessageSink^ EISinks = EnvoyInfo->EnvoySinks;
while ( EISinks != nullptr )
{
Console::WriteLine( "\tSink: {0}", EISinks );
EISinks = EISinks->NextSink;
}
}
else
Console::WriteLine( "\t {no sinks}" );
Console::WriteLine( "\nWriting ChannelInfo: " );
for ( int i = 0; i < ChannelInfo->ChannelData->Length; i++ )
Console::WriteLine( "\tChannel: {0}", ChannelInfo->ChannelData[ i ] );
Console::WriteLine( " ----------------------------- " );
}
};
// a class that uses MyObjRef
public ref class LocalObject: public MarshalByRefObject
{
public:
// overriding CreateObjRef will allow us to return a custom ObjRef
[System::Security::Permissions::SecurityPermissionAttribute
(System::Security::Permissions::SecurityAction::LinkDemand,
Flags=System::Security::Permissions::SecurityPermissionFlag::Infrastructure)]
virtual ObjRef^ CreateObjRef( Type^ t ) override
{
return gcnew MyObjRef( this,t );
}
};
.NET Framework 安全性
- SecurityPermission 用于操作基础结构代码。要求值：SecurityAction.LinkDemand；权限值：SecurityPermissionFlag.Infrastructure
- SecurityPermission 用于操作基础结构代码。要求值：SecurityAction.InheritanceDemand；权限值：SecurityPermissionFlag.Infrastructure
继承层次结构
System.Object
System.Runtime.Remoting.ObjRef
线程安全
此类型的任何公共静态（Visual Basic 中的 Shared）成员都是线程安全的，但不保证所有实例成员都是线程安全的。
平台
Windows 98、Windows 2000 SP4、Windows Millennium Edition、Windows Server 2003、Windows XP Media Center Edition、Windows XP Professional x64 Edition、Windows XP SP2、Windows XP Starter Edition
.NET Framework 并不是对每个平台的所有版本都提供支持。有关受支持版本的列表，请参见系统要求。
版本信息
.NET Framework
受以下版本支持：2.0、1.1、1.0
请参见
参考
ObjRef 成员
System.Runtime.Remoting 命名空间
ISerializable
RemotingServices.Marshal
RemotingServices.Unmarshal
RealProxy