我正在尝试从我的网络服务器检索上传的文件。当客户端通过webform（随机文件）发送文件时，我需要解析请求以获取文件并进一步处理。 基本上，代码如下：
HttpListenerContext context = listener.GetContext();
HttpListenerRequest request = context.Request;
StreamReader r = new StreamReader(request.InputStream, System.Text.Encoding.Default);
// this is the retrieved file from streamreader
string file = null;
while ((line = r.ReadLine()) != null){
// i read the stream till i retrieve the filename
// get the file data out and break the loop
}
// A byststream is created by converting the string,
Byte[] bytes = request.ContentEncoding.GetBytes(file);
MemoryStream mstream = new MemoryStream(bytes);
// do the rest
因此，我能够检索文本文件，但对于所有其他文件，它们都已损坏。 有人能告诉我如何正确解析这些HttplistnerRequests（或提供一个轻量级的替代方案）吗？
答案 0 :(得分：15)
我认为通过使用HttpListener而不是使用ASP.Net的内置工具，您在使自己的工作变得更加困难。但是如果你必须这样做，这里有一些示例代码。注意：1）我假设您在enctype="multipart/form-data"上使用<form>。 2）此代码旨在与仅包含<input type="file" />的表单一起使用，如果您要发布其他字段或您需要更改代码的多个文件。 3）这是一个概念/示例的证明，它可能有错误，并且不是特别灵活。
static void Main(string[] args)
{
HttpListener listener = new HttpListener();
listener.Prefixes.Add("http://localhost:8080/ListenerTest/");
listener.Start();
HttpListenerContext context = listener.GetContext();
SaveFile(context.Request.ContentEncoding, GetBoundary(context.Request.ContentType), context.Request.InputStream);
context.Response.StatusCode = 200;
context.Response.ContentType = "text/html";
using (StreamWriter writer = new StreamWriter(context.Response.OutputStream, Encoding.UTF8))
writer.WriteLine("File Uploaded");
context.Response.Close();
listener.Stop();
}
private static String GetBoundary(String ctype)
{
return "--" + ctype.Split(';')[1].Split('=')[1];
}
private static void SaveFile(Encoding enc, String boundary, Stream input)
{
Byte[] boundaryBytes = enc.GetBytes(boundary);
Int32 boundaryLen = boundaryBytes.Length;
using (FileStream output = new FileStream("data", FileMode.Create, FileAccess.Write))
{
Byte[] buffer = new Byte[1024];
Int32 len = input.Read(buffer, 0, 1024);
Int32 startPos = -1;
// Find start boundary
while (true)
{
if (len == 0)
{
throw new Exception("Start Boundaray Not Found");
}
startPos = IndexOf(buffer, len, boundaryBytes);
if (startPos >= 0)
{
break;
}
else
{
Array.Copy(buffer, len - boundaryLen, buffer, 0, boundaryLen);
len = input.Read(buffer, boundaryLen, 1024 - boundaryLen);
}
}
// Skip four lines (Boundary, Content-Disposition, Content-Type, and a blank)
for (Int32 i = 0; i < 4; i++)
{
while (true)
{
if (len == 0)
{
throw new Exception("Preamble not Found.");
}
startPos = Array.IndexOf(buffer, enc.GetBytes("\n")[0], startPos);
if (startPos >= 0)
{
startPos++;
break;
}
else
{
len = input.Read(buffer, 0, 1024);
}
}
}
Array.Copy(buffer, startPos, buffer, 0, len - startPos);
len = len - startPos;
while (true)
{
Int32 endPos = IndexOf(buffer, len, boundaryBytes);
if (endPos >= 0)
{
if (endPos > 0) output.Write(buffer, 0, endPos-2);
break;
}
else if (len <= boundaryLen)
{
throw new Exception("End Boundaray Not Found");
}
else
{
output.Write(buffer, 0, len - boundaryLen);
Array.Copy(buffer, len - boundaryLen, buffer, 0, boundaryLen);
len = input.Read(buffer, boundaryLen, 1024 - boundaryLen) + boundaryLen;
}
}
}
}
private static Int32 IndexOf(Byte[] buffer, Int32 len, Byte[] boundaryBytes)
{
for (Int32 i = 0; i <= len - boundaryBytes.Length; i++)
{
Boolean match = true;
for (Int32 j = 0; j < boundaryBytes.Length && match; j++)
{
match = buffer[i + j] == boundaryBytes[j];
}
if (match)
{
return i;
}
}
return -1;
}
为了帮助您更好地理解上面代码的作用，这里是HTTP POST的主体：
Content-Type: multipart/form-data; boundary=----WebKitFormBoundary9lcB0OZVXSqZLbmv
------WebKitFormBoundary9lcB0OZVXSqZLbmv
Content-Disposition: form-data; name="my_file"; filename="Test.txt"
Content-Type: text/plain
Test
------WebKitFormBoundary9lcB0OZVXSqZLbmv--
我遗漏了不相关的标题。如您所见，您需要通过扫描来解析主体以查找开始和结束边界序列，并删除文件内容之前的子标题。遗憾的是，由于二进制数据的可能性，您无法使用StreamReader。同样不幸的是每个文件没有Content-Length（请求的Content-Length标头指定了主体的总长度，包括边界，子标题和间距。
答案 1 :(得分：1)
问题是您正在以文本形式阅读文件。
您需要将文件读取为bytearray而使用BinaryReader比StreamReader更好，更易于使用：
Byte[] bytes;
using (System.IO.BinaryReader r = new System.IO.BinaryReader(request.InputStream))
{
// Read the data from the stream into the byte array
bytes = r.ReadBytes(Convert.ToInt32(request.InputStream.Length));
}
MemoryStream mstream = new MemoryStream(bytes);
答案 2 :(得分：1)
可能有虫子，彻底测试。这个获取所有发布，获取和文件。
using System.Collections.Generic;
using System.Collections.Specialized;
using System.IO;
using System.Net;
using System.Text;
using System.Web;
namespace DUSTLauncher
{
class HttpNameValueCollection
{
public class File
{
private string _fileName;
public string FileName { get { return _fileName ?? (_fileName = ""); } set { _fileName = value; } }
private string _fileData;
public string FileData { get { return _fileData ?? (_fileName = ""); } set { _fileData = value; } }
private string _contentType;
public string ContentType { get { return _contentType ?? (_contentType = ""); } set { _contentType = value; } }
}
private NameValueCollection _get;
private Dictionary<string, File> _files;
private readonly HttpListenerContext _ctx;
public NameValueCollection Get { get { return _get ?? (_get = new NameValueCollection()); } set { _get = value; } }
public NameValueCollection Post { get { return _ctx.Request.QueryString; } }
public Dictionary<string, File> Files { get { return _files ?? (_files = new Dictionary<string, File>()); } set { _files = value; } }
private void PopulatePostMultiPart(string post_string)
{
var boundary_index = _ctx.Request.ContentType.IndexOf("boundary=") + 9;
var boundary = _ctx.Request.ContentType.Substring(boundary_index, _ctx.Request.ContentType.Length - boundary_index);
var upper_bound = post_string.Length - 4;
if (post_string.Substring(2, boundary.Length) != boundary)
throw (new InvalidDataException());
var raw_post_strings = new List<string>();
var current_string = new StringBuilder();
for (var x = 4 + boundary.Length; x < upper_bound; ++x)
{
if (post_string.Substring(x, boundary.Length) == boundary)
{
x += boundary.Length + 1;
raw_post_strings.Add(current_string.ToString().Remove(current_string.Length - 3, 3));
current_string.Clear();
continue;
}
current_string.Append(post_string[x]);
var post_variable_string = current_string.ToString();
var end_of_header = post_variable_string.IndexOf("\r\n\r\n");
if (end_of_header == -1) throw (new InvalidDataException());
var filename_index = post_variable_string.IndexOf("filename=\"", 0, end_of_header);
var filename_starts = filename_index + 10;
var content_type_starts = post_variable_string.IndexOf("Content-Type: ", 0, end_of_header) + 14;
var name_starts = post_variable_string.IndexOf("name=\"") + 6;
var data_starts = end_of_header + 4;
if (filename_index == -1) continue;
var filename = post_variable_string.Substring(filename_starts, post_variable_string.IndexOf("\"", filename_starts) - filename_starts);
var content_type = post_variable_string.Substring(content_type_starts, post_variable_string.IndexOf("\r\n", content_type_starts) - content_type_starts);
var file_data = post_variable_string.Substring(data_starts, post_variable_string.Length - data_starts);
var name = post_variable_string.Substring(name_starts, post_variable_string.IndexOf("\"", name_starts) - name_starts);
Files.Add(name, new File() { FileName = filename, ContentType = content_type, FileData = file_data });
continue;
}
}
private void PopulatePost()
{
if (_ctx.Request.HttpMethod != "POST" || _ctx.Request.ContentType == null) return;
var post_string = new StreamReader(_ctx.Request.InputStream, _ctx.Request.ContentEncoding).ReadToEnd();
if (_ctx.Request.ContentType.StartsWith("multipart/form-data"))
PopulatePostMultiPart(post_string);
else
Get = HttpUtility.ParseQueryString(post_string);
}
public HttpNameValueCollection(ref HttpListenerContext ctx)
{
_ctx = ctx;
PopulatePost();
}
}
}
答案 3 :(得分：0)
我喜欢@ paul-wheeler的答案。但是，我需要修改其代码以包含一些其他数据（在这种情况下，为目录结构）。
我正在使用此代码上传文件：
var myDropzone = $("#fileDropZone");
myDropzone.dropzone(
{
url: "http://" + self.location.hostname + "/Path/Files.html,
method: "post",
createImageThumbnails: true,
previewTemplate: document.querySelector('#previewTemplateId').innerHTML,
clickable: false,
init: function () {
this.on('sending', function(file, xhr, formData){
// xhr is XMLHttpRequest
var name = file.fullPath;
if (typeof (file.fullPath) === "undefined") {
name = file.name;
}
formData.append('fileNameWithPath', name);
});
}
});
这是@ paul-wheeler修改的代码。谢谢@ paul-wheeler。
public class FileManager
{
public static void SaveFile(HttpListenerRequest request, string savePath)
{
var tempFileName = Path.Combine(savePath, $"{DateTime.Now.Ticks}.tmp");
if (!Directory.Exists(savePath))
{
Directory.CreateDirectory(savePath);
}
var (res, fileName) = SaveTmpFile(request, tempFileName);
if (res)
{
var filePath = Path.Combine(savePath, fileName);
var fileDir = filePath.Substring(0, filePath.LastIndexOf(Path.DirectorySeparatorChar));
if (!Directory.Exists(fileDir))
{
Directory.CreateDirectory(fileDir);
}
if (File.Exists(filePath))
{
File.Delete(filePath);
}
File.Move(tempFileName, filePath);
}
}
private static (bool, string) SaveTmpFile(HttpListenerRequest request, string tempFileName)
{
var enc = request.ContentEncoding;
var boundary = GetBoundary(request.ContentType);
var input = request.InputStream;
byte[] boundaryBytes = enc.GetBytes(boundary);
var boundaryLen = boundaryBytes.Length;
using (FileStream output = new FileStream(tempFileName, FileMode.Create, FileAccess.Write))
{
var buffer = new byte[1024];
var len = input.Read(buffer, 0, 1024);
var startPos = -1;
// Get file name and relative path
var strBuffer = Encoding.Default.GetString(buffer);
var strStart = strBuffer.IndexOf("fileNameWithPath") + 21;
if (strStart < 21)
{
Logger.LogError("File name not found");
return (false, null);
}
var strEnd = strBuffer.IndexOf(boundary, strStart) - 2;
var fileName = strBuffer.Substring(strStart, strEnd - strStart);
fileName = fileName.Replace('/', Path.DirectorySeparatorChar);
// Find start boundary
while (true)
{
if (len == 0)
{
Logger.LogError("Find start boundary not found");
return (false, null);
}
startPos = IndexOf(buffer, len, boundaryBytes);
if (startPos >= 0)
{
break;
}
else
{
Array.Copy(buffer, len - boundaryLen, buffer, 0, boundaryLen);
len = input.Read(buffer, boundaryLen, 1024 - boundaryLen);
}
}
// Advance to data
var foundData = false;
while (!foundData)
{
while (true)
{
if (len == 0)
{
Logger.LogError("Preamble not Found");
return (false, null);
}
startPos = Array.IndexOf(buffer, enc.GetBytes("\n")[0], startPos);
if (startPos >= 0)
{
startPos++;
break;
}
else
{
// In case read in line is longer than buffer
len = input.Read(buffer, 0, 1024);
}
}
var currStr = Encoding.Default.GetString(buffer).Substring(startPos);
if (currStr.StartsWith("Content-Type:"))
{
// Go past the last carriage-return\line-break. (\r\n)
startPos = Array.IndexOf(buffer, enc.GetBytes("\n")[0], startPos) + 3;
break;
}
}
Array.Copy(buffer, startPos, buffer, 0, len - startPos);
len = len - startPos;
while (true)
{
var endPos = IndexOf(buffer, len, boundaryBytes);
if (endPos >= 0)
{
if (endPos > 0) output.Write(buffer, 0, endPos - 2);
break;
}
else if (len <= boundaryLen)
{
Logger.LogError("End Boundaray Not Found");
return (false, null);
}
else
{
output.Write(buffer, 0, len - boundaryLen);
Array.Copy(buffer, len - boundaryLen, buffer, 0, boundaryLen);
len = input.Read(buffer, boundaryLen, 1024 - boundaryLen) + boundaryLen;
}
}
return (true, fileName);
}
}
private static int IndexOf(byte[] buffer, int len, byte[] boundaryBytes)
{
for (int i = 0; i <= len - boundaryBytes.Length; i++)
{
var match = true;
for (var j = 0; j < boundaryBytes.Length && match; j++)
{
match = buffer[i + j] == boundaryBytes[j];
}
if (match)
{
return i;
}
}
return -1;
}
private static string GetBoundary(string ctype)
{
return "--" + ctype.Split(';')[1].Split('=')[1];
}
}