c# - 为什么我的非关闭流仍然关闭？

Question

我有一个非关闭流类，它包装在一个带有二进制读取器的 using block 中，但由于某种原因，当该 block 结束时，我的非关闭流仍然关闭。

流定义为:

internal class NonClosingStream : Stream, IDisposable
{
    private Stream baseStream;

    public NonClosingStream(Stream baseStream)
    {
        this.baseStream = baseStream;
    }

    public override bool CanRead{ get { return baseStream.CanRead; } }
    public override bool CanSeek{ get { return baseStream.CanSeek; } }
    public override bool CanWrite { get { return baseStream.CanWrite; } }

    public override void Flush()
    {
        baseStream.Flush();
    }

    public override long Length { get { return baseStream.Length; } }

    public override long Position
    {
        get { return baseStream.Position; }
        set { baseStream.Position = value; }
    }

    public override int Read(byte[] buffer, int offset, int count)
    {
        return baseStream.Read(buffer, offset, count);   
    }

    public override long Seek(long offset, SeekOrigin origin)
    {
        return baseStream.Seek(offset, origin);
    }

    public override void SetLength(long value)
    {
        baseStream.SetLength(value);
    }

    public override void Write(byte[] buffer, int offset, int count)
    {
        baseStream.Write(buffer, offset, count);
    }

    public override void Close()
    {
        // Disconnects from base stream, but does not close it
        this.baseStream = null;
    }

    void IDisposable.Dispose()
    {
        // Disconnects from base stream, but does not close it
        this.baseStream = null;
    }
}

读取 block 看起来像这样:

public T Deserialize<T>(Stream stream)
{
    using (NonClosingStream nonClosingStream = new NonClosingStream(stream))
    using (BinaryReader reader = new BinaryReader(nonClosingStream, Encoding.ASCII, true))
    {
        // Read the type name, then convert it to an actual type
        String typeName = reader.ReadString();
        Type graphType = AvailableTypes.GetType(typeName);

        // If a deserializer for this type already exists, use it.
        if (deserializerFunctions.ContainsKey(graphType))
        {
            return (T)deserializerFunctions[graphType](reader);
        }

        // Otherwise, create one and use it
        T graph = (T)FormatterServices.GetUninitializedObject(graphType);

        typeof(ServiceSerializer).GetMethod("DeserializeObject",
                BindingFlags.NonPublic | BindingFlags.Static)

            .MakeGenericMethod(graphType)
            .Invoke(this, new Object[] { reader, graph });

        return graph;
    }
}

我做错了什么？

更新

所以我写了这个小家伙:

static void Main()
{
    MemoryStream stream = new MemoryStream();
    using (NonClosingStream nonCloser = new NonClosingStream(stream))
    using (BinaryWriter writer = new BinaryWriter(nonCloser))
    using (BinaryReader reader= new BinaryReader(nonCloser))
    {
        writer.Write("Lorem ipsum");

        stream.Seek(0, SeekOrigin.Begin);
        String data = reader.ReadString();

        Console.WriteLine(data);
    }

    stream.Seek(0, SeekOrigin.Begin);

    using (NonClosingStream nonCloser = new NonClosingStream(stream))
    using (BinaryWriter writer = new BinaryWriter(nonCloser))
    using (BinaryReader reader = new BinaryReader(nonCloser))
    {
        writer.Write("Lorem ipsum");

        stream.Seek(0, SeekOrigin.Begin);
        String data = reader.ReadString();

        Console.WriteLine(data);
    }

    Console.ReadLine();
}

它似乎工作正常，流像预期的那样保持打开状态。所以我想共识是正确的。我以某种方式关闭了其他地方的流。当我弄清楚我会发布结果时。谢谢大家。

更新

Gaaaahhh，我想通了问题。因此，代码的工作方式是，在序列化/反序列化一个对象的同时，它会从表达式树中构建一个自定义的序列化程序，然后对其进行编译，以便将来的序列化更加流畅。这意味着我的代码中充斥着这样的东西:

Action<BinaryReader, Object> assignmentAction = delegate(BinaryReader bReader, Object oGraph)
{
    bReader.ReadByte();      // Read the next action
    bReader.ReadString();    // Read the field name
    bReader.ReadByte();      // Read the field type

    // Call the assignment lambda
    assignmentLambda(reader, deserializerFunctions[primitiveType], (T)oGraph);
};

你听懂了吗？不？我显然也没有。让我们添加一些上下文:

private static void DeserializeObject<T>(BinaryReader reader, T graph)
{
    ...

    Action<BinaryReader, Object> assignmentAction = delegate(BinaryReader bReader, Object oGraph)
    {
        bReader.ReadByte();      // Read the next action
        bReader.ReadString();    // Read the field name
        bReader.ReadByte();      // Read the field type

        // Call the assignment lambda
        assignmentLambda(reader, deserializerFunctions[primitiveType], (T)oGraph);
    };

    ...
}

lambda 正在从外部 block 关闭 reader，而不是使用缓存反序列化器运行时提供的 bReader。因此，当反序列化器运行时，它使用的是已经丢弃的二进制读取器对象，而不是提供给它的新对象。我想问题不是我要关闭流，而是我使用的是废弃的阅读器。至少这解释了为什么它会工作一次，然后第二次失败，因为它第二次依赖于缓存的反序列化器。糟糕!

谢谢大家。

Answer 1

由于您的流不会创建内部流，因此很可能外部代码会关闭您的内部流。您的代码很可能如下所示:

 NonClosingStream nonClosing;
 using(var stream = new FileStream(...))
 {
   nonClosing = new NonClosingStream(stream );
  ....
 } 
 // inner stream now closed and nonClosing will fail all operations.