/// <summary>
/// 保存请求中的文件流
/// </summary>
/// <param name="fileUploadRequest"></param>
/// <param name="rootPath"></param>
/// <param name="encoding"></param>
/// <returns></returns>
public static HttpFile SaveFile(HttpListenerRequest fileUploadRequest, string rootPath, Encoding encoding)
{
HttpFile uploadFile = null;
//判断上传文件大小，默认大小不能超过50M
long contentLength = Convert.ToInt64(fileUploadRequest.Headers["Content-Length"]);
if (contentLength > 1024 * 1024 * 50)
Log.Comment(CommentType.Error, "上传文件大小不能超过50M，文件上传失败！");
else if (rootPath == null)
Log.Comment(CommentType.Error, "文件存放路径未设置，文件上传失败！");
else
{
//获取文件分隔符
string boundary = fileUploadRequest.ContentType.Split(';')[1];
int endBoundaryLength = boundary.Length - 6;
byte[] buffer = new byte[1024]; //缓冲数组，可设定任意大小，设定过小可能导致文件上传速度慢
int headLength = 0; //上传文件头信息长度
int singleReadLength = 0; //单次输入流中读取的长度
int bufferLength = 0; //当前buffer使用的长度
bufferLength = singleReadLength = fileUploadRequest.InputStream.Read(buffer, 0, buffer.Length);
int startPos = -1;
byte[] headByte = new byte[2048]; //文件头长度默认大小，假定文件头部最大长度不超过2048
if (singleReadLength < 1)
Log.Comment(CommentType.Error, "文件流读取失败！");
while (singleReadLength > 0)
{
//找到文件主体部分分隔符，两个换行符，字节数组为{13,10,13,10}
startPos = IndexOf(buffer, bufferLength, new byte[4] { 13, 10, 13, 10 });
if (startPos >= 0)
{
Array.Copy(buffer, 0, headByte, headLength, startPos);
headLength += startPos;
string headString = encoding.GetString(headByte, 0, headLength);
string contentDisposition = headString.Split('\n')[1];
uploadFile = new HttpFile();
int posFileName = contentDisposition.IndexOf("filename=");
uploadFile.OriginName = contentDisposition.Substring(posFileName + 10, contentDisposition.Length - posFileName - 12);
int posPoint = uploadFile.OriginName.LastIndexOf('.');
string fileExtention = posPoint > -1 ? uploadFile.OriginName.Substring(posPoint) : null; //文件扩展名
//生成guid命名文件，防止服务器文件重名
string subFolder = DateTime.Now.ToShortDateString();
uploadFile.RelativePath = Path.Combine(subFolder, Guid.NewGuid().ToString() + fileExtention);
string completePath = Path.Combine(rootPath, subFolder);
if (!Directory.Exists(completePath))
Directory.CreateDirectory(completePath);
using (FileStream saveStream = new FileStream(Path.Combine(rootPath, uploadFile.RelativePath), FileMode.Create, FileAccess.Write))
{
//数据流总长度，去掉头部和分隔符和文件结束边界和当前读取的文件数据部分，就是剩余要读取的文件数据部分长度
//int remainFileLength = (int)contentLength - (headLength + 4 + endBoundaryLength) - (bufferLength - startPos - 4);
int remainFileLength = (int)contentLength - headLength - endBoundaryLength - bufferLength + startPos;
int fileStartPos = startPos + 4;
saveStream.Write(buffer, fileStartPos, bufferLength - fileStartPos);
while (remainFileLength > 0)
{
singleReadLength = fileUploadRequest.InputStream.Read(buffer, 0, buffer.Length < remainFileLength ? buffer.Length : remainFileLength);
saveStream.Write(buffer, 0, singleReadLength);
remainFileLength -= singleReadLength;
}
//此时，文件数据部分已经读取完毕，数据流中还有文件结束边界没读取，此时没必要继续读，直接把singleReadLength设为0，结束循环
singleReadLength = 0;
}
}
else
{
//最后三个字符中可能含有分隔符，所以拷贝长度为当前读取长度减3
int copyLength = bufferLength - 3;
Array.Copy(buffer, 0, headByte, headLength, copyLength);
headLength += copyLength;
//最后三个字符不足匹配长度，放到新的缓冲里面继续匹配
buffer[0] = buffer[bufferLength - 3];
buffer[1] = buffer[bufferLength - 2];
buffer[2] = buffer[bufferLength - 1];
singleReadLength = fileUploadRequest.InputStream.Read(buffer, 3, buffer.Length - 3);
bufferLength = singleReadLength + 3;
}
}
}
return uploadFile;
}