c# – Protobuf-net：无法创建抽象类的实例

发布时间：2020-12-15 21:08:48 所属栏目：百科来源：网络整理

导读：根据这里找到的代码： protobuf and Listobject – how to serialize / deserialize?我创建了一个通用的“ProtoDictionary”,其值类型为ProtoObject. 这是我的ProtoDictionary代码： public class ProtoDictionaryTKey : DictionaryTKey,ProtoObject{ public

根据这里找到的代码： protobuf and List<object> – how to serialize / deserialize?我创建了一个通用的“ProtoDictionary”,其值类型为ProtoObject.

这是我的ProtoDictionary代码：

public class ProtoDictionary<TKey> : Dictionary<TKey,ProtoObject>
{
    public void Add(TKey key,string value)
    {
        base.Add(key,new ProtoObject<<string>(value));
    }

    public void Add(TKey key,List<string> value)
    {
        base.Add(key,new ProtoObject<List<string>>(value));
    }

    public void Add(TKey key,List<UrlStatus> value)
    {
        base.Add(key,new ProtoObject<List<UrlStatus>>(value));
    }

    public void Add(TKey key,Dictionary<string,string> value)
    {
        base.Add(key,new ProtoObject<Dictionary<string,string>>(value));
    }

    public void Add(TKey key,int> value)
    {
        base.Add(key,int>>(value));
    }

    public void Add(TKey key,List<TrafficEntry> value)
    {
        base.Add(key,new ProtoObject<List<TrafficEntry>>(value));
    }

    public ProtoDictionary()
    {
        // Do nothing
    }

    // NOTE: For whatever reason,this class will not correctly deserialize without this method,even though
    // the base class,Dictionary,has the SerializableAttribute. It's protected so only the framework can access it.
    protected ProtoDictionary(SerializationInfo info,StreamingContext context) : base(info,context) 
    {

    }
}

对于ProtoObject：

[ProtoContract]
[ProtoInclude(1,typeof(ProtoObject<string>))]
[ProtoInclude(2,typeof(ProtoObject<int>))]
[ProtoInclude(3,typeof(ProtoObject<List<string>>))]
[ProtoInclude(4,typeof(ProtoObject<Dictionary<string,string>>))]
[ProtoInclude(5,typeof(ProtoObject<List<TrafficEntry>>))]
[ProtoInclude(6,int>>))]
[ProtoInclude(7,typeof(ProtoObject<bool>))]
[ProtoInclude(8,typeof(ProtoObject<double>))]
[ProtoInclude(9,typeof(ProtoObject<decimal>))]
[ProtoInclude(10,typeof(ProtoObject<float>))]
[ProtoInclude(11,typeof(ProtoObject<long>))]
[ProtoInclude(12,typeof(ProtoObject<SerializableException>))]
[ProtoInclude(13,typeof(ProtoObject<List<UrlStatus>>))]
[Serializable]
public abstract class ProtoObject
{
    public static ProtoObject<T> Create<T>(T value)
    {
        return new ProtoObject<T>(value);
    }

    public object Value
    {
        get { return ValueImpl; }
        set { ValueImpl = value; }
    }

    protected abstract object ValueImpl { get; set; }

    protected ProtoObject()
    {

    }
}

[ProtoContract]
[Serializable]
public sealed class ProtoObject<T> : ProtoObject
{
    public ProtoObject()
    {

    }

    public ProtoObject(T value)
    { 
        Value = value; 
    }

    [ProtoMember(1)]
    public new T Value { get; set; }

    protected override object ValueImpl
    {
        get { return Value; }
        set { Value = (T)value; }
    }

    public override string ToString()
    {
        return Value.ToString();
    }
}

问题是,当我尝试使用以下代码从SQL反序列化ProtoDictionary时：

public T Deserialize<T>(IDataReader reader,string columnName)
{
    MemoryStream stream = new MemoryStream();
    byte[] buffer = new byte[256];          
    long startIndex = 0;
    long bytesRead = reader.GetBytes(reader.GetOrdinal(columnName),startIndex,buffer,buffer.Length);

    while(bytesRead == buffer.Length)
    {
        stream.Write(buffer,(int)bytesRead);                
        startIndex += bytesRead;
        bytesRead = reader.GetBytes(reader.GetOrdinal(columnName),buffer.Length);
    }

    stream.Write(buffer,(int)bytesRead);
    stream.Seek(0,SeekOrigin.Begin);

    return (T)Utilities.Deserialize<T>(stream);
}

我收到错误“InvalidOperationException：无法创建抽象类的实例.”

我的StackTrace如下：

   at ctorWrapper()
   at ProtoBuf.ObjectFactory`1.Create() in c:protobuf-net_fixedtrunkprotobuf-netObjectFactory.cs:line 82
   at ProtoBuf.Serializer`1.Deserialize[TCreation](T& instance,SerializationContext context) in c:protobuf-net_fixedtrunkprotobuf-netSerializerT.cs:line 568
   at ProtoBuf.Property.PropertyMessageString`4.DeserializeImpl(TSource source,SerializationContext context) in c:protobuf-net_fixedtrunkprotobuf-netPropertyPropertyMessageString.cs:line 53
   at ProtoBuf.Property.PropertyPairString`3.DeserializeImpl(TSource source,SerializationContext context) in c:protobuf-net_fixedtrunkprotobuf-netPropertyPropertyPairString.cs:line 53
   at ProtoBuf.Property.PropertyList`3.DeserializeImpl(TSource source,SerializationContext context,Boolean canSetValue) in c:protobuf-net_fixedtrunkprotobuf-netPropertyPropertyList.cs:line 64
   at ProtoBuf.Property.PropertyList`3.Deserialize(TSource source,SerializationContext context) in c:protobuf-net_fixedtrunkprotobuf-netPropertyPropertyList.cs:line 52
   at ProtoBuf.Serializer`1.Deserialize[TCreation](T& instance,SerializationContext context) in c:protobuf-net_fixedtrunkprotobuf-netSerializerT.cs:line 568
   at ProtoBuf.Serializer`1.DeserializeChecked[TCreation](T& instance,SerializationContext source) in c:protobuf-net_fixedtrunkprotobuf-netSerializerT.cs:line 400
   at ProtoBuf.SerializerSimpleProxy`1.Deserialize(TValue& value,SerializationContext source) in c:protobuf-net_fixedtrunkprotobuf-netSerializerProxy.cs:line 100
   at ProtoBuf.Serializer.Deserialize[T](SerializationContext source) in c:protobuf-net_fixedtrunkprotobuf-netSerializer.cs:line 302
   at ProtoBuf.Serializer.Deserialize[T](Stream source) in c:protobuf-net_fixedtrunkprotobuf-netSerializer.cs:line 289
   at Demand.TestFramework.Core.Utilities.Deserialize[T](MemoryStream stream) in C:QAtrunkTestFrameworkCoreUtilities.cs:line 312
   at Demand.TestFramework.Core.Reports.CrawlerReport.Deserialize[T](IDataReader reader,String columnName) in C:QAtrunkTestFrameworkCoreReportsCrawlerReport.cs:line 145
   at Demand.TestFramework.Core.Reports.CrawlerReport.FormatSuite(Int32 parentSuiteId,Guid runId) in C:QAtrunkTestFrameworkCoreReportsCrawlerReport.cs:line 70
   at Demand.TestFramework.Core.Reports.CrawlerReport.Format(Guid runId) in C:QAtrunkTestFrameworkCoreReportsCrawlerReport.cs:line 150
   at ServiceLauncher.Form1.btnStart_Click(Object sender,EventArgs e) in C:QAtrunkTestFrameworkServiceLauncherForm1.cs:line 24
   at System.Windows.Forms.Control.OnClick(EventArgs e)
   at System.Windows.Forms.Button.OnClick(EventArgs e)
   at System.Windows.Forms.Button.OnMouseUp(MouseEventArgs mevent)
   at System.Windows.Forms.Control.WmMouseUp(Message& m,MouseButtons button,Int32 clicks)
   at System.Windows.Forms.Control.WndProc(Message& m)
   at System.Windows.Forms.ButtonBase.WndProc(Message& m)
   at System.Windows.Forms.Button.WndProc(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
   at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd,Int32 msg,IntPtr wparam,IntPtr lparam)
   at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG& msg)
   at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(IntPtr dwComponentID,Int32 reason,Int32 pvLoopData)
   at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason,ApplicationContext context)
   at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason,ApplicationContext context)
   at System.Windows.Forms.Application.Run(Form mainForm)
   at ServiceLauncher.Program.Main() in C:QAtrunkTestFrameworkServiceLauncherProgram.cs:line 16
   at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly,String[] args)
   at System.AppDomain.ExecuteAssembly(String assemblyFile,Evidence assemblySecurity,String[] args)
   at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
   at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext,ContextCallback callback,Object state,Boolean ignoreSyncCtx)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext,Object state)
   at System.Threading.ThreadHelper.ThreadStart()

我不确定我做错了什么.任何帮助将不胜感激.

谢谢,
担

解决方法

这可能仅仅是“v1”中的限制.我已经 added this作为“v2”的测试了,它通过了(我必须发明UrlStatus和TrafficEntry才能让它编译)：

public enum UrlStatus { A,B }
    public enum TrafficEntry { A }
    [ProtoContract]
    public class SerializableException { }

    [Test]
    public void TestBasicRoundTrip()
    {
        var item = new ProtoDictionary<string>();
        item.Add("abc","def");
        item.Add("ghi",new List<UrlStatus> {UrlStatus.A,UrlStatus.B});

        var clone = Serializer.DeepClone(item);
        Assert.AreEqual(2,clone.Keys.Count);
        object o = clone["abc"];
        Assert.AreEqual("def",clone["abc"].Value);
        var list = (IList<UrlStatus>)clone["ghi"].Value;
        Assert.AreEqual(2,list.Count);
        Assert.AreEqual(UrlStatus.A,list[0]);
        Assert.AreEqual(UrlStatus.B,list[1]);
    }

使用“v1”,或许根本就不要把它抽象化？ (解决方法,不修复)

也;不需要SerializationInfo ctor; protobuf-net不使用它(虽然你可以通过提供这个方法并调用Merge在BinaryFormatter中实现protobuf-net)

（编辑：李大同）

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