在 MVC Controller 中，不依靠定制路由，随心所欲地拦截请求和处理请求，想怎么输入输出都

Asp.net 中的 MVC，其主要面向 “text” 类型的 Content-Type 来处理 HTTP 请求，除了文件传输之外，就连 json、xml 也都是文本类型。

在路由上，我实在找不到办法，于是就转入 Controller 本身，看看它能否直接处理二进制数据，特别关注 Controller 是怎么把响应数据发回给客户端的，ContentResult，JsonResult，FileStreamResult?等等，都是用来发回响应的，我于是翻看了下?ContentResult 的 .NET 源代码，然后恍然大悟。

public class ContentResult : ActionResult
{
    public override void ExecuteResult(ControllerContext context)
    {
        if( context == null )
            throw new ArgumentNullException("context");

        HttpResponseBase response = context.HttpContext.Response;
        if( !string.IsNullOrEmpty( this.ContentType ) )
            response.ContentType = this.ContentType;

        if( this.ContentEncoding != null )
            response.ContentEncoding = this.ContentEncoding;

        if( this.Content != null )
            response.Write(this.Content);
    }

    public string Content { get; set; }

    public Encoding ContentEncoding { get; set; }

    public string ContentType { get; set; }
}

  在 ContentResult?中，它的 ExecuteResult() 不就是调用 HttpContext.Response.Write() 把数据写入 response，发回客户端的吗。只是，ExecuteResult() 不是由我们直接调用的，而是在我们的?Controller 的 Action() 处理结束返回该?ContentResult 对象后，由 MVC 接着调用的。

  为啥非要让 MVC 调用?Response.Write()，我直接调用不也可以吗？我调用完之后，返回一个 EmptyResult，让它啥也不干，不就好了吗？

  再翻看?EmptyResult 的 .NET 源码发现，它确实啥也不干，空空如也。其内部只实现了一个单例模型。

  再来看看 Request 请求，我测试后发现，服务器端确实能接收到二进制流，如下所示：

public class TestController : Controller
{
    [HttpPost]
    public ActionResult Index()
    {
        MemoryStream inStream = new MemStream( Math.Max( Request.TotalBytes, 64 ) );
        Request.InputStream.CopyTo( inStream );

        // 对 inStream 做处理，将响应数据放在 rspData 中，然后：

        Response.OutputStream.Write( rspData, 0, rspData.Length );

        return EmptyResult.Instance;
    }
}

  就这么简单，你想怎样处理 HTTP 的流进流出，都随你的意。

  你也可以从?ActionResult 派生一个自己的类，例如 MyResult，在其?ExecuteResult() 接口实现中，参照?ContentResult 的代码，把响应数据?rspData 发回。而在上面的?TestController.Index() 返回你的 new?MyResult(?rspData ).

?

  接下来，我们来看看，各种编程语言的互操作问题，大家都赞同以 Json，Xml 来序列化数据，然后在各个平台，各种语言，各个操作系统之间交互，以我看，这并不一定简单易用。来看看我提供的一个序列化工具，简单易用，内存占用少，稍作修改就可以跨平台。

  这个工具，提供 3 个类和一个接口，就是抄的 C# 的 MemoryStream，BinaryWriter，BinaryReader 的源码来编写。C# 的实现上，有诸多的小问题，例如，它无法处理 null 字符串，而这个工具能序列化 null 字符串。此外，C# 的这些类，搞了一堆没啥用的 Dispose()，有时候莫名其妙地，其内部的 Stream 就被 Dispose() 了。而这个工具，不用理会这些，它只隐含继承基类的 Dispose()。谁创建的 Stream，就由谁负责?Dispose()，否则就乱套了。

internal class BinWriter
    {
        Stream   stream;
        Encoding encoding;
        byte[]   _buffer;

        internal BinWriter( Stream stream, Encoding encoding )
        {
            this.stream = stream;
            this.encoding = encoding;
            _buffer = new byte[8];
        }

        internal void Write( bool value )
        {
            stream.WriteByte( value ? ((byte)1) : ((byte) 0) );
        }

        internal void Write( byte value )
        {
            stream.WriteByte( value );
        }

        internal void Write( short value )
        {
            _buffer[0] = (byte) value;
            _buffer[1] = (byte) (value >> 8);
            stream.Write( _buffer, 0, 2 );
        }

        internal void Write( int value )
        {
            _buffer[0] = (byte) value;
            _buffer[1] = (byte) (value >> 8);
            _buffer[2] = (byte) (value >> 0x10);
            _buffer[3] = (byte) (value >> 0x18);
            stream.Write( _buffer, 0, 4 );
        }

        internal void Write( long value )
        {
            _buffer[0] = (byte) value;
            _buffer[1] = (byte) (value >> 8);
            _buffer[2] = (byte) (value >> 0x10);
            _buffer[3] = (byte) (value >> 0x18);
            _buffer[4] = (byte) (value >> 0x20);
            _buffer[5] = (byte) (value >> 40);
            _buffer[6] = (byte) (value >> 0x30);
            _buffer[7] = (byte) (value >> 0x38);
            stream.Write( _buffer, 0, 8 );
        }

        internal void Write( string value )
        {
            if( value == null )
                Write7BitEncodedInt( stream, Int32.MinValue );
            else if( value.Length == 0 )
                Write7BitEncodedInt( stream, 0 );
            else
            {
                byte[] bstr = encoding.GetBytes( value );
                Write7BitEncodedInt( stream, bstr.Length );
                stream.Write( bstr, 0, bstr.Length );
            }
        }

        internal void Write( ushort value )
        {
            _buffer[0] = (byte) value;
            _buffer[1] = (byte) (value >> 8);
            stream.Write( _buffer, 0, 2 );
        }

        internal void Write( uint value )
        {
            _buffer[0] = (byte) value;
            _buffer[1] = (byte) (value >> 8);
            _buffer[2] = (byte) (value >> 0x10);
            _buffer[3] = (byte) (value >> 0x18);
            stream.Write( _buffer, 0, 4 );
        }

        internal void Write( ulong value )
        {
            _buffer[0] = (byte) value;
            _buffer[1] = (byte) (value >> 8);
            _buffer[2] = (byte) (value >> 0x10);
            _buffer[3] = (byte) (value >> 0x18);
            _buffer[4] = (byte) (value >> 0x20);
            _buffer[5] = (byte) (value >> 40);
            _buffer[6] = (byte) (value >> 0x30);
            _buffer[7] = (byte) (value >> 0x38);
            stream.Write( _buffer, 0, 8 );
        }

        internal void Write( DateTime value )
        {
            Write( value.ToBinary() );
        }

        internal void Write( byte[] buffer, int index, int count )
        {
            stream.Write( buffer, index, count );
        }

        internal static void Write7BitEncodedInt( Stream strm, int value )
        {
            uint num = (uint)value;
            while( num >= 0x80 )
            {
                strm.WriteByte( (byte) (num | 0x80) );
                num = num >> 7;
            }
            strm.WriteByte( (byte)num );
        }
    }

    internal class BinReader
    {
        Stream   stream;
        Encoding encoding;
        byte[]   _buffer;

        internal BinReader( Stream stream, Encoding encoding )
        {
            this.stream = stream;
            this.encoding = encoding;
            _buffer = new byte[128];
        }

        internal int Read( byte[] buffer, int index, int count )
        {
            return stream.Read( buffer, index, count );
        }

        internal bool ReadBool()
        {
            return stream.ReadByte() > 0;
        }

        internal byte ReadByte()
        {
            return (byte)stream.ReadByte();
        }

        internal short ReadInt16()
        {
            stream.Read( _buffer, 0, 2 );
            return (short)(_buffer[0] | (_buffer[1] << 8));
        }

        internal int ReadInt32()
        {
            stream.Read( _buffer, 0, 4 );
            return (((_buffer[0] | (_buffer[1] << 8)) | (_buffer[2] << 0x10)) | (_buffer[3] << 0x18));
        }

        internal long ReadInt64()
        {
            stream.Read( _buffer, 0, 8 );
            uint num = (uint) (((_buffer[0] | (_buffer[1] << 8)) | (_buffer[2] << 0x10)) | (_buffer[3] << 0x18));
            ulong num2 = (ulong) (((_buffer[4] | (_buffer[5] << 8)) | (_buffer[6] << 0x10)) | (_buffer[7] << 0x18));
            return (long) ((num2 << 0x20) | num);
        }

        internal string ReadString()
        {
            int capacity = Read7BitEncodedInt( stream );
            if( capacity == Int32.MinValue )
                return null;
            else if( capacity == 0 )
                return "";

            MemStream memStr = stream as MemStream;
            if( memStr == null )
            {
                if( _buffer.Length < capacity )
                    _buffer = new byte[capacity];

                stream.Read( _buffer, 0, capacity );
                return encoding.GetString( _buffer, 0, capacity );
            }
            else
            {
                string str = encoding.GetString( memStr.GetBuffer(), (int)memStr.Position, capacity );
                memStr.Seek( capacity, SeekOrigin.Current );
                return str;
            }
        }

        internal ushort ReadUInt16()
        {
            stream.Read( _buffer, 0, 2 );
            return (ushort) (_buffer[0] | (_buffer[1] << 8));
        }

        internal uint ReadUInt32()
        {
            stream.Read( _buffer, 0, 4 );
            return (uint) (((_buffer[0] | (_buffer[1] << 8)) | (_buffer[2] << 0x10)) | (_buffer[3] << 0x18));
        }

        internal ulong ReadUInt64()
        {
            stream.Read( _buffer, 0, 8 );
            uint num = (uint) (((_buffer[0] | (_buffer[1] << 8)) | (_buffer[2] << 0x10)) | (_buffer[3] << 0x18));
            ulong num2 = (ulong) (((_buffer[4] | (_buffer[5] << 8)) | (_buffer[6] << 0x10)) | (_buffer[7] << 0x18));
            return ((num2 << 0x20) | num);
        }

        internal DateTime ReadDate()
        {
            return DateTime.FromBinary( ReadInt64() );
        }

        internal static int Read7BitEncodedInt( Stream strm )
        {
            byte num3;
            int num = 0, num2 = 0;
            do
            {
                if( num2 == 0x23 )
                    throw new FormatException( "Stream Format Error" );
                num3 = (byte)strm.ReadByte();
                num |= (num3 & 0x7f) << num2;
                num2 += 7;
            }
            while( (num3 & 0x80) != 0 );
            return num;
        }
    }

    internal class MemStream : Stream
    {
        byte[] _buffer;
        int _capacity, _length;
        int _origin, _position;

        internal MemStream() : this(0)
        {
        }

        internal MemStream( int capacity )
        {
            if( capacity > 0 )
                _buffer = new byte[capacity];
            _capacity = capacity;
        }

        internal MemStream( byte[] buffer )
        {
            SetBuffer( buffer );
        }

        internal MemStream( byte[] buffer, int index, int count )
        {
            SetBuffer( buffer, index, count );
        }

        internal void SetBuffer( byte[] buffer )
        {
            _buffer = buffer;
            _length = _capacity = buffer.Length;
            _origin = _position = 0;
        }

        internal void SetBuffer( byte[] buffer, int index, int count )
        {
            _buffer = buffer;
            _length = _capacity = index + count;
            _origin = _position = index;
        }

        internal bool EnsureCapacity( int value )
        {
            if( value <= _capacity )
                return false;

            int num = value;
            if( num < 0x100 )
                num = 0x100;

            if( num < _capacity * 2 )
                num = _capacity * 2;
            if( _capacity * 2 > 0x7fffffc7 )
                num = (value > 0x7fffffc7) ? value : 0x7fffffc7;
            Capacity = num;
            return true;
        }

        public override void Flush()
        {
        }

        public virtual byte[] GetBuffer()
        {
            return _buffer;
        }

        internal byte[] ToBytesArray()
        {
            int    memLen = (int)this.Length;
            byte[] aryBytes = new byte[memLen];
            if( memLen > 0 )
                Array.Copy( _buffer, _origin, aryBytes, 0, memLen );
            return aryBytes;
        }

        /// <summary>
        /// 从当前流读取字节序列，并将此流中的位置提升读取的字节数。
        /// </summary>
        /// <param name="offset">buffer 中的从零开始的字节偏移量，从此处开始存储从当前流中读取的数据。</param>
        /// <param name="count">要从当前流中最多读取的字节数</param>
        /// <returns>读入缓冲区中的总字节数。如果当前可用的字节数没有请求的字节数那么多，则总字节数可能小于请求的字节数；如果已到达流的末尾，则为零 (0)。</returns>
        public override int Read( byte[] buffer, int offset, int count )
        {
            int byteCount = _length - _position;
            if( byteCount > count )
                byteCount = count;
            if( byteCount <= 0 )
                return 0;
            if( byteCount <= 8 )
            {
                int num2 = byteCount;
                while( --num2 >= 0 )
                    buffer[offset + num2] = _buffer[_position + num2];
            }
            else
                Array.Copy( _buffer, _position, buffer, offset, byteCount );
            _position += byteCount;
            return byteCount;
        }

        public override int ReadByte()
        {
            if( _position >= _length )
                return -1;
            return _buffer[_position++];
        }

        public override long Seek( long offset, SeekOrigin loc )
        {
            switch( loc )
            {
                case SeekOrigin.Begin:
                {
                    int num = _origin + (int)offset;
                    if( offset < 0L || num < _origin )
                        throw new IOException( "IO.IO_SeekBeforeBegin" );
                    _position = num;
                    break;
                }
                case SeekOrigin.Current:
                {
                    int num2 = _position + (int)offset;
                    if( (_position + offset) < _origin || num2 < _origin )
                        throw new IOException( "IO.IO_SeekBeforeBegin" );
                    _position = num2;
                    break;
                }
                case SeekOrigin.End:
                {
                    int num3 = _length + (int)offset;
                    if( (_length + offset) < _origin || num3 < _origin )
                        throw new IOException( "IO.IO_SeekBeforeBegin" );
                    _position = num3;
                    break;
                }
                default:
                    throw new ArgumentException( "Argument_InvalidSeekOrigin" );
            }
            return (long)_position;
        }

        public override void SetLength( long value )
        {
            if( value > 0x7fffffff - _origin )
                throw new ArgumentOutOfRangeException( "value", "ArgumentOutOfRange_StreamLength" );
            int num = _origin + (int)value;
            if( !EnsureCapacity( num ) && num > _length )
                Array.Clear( _buffer, _length, num - _length );

            _length = num;
            if( _position > num )
                _position = num;
        }

        public override void Write( byte[] buffer, int offset, int count )
        {
            int num = _position + count;
            if( num > _length )
            {
                bool flag = _position > _length;
                if( num > _capacity && EnsureCapacity( num ) )
                    flag = false;
                if( flag )
                    Array.Clear( _buffer, _length, num - _length );
                _length = num;
            }
            if( count <= 8 && buffer != _buffer )
            {
                int num2 = count;
                while( --num2 >= 0 )
                    _buffer[_position + num2] = buffer[offset + num2];
            }
            else
                Array.Copy( buffer, offset, _buffer, _position, count );
            _position = num;
        }

        public override void WriteByte( byte value )
        {
            if( _position >= _length )
            {
                int num   = _position + 1;
                bool flag = _position > _length;
                if( num >= _capacity && EnsureCapacity( num ) )
                    flag = false;
                if( flag )
                    Array.Clear( _buffer, _length, _position - _length );
                _length = num;
            }
            _buffer[_position++] = value;
        }

        public override bool CanRead
        {
            get { return true; }
        }

        public override bool CanSeek
        {
            get { return true; }
        }

        public override bool CanWrite
        {
            get { return true; }
        }

        public virtual int Capacity
        {
            get { return _capacity - _origin; }
            set
            {
                if( value != _capacity )
                {
                    if( value > 0 )
                    {
                        byte[] dst = new byte[value];
                        if( _length > 0 )
                            Array.Copy( _buffer, 0, dst, 0, _length );
                        _buffer = dst;
                    }
                    else
                        _buffer = null;
                    _capacity = value;
                }
            }
        }

        public override long Length
        {
            get { return (long)(_length - _origin); }
        }

        public override long Position
        {
            get { return (long)(_position - _origin); }
            set { _position = _origin + ((int)value); }
        }

        internal void Write7BitEncodedInt( int value )
        {
            BinWriter.Write7BitEncodedInt( this, value );
        }

        internal int Read7BitEncodedInt()
        {
            return BinReader.Read7BitEncodedInt( this );
        }
    }

  任何想用这个工具进行序列化的类，只需要实现下面的借口：

public abstract BinSerializer
{
    // 将各成员的数据写入 stream，这是一个辅助函数，派生类一般不需要重载
    public virtual void ToStream( MemStream stream )
    {
        ToBinary( new BinWriter( stream, Encoding.UTF8 ) );
    }

    // 从 stream 中读取各成员的数据，这是一个辅助函数，派生类一般不需要重载
    public virtual void FromStream( MemStream stream )
    {
        FromBinary( new BinReader( stream, Encoding.UTF8 ) );
    }

    protected abstract void ToBinary( BinWriter bw ); // 派生类实现此函数
    protected abstract void FromBinary( BinReader br ); // 派生类实现此函数

}

举个例子：

public class MyTest :?BinSerializer

{
    public int  x;
    public bool y;
    public string z;
    public DateTime dt;
? ?
    protected overide void ToBinary( BinWriter bw )?// 派生类实现此函数

    {
        bw.Write( x );
        bw.Write( y );
        bw.Write( z );
        bw.Write( dt );
    }

? ? protected overide void FromBinary( BinReader br ) // 派生类实现此函数
    {
        x = br.ReadInt32();
        y = br.ReadBool();
        z = br.ReadString();
        dt = br.ReadDate();
    }
}

using( MemStream stream = new MemStream() )

{

    MyTest tester = new?MyTest();

    tester.ToStream( stream ); // 将各成员的数据写入 stream

    stream.Position = 0;? // 将流的位置 Seek 到 Beginning，下面将从它读取数据

    MyTest newTester = new?MyTest();?

    newTester.FromStream(?stream );?// 从 stream 中读取各成员的数据
}

  虽然没有 C# 的?[Serializable] 类属性来得简单，但这对各平台互操作有利。是?[Serializable] 和 Json 之间的一种折中方案。

  同时，它不会引入一堆 Json 和 XML 中的描述标签，而是直接反映内存数据。确保各个成员的读写顺序一致，并确保各个平台的 int, long, uint, ulong 的字节数一致，就可以交互

原文地址：https://blog.51cto.com/14464735/2422927