具有多个文件的WCF多部分/表单数据 [英] WCF multipart/form data with multiple files

问题描述

在任何地方都找不到有关如何处理请求中包含多个文件的多部分/表单数据的示例.

I can't find any examples anywhere on how to process multipart/form data which contains multiple files in the request.

我正在尝试构建一个WCF服务端点，该端点在一个文本文件中包含一组参数，然后在两个图像文件中包含一组参数，所有这些都包括一个帖子中的三个文件.使用Fiddler，我可以构建请求，它看起来像这样:

I'm trying to build a WCF service endpoint which contains a set of parameters in a text file, and then two image files, all in all including three files in one post. Using Fiddler, I am able to build the request and it looks like this:

HEADERS: Content-Type: multipart/form-data; boundary=-------------------------acebdf13572468
         User-Agent: Fiddler
         Host: dhiibews.brandonb.com
         Content-Length: 107865
REQUESTBODY: ---------------------------acebdf13572468
             Content-Disposition: form-data; name="Json"; filename="depositcheckrequest.txt"
             Content-Type: application/json

             <@INCLUDE *C:\depositcheckrequest.txt*@>
             ---------------------------acebdf13572468
             Content-Disposition: form-data; name="frontImage"; filename="front.jpg"
             Content-Type: image/jpeg

             <@INCLUDE *C:\front.jpg*@>
             ---------------------------acebdf13572468
             Content-Disposition: form-data; name="rearImage"; filename="rear.jpg"
             Content-Type: image/jpeg

             <@INCLUDE *C:\rear.jpg*@>
             ---------------------------acebdf13572468--

include标记基本上最终会将文件内容作为原始数据吐出来.

The include tags basically end up spitting out the file content as raw data.

我一直在搜索，所有能找到的人都可以告诉我如何获取一个文件的信息，在我看来，该文件最终是第一个文件.我不想只得到一个文件.如您所见，我正在尝试上传三个文件.

I've been searching and all I can find are people who can tell me how to get the information for one file which in my case ends up being the first one. I don't want to get just one file though; as you can see I am trying to upload THREE files.

如何在单个multipart/form数据POST请求中解析多个文件?

How do I parse multiple files in a single multipart/form data POST request?

推荐答案

好，我想出了一个解决方案.事实证明，框架 Nancyfx 包含一个由多部分组成的数据处理器，用于分隔边界进入子流.因此，我从Nancy的源代码中窃取了相关文件，并将其复制到我的项目中.相关文件为:

Ok I figured out a solution. It turns out that the framework Nancyfx includes a multipart data processor which separates the boundaries for you into substreams. So I stole the relevant files from Nancy's source code and copied them into my project. The relevant files are:

HttpMultipart.cs:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;

namespace MyProjectNamespace
{
    using System.Collections.Generic;
    using System.IO;
    using System.Linq;
    using System.Text;

    /// <summary>
    /// Retrieves <see cref="HttpMultipartBoundary"/> instances from a request stream.
    /// </summary>
    public class HttpMultipart
    {
        private const byte LF = (byte)'\n';
        private readonly byte[] boundaryAsBytes;
        private readonly HttpMultipartBuffer readBuffer;
        private readonly MemoryStream requestStream;
        private readonly byte[] closingBoundaryAsBytes;

        /// <summary>
        /// Initializes a new instance of the <see cref="HttpMultipart"/> class.
        /// </summary>
        /// <param name="requestStream">The request stream to parse.</param>
        /// <param name="boundary">The boundary marker to look for.</param>
        public HttpMultipart(Stream requestStream, string boundary)
        {
            this.requestStream = new MemoryStream(ToByteArray(requestStream));
            this.boundaryAsBytes = GetBoundaryAsBytes(boundary, false);
            this.closingBoundaryAsBytes = GetBoundaryAsBytes(boundary, true);
            this.readBuffer = new HttpMultipartBuffer(this.boundaryAsBytes, this.closingBoundaryAsBytes);
        }

        /// <summary>
        /// Gets the <see cref="HttpMultipartBoundary"/> instances from the request stream.
        /// </summary>
        /// <returns>An <see cref="IEnumerable{T}"/> instance, containing the found <see cref="HttpMultipartBoundary"/> instances.</returns>
        public IEnumerable<HttpMultipartBoundary> GetBoundaries()
        {
            return
                (from boundaryStream in this.GetBoundarySubStreams()
                 select new HttpMultipartBoundary(boundaryStream)).ToList();
        }

        private static byte[] GetBoundaryAsBytes(string boundary, bool closing)
        {
            var boundaryBuilder = new StringBuilder();

            boundaryBuilder.Append("--");
            boundaryBuilder.Append(boundary);

            if (closing)
            {
                boundaryBuilder.Append("--");
            }
            else
            {
                boundaryBuilder.Append('\r');
                boundaryBuilder.Append('\n');
            }

            var bytes =
                Encoding.ASCII.GetBytes(boundaryBuilder.ToString());

            return bytes;
        }

        private IEnumerable<HttpMultipartSubStream> GetBoundarySubStreams()
        {
            var boundarySubStreams = new List<HttpMultipartSubStream>();
            var boundaryStart = this.GetNextBoundaryPosition();

            while (MultipartIsNotCompleted(boundaryStart))
            {
                var boundaryEnd = this.GetNextBoundaryPosition();
                boundarySubStreams.Add(new HttpMultipartSubStream(
                    this.requestStream,
                    boundaryStart,
                    this.GetActualEndOfBoundary(boundaryEnd)));

                boundaryStart = boundaryEnd;
            }

            return boundarySubStreams;
        }

        private bool MultipartIsNotCompleted(long boundaryPosition)
        {
            return boundaryPosition > -1 && !this.readBuffer.IsClosingBoundary;
        }

        //we add two because or the \r\n before the boundary
        private long GetActualEndOfBoundary(long boundaryEnd)
        {
            if (this.CheckIfFoundEndOfStream())
            {
                return this.requestStream.Position - (this.readBuffer.Length + 2);
            }
            return boundaryEnd - (this.readBuffer.Length + 2);
        }

        private bool CheckIfFoundEndOfStream()
        {
            return this.requestStream.Position.Equals(this.requestStream.Length);
        }

        private long GetNextBoundaryPosition()
        {
            this.readBuffer.Reset();
            while (true)
            {
                var byteReadFromStream = this.requestStream.ReadByte();

                if (byteReadFromStream == -1)
                {
                    return -1;
                }

                this.readBuffer.Insert((byte)byteReadFromStream);

                if (this.readBuffer.IsFull && (this.readBuffer.IsBoundary || this.readBuffer.IsClosingBoundary))
                {
                    return this.requestStream.Position;
                }

                if (byteReadFromStream.Equals(LF) || this.readBuffer.IsFull)
                {
                    this.readBuffer.Reset();
                }
            }
        }

        private byte[] ToByteArray(Stream stream)
        {
            byte[] buffer = new byte[32768];
            using (MemoryStream ms = new MemoryStream())
            {
                while (true)
                {
                    int read = stream.Read(buffer, 0, buffer.Length);
                    if (read <= 0)
                    {
                        return ms.ToArray();
                    }
                    ms.Write(buffer, 0, read);
                }
            }
        }
    }
}

HttpMultipartBuffer.cs:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;

namespace MyProjectNamespace
{
    public class HttpMultipartBuffer
    {
        private readonly byte[] boundaryAsBytes;
        private readonly byte[] closingBoundaryAsBytes;
        private readonly byte[] buffer;
        private int position;

        /// <summary>
        /// Initializes a new instance of the <see cref="HttpMultipartBuffer"/> class.
        /// </summary>
        /// <param name="boundaryAsBytes">The boundary as a byte-array.</param>
        /// <param name="closingBoundaryAsBytes">The closing boundary as byte-array</param>
        public HttpMultipartBuffer(byte[] boundaryAsBytes, byte[] closingBoundaryAsBytes)
        {
            this.boundaryAsBytes = boundaryAsBytes;
            this.closingBoundaryAsBytes = closingBoundaryAsBytes;
            this.buffer = new byte[this.boundaryAsBytes.Length];
        }

        /// <summary>
        /// Gets a value indicating whether the buffer contains the same values as the boundary.
        /// </summary>
        /// <value><see langword="true"/> if buffer contains the same values as the boundary; otherwise, <see langword="false"/>.</value>
        public bool IsBoundary
        {
            get { return this.buffer.SequenceEqual(this.boundaryAsBytes); }
        }

        public bool IsClosingBoundary
        {
            get { return this.buffer.SequenceEqual(this.closingBoundaryAsBytes); }
        }

        /// <summary>
        /// Gets a value indicating whether this buffer is full.
        /// </summary>
        /// <value><see langword="true"/> if buffer is full; otherwise, <see langword="false"/>.</value>
        public bool IsFull
        {
            get { return this.position.Equals(this.buffer.Length); }
        }

        /// <summary>
        /// Gets the the number of bytes that can be stored in the buffer.
        /// </summary>
        /// <value>The number of butes that can be stored in the buffer.</value>
        public int Length
        {
            get { return this.buffer.Length; }
        }

        /// <summary>
        /// Resets the buffer so that inserts happens from the start again.
        /// </summary>
        /// <remarks>This does not clear any previously written data, just resets the buffer position to the start. Data that is inserted after Reset has been called will overwrite old data.</remarks>
        public void Reset()
        {
            this.position = 0;
        }

        /// <summary>
        /// Inserts the specified value into the buffer and advances the internal position.
        /// </summary>
        /// <param name="value">The value to insert into the buffer.</param>
        /// <remarks>This will throw an <see cref="ArgumentOutOfRangeException"/> is you attempt to call insert more times then the <see cref="Length"/> of the buffer and <see cref="Reset"/> was not invoked.</remarks>
        public void Insert(byte value)
        {
            this.buffer[this.position++] = value;
        }
    }
}

HttpMultipartBoundary.cs:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;
using System.Web;

namespace DHIWebSvc.Models
{
    public class HttpMultipartBoundary
    {
        private const byte LF = (byte)'\n';
        private const byte CR = (byte)'\r';

        /// <summary>
        /// Initializes a new instance of the <see cref="HttpMultipartBoundary"/> class.
        /// </summary>
        /// <param name="boundaryStream">The stream that contains the boundary information.</param>
        public HttpMultipartBoundary(HttpMultipartSubStream boundaryStream)
        {
            this.Value = boundaryStream;
            this.ExtractHeaders();
        }

        /// <summary>
        /// Gets the contents type of the boundary value.
        /// </summary>
        /// <value>A <see cref="string"/> containing the name of the value if it is available; otherwise <see cref="string.Empty"/>.</value>
        public string ContentType { get; private set; }

        /// <summary>
        /// Gets or the filename for the boundary value.
        /// </summary>
        /// <value>A <see cref="string"/> containing the filename value if it is available; otherwise <see cref="string.Empty"/>.</value>
        /// <remarks>This is the RFC2047 decoded value of the filename attribute of the Content-Disposition header.</remarks>
        public string Filename { get; private set; }

        /// <summary>
        /// Gets name of the boundary value.
        /// </summary>
        /// <remarks>This is the RFC2047 decoded value of the name attribute of the Content-Disposition header.</remarks>
        public string Name { get; private set; }

        /// <summary>
        /// A stream containig the value of the boundary.
        /// </summary>
        /// <remarks>This is the RFC2047 decoded value of the Content-Type header.</remarks>
        public HttpMultipartSubStream Value { get; private set; }

        private void ExtractHeaders()
        {
            while (true)
            {
                var header =
                    this.ReadLineFromStream();

                if (string.IsNullOrEmpty(header))
                {
                    break;
                }

                if (header.StartsWith("Content-Disposition", StringComparison.CurrentCultureIgnoreCase))
                {
                    this.Name = Regex.Match(header, @"name=""(?<name>[^\""]*)", RegexOptions.IgnoreCase).Groups["name"].Value;
                    this.Filename = Regex.Match(header, @"filename=""(?<filename>[^\""]*)", RegexOptions.IgnoreCase).Groups["filename"].Value;
                }

                if (header.StartsWith("Content-Type", StringComparison.InvariantCultureIgnoreCase))
                {
                    this.ContentType = header.Split(new[] { ' ' }).Last().Trim();
                }
            }

            this.Value.PositionStartAtCurrentLocation();
        }

        private string ReadLineFromStream()
        {
            var readBuffer = new StringBuilder();

            while (true)
            {
                var byteReadFromStream = this.Value.ReadByte();

                if (byteReadFromStream == -1)
                {
                    return null;
                }

                if (byteReadFromStream.Equals(LF))
                {
                    break;
                }

                readBuffer.Append((char)byteReadFromStream);
            }

            var lineReadFromStream =
                readBuffer.ToString().Trim(new[] { (char)CR });

            return lineReadFromStream;
        }
    }
}

最后...

HttpMultipartSubStream.cs:

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Web;

namespace DHIWebSvc.Models
{
    public class HttpMultipartSubStream : Stream
    {
        private readonly Stream stream;
        private readonly long end;
        private long start;
        private long position;

        /// <summary>
        /// Initializes a new instance of the <see cref="HttpMultipartSubStream"/> class.
        /// </summary>
        /// <param name="stream">The stream to create the sub-stream ontop of.</param>
        /// <param name="start">The start offset on the parent stream where the sub-stream should begin.</param>
        /// <param name="end">The end offset on the parent stream where the sub-stream should end.</param>
        public HttpMultipartSubStream(Stream stream, long start, long end)
        {
            this.stream = stream;
            this.start = start;
            this.position = start;
            this.end = end;
        }

        /// <summary>
        /// When overridden in a derived class, gets a value indicating whether the current stream supports reading.
        /// </summary>
        /// <returns><see langword="true"/> if the stream supports reading; otherwise, <see langword="false"/>.</returns>
        public override bool CanRead
        {
            get { return true; }
        }

        /// <summary>
        /// When overridden in a derived class, gets a value indicating whether the current stream supports seeking.
        /// </summary>
        /// <returns><see langword="true"/> if the stream supports seeking; otherwise, <see langword="false"/>.</returns>
        public override bool CanSeek
        {
            get { return true; }
        }

        /// <summary>
        /// When overridden in a derived class, gets a value indicating whether the current stream supports writing.
        /// </summary>
        /// <returns><see langword="true"/> if the stream supports writing; otherwise, <see langword="false"/>.</returns>
        public override bool CanWrite
        {
            get { return false; }
        }

        /// <summary>
        /// When overridden in a derived class, gets the length in bytes of the stream.
        /// </summary>
        /// <returns>A long value representing the length of the stream in bytes.</returns>
        /// <exception cref="NotSupportedException">A class derived from Stream does not support seeking. </exception><exception cref="T:System.ObjectDisposedException">Methods were called after the stream was closed.</exception>
        public override long Length
        {
            get 
            { 
                return this.end - this.start; 
            }
        }

        /// <summary>
        /// When overridden in a derived class, gets or sets the position within the current stream.
        /// </summary>
        /// <returns>
        /// The current position within the stream.
        /// </returns>
        /// <exception cref="T:System.IO.IOException">An I/O error occurs. </exception><exception cref="T:System.NotSupportedException">The stream does not support seeking. </exception><exception cref="T:System.ObjectDisposedException">Methods were called after the stream was closed. </exception><filterpriority>1</filterpriority>
        public override long Position
        {
            get { return this.position - this.start; }
            set { this.position = this.Seek(value, SeekOrigin.Begin); }
        }

        public void PositionStartAtCurrentLocation()
        {
            this.start = this.stream.Position;
        }

        /// <summary>
        /// When overridden in a derived class, clears all buffers for this stream and causes any buffered data to be written to the underlying device.
        /// </summary>
        /// <remarks>In the <see cref="HttpMultipartSubStream"/> type this method is implemented as no-op.</remarks>
        public override void Flush()
        {
        }

        /// <summary>
        /// When overridden in a derived class, reads a sequence of bytes from the current stream and advances the position within the stream by the number of bytes read.
        /// </summary>
        /// <returns>The total number of bytes read into the buffer. This can be less than the number of bytes requested if that many bytes are not currently available, or zero (0) if the end of the stream has been reached. </returns>
        /// <param name="buffer">An array of bytes. When this method returns, the buffer contains the specified byte array with the values between <paramref name="offset"/> and (<paramref name="offset"/> + <paramref name="count"/> - 1) replaced by the bytes read from the current source. </param>
        /// <param name="offset">The zero-based byte offset in <paramref name="buffer"/> at which to begin storing the data read from the current stream.</param>
        /// <param name="count">The maximum number of bytes to be read from the current stream. </param>
        public override int Read(byte[] buffer, int offset, int count)
        {
            if (count > (this.end - this.position))
            {
                count = (int)(this.end - this.position);
            }

            if (count <= 0)
            {
                return 0;
            }

            this.stream.Position = this.position;

            var bytesReadFromStream =
                this.stream.Read(buffer, offset, count);

            this.RepositionAfterRead(bytesReadFromStream);

            return bytesReadFromStream;
        }

        /// <summary>
        /// Reads a byte from the stream and advances the position within the stream by one byte, or returns -1 if at the end of the stream.
        /// </summary>
        /// <returns>The unsigned byte cast to an Int32, or -1 if at the end of the stream.</returns>
        public override int ReadByte()
        {
            if (this.position >= this.end)
            {
                return -1;
            }

            this.stream.Position = this.position;

            var byteReadFromStream = this.stream.ReadByte();

            this.RepositionAfterRead(1);

            return byteReadFromStream;
        }

        /// <summary>
        /// When overridden in a derived class, sets the position within the current stream.
        /// </summary>
        /// <returns>The new position within the current stream.</returns>
        /// <param name="offset">A byte offset relative to the <paramref name="origin"/> parameter.</param>
        /// <param name="origin">A value of type <see cref="SeekOrigin"/> indicating the reference point used to obtain the new position.</param>
        public override long Seek(long offset, SeekOrigin origin)
        {
            var subStreamRelativePosition =
                this.CalculateSubStreamRelativePosition(origin, offset);

            this.ThrowExceptionIsPositionIsOutOfBounds(subStreamRelativePosition);

            this.position = this.stream.Seek(subStreamRelativePosition, SeekOrigin.Begin);

            return this.position;
        }

        /// <summary>
        /// When overridden in a derived class, sets the length of the current stream.
        /// </summary>
        /// <param name="value">The desired length of the current stream in bytes.</param>
        /// <remarks>This will always throw a <see cref="InvalidOperationException"/> for the <see cref="HttpMultipartSubStream"/> type.</remarks>
        public override void SetLength(long value)
        {
            throw new InvalidOperationException();
        }

        /// <summary>
        /// When overridden in a derived class, writes a sequence of bytes to the current stream and advances the current position within this stream by the number of bytes written.
        /// </summary>
        /// <param name="buffer">An array of bytes. This method copies <paramref name="count"/> bytes from <paramref name="buffer"/> to the current stream. </param>
        /// <param name="offset">The zero-based byte offset in <paramref name="buffer"/> at which to begin copying bytes to the current stream. </param>
        /// <param name="count">The number of bytes to be written to the current stream. </param>
        /// <remarks>This will always throw a <see cref="InvalidOperationException"/> for the <see cref="HttpMultipartSubStream"/> type.</remarks>
        public override void Write(byte[] buffer, int offset, int count)
        {
            throw new InvalidOperationException();
        }

        private void ThrowExceptionIsPositionIsOutOfBounds(long subStreamRelativePosition)
        {
            if (subStreamRelativePosition < 0 || subStreamRelativePosition > this.end)
            {
                throw new InvalidOperationException();
            }
        }

        private long CalculateSubStreamRelativePosition(SeekOrigin origin, long offset)
        {
            var subStreamRelativePosition = 0L;

            switch (origin)
            {
                case SeekOrigin.Begin:
                    subStreamRelativePosition = this.start + offset;
                    break;

                case SeekOrigin.Current:
                    subStreamRelativePosition = this.position + offset;
                    break;

                case SeekOrigin.End:
                    subStreamRelativePosition = this.end + offset;
                    break;
            }
            return subStreamRelativePosition;
        }

        private void RepositionAfterRead(int bytesReadFromStream)
        {
            if (bytesReadFromStream == -1)
            {
                this.position = this.end;
            }
            else
            {
                this.position += bytesReadFromStream;
            }
        }
    }
}

对于我想做的事情来说用法相对简单.我只定义了一个边界，仅查找特定的零件名称.因此，对于我的问题中的示例，我将边界"-------------------------acebdf13572468"与三个文件一起使用:Json，frontImage和rearImage.

The usage is relatively simple for what I was trying to do. I simply defined a boundary and only look for specific part names. So for the example in my question, I used the boundary "-------------------------acebdf13572468" with three files: Json, frontImage, and rearImage.

这篇关于具有多个文件的WCF多部分/表单数据的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！