/// <summary>
/// 根据页面对象和上传文件临时目录文件夹，获取一个文件上传上下文类实例
/// </summary>
/// <remarks>用户在页面上传初始化上传会话，要求页面每次刷新时均用此方法初始化一个上传上下文</remarks>
/// <param name="page">页面对象</param>
/// <param name="TempFileDir">文件存放临时文件夹</param>
/// <returns>文件上传上下文</returns>
public static UploadContext InitUploadContext(System.Web.UI.Page page, string TempFileDir)
{
UploadContext context = new UploadContext(page, TempFileDir);
HttpContext.Current.Cache.Add(context.GUID, context, null, DateTime.Now.AddDays(10), TimeSpan.Zero, CacheItemPriority.High, null);
return context;
}
/// <summary>
/// 分析数据，若是文件，则写入文件，在上传上下文件记录参数
/// </summary>
/// <remarks>
/// 算法说明：若上一个文件已结束，一、则查找新文件标志符，没找到则退出，找到又分两种情况：1、文件在当前块内结束，则写文件，关闭文件，回到开始继续查找文件标志，
/// 2、文件在当前块内没结束，则写文件，并退出处理过程
/// 二、上一个文件未结束，则找文件结束标志，然后又分两种情况：1、找到：当前文件结束，写文件，关闭文件，回到开始，继续分析处理数据，
/// 2、没找到，则文件还没结束，则写文件，退出处理过程
/// </remarks>
/// <param name="buffer">数据块</param>
/// <param name="startIndex">有效数据起始索引</param>
/// <param name="maxLength">有效数据结束索引</param>
/// <param name="uploadContext">文件上传处理上下文</param>
/// <returns>应预留数据长度，防止边界（如文件说明，内容分隔符）位于两个数据块中，若不能确定预留长，则预留
/// 全局常量splitLength所指示的长度</returns>
public int ReadData(byte[] buffer, int startIndex, int maxLength, UploadContext uploadContext)
{
while (true)
{
if (m_finished)
{
_fileInfo = GetFileInfo(buffer, startIndex, maxLength);
if ((_fileInfo.PathFileName == null) || (_fileInfo.PathFileName.Trim() == ""))//没有找到文件标志
{
RewriteRequest(buffer, startIndex, maxLength - startIndex - splitLength);
return splitLength;
}
uploadContext.FileConIds = ArrayAddItem(uploadContext.FileConIds, _fileInfo.FileControl);
uploadContext.FileNames = ArrayAddItem(uploadContext.FileNames, _fileInfo.PathFileName);
RewriteRequest(buffer, startIndex, _fileInfo.startIndex - startIndex + 10);
fs = File.Create(uploadContext.TmepFileDir + uploadContext.GUID + uploadContext.FileNames.Length.ToString() + GetFileName(_fileInfo.PathFileName));
if (_fileInfo.endIndex > -1)
{
m_finished = true;
fs.Write(buffer, _fileInfo.startIndex, _fileInfo.endIndex - _fileInfo.startIndex);
fs.Close();
startIndex = _fileInfo.endIndex;
}
else
{
m_finished = false;
if (maxLength - _fileInfo.startIndex > splitLength)
{
fs.Write(buffer, _fileInfo.startIndex, maxLength - _fileInfo.startIndex - splitLength);
return splitLength;
}
else
{
return maxLength - _fileInfo.startIndex; //防止将标志写入了文件
}
}
}
else
{
_fileInfo.endIndex = DestTag(buffer, m_boundary, startIndex, maxLength);
if (_fileInfo.endIndex > -1) //已结束
{
_fileInfo.endIndex -= 2; //去掉数据区后的回车换行符
m_finished = true;
fs.Write(buffer, startIndex, _fileInfo.endIndex - startIndex);
fs.Close();
startIndex = _fileInfo.endIndex;
}
else
{
m_finished = false; //当前数据块中，文件体未结束
if (maxLength - startIndex > splitLength)
{
fs.Write(buffer, startIndex, maxLength - startIndex - splitLength);
return splitLength;
}
else
{
return maxLength - startIndex;
}
}
}
}
}