HTML5目录上载Java Servlet处理

Question

我在绕过HTML5 webkitdirectory递归目录上传：

<form action="http://localhost:8080/upload" method="post" enctype="multipart/form-data">
    <input type="file" name="file_input" webkitdirectory="" directory="">
    <input type="submit">
</form>

在服务器端，我使用apache-commons-fileupload 1.3.1 (Streaming API)处理它：

@WebServlet(urlPatterns = "/upload")
public class DirUploadServlet extends HttpServlet
{        
    @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
    {
        ServletFileUpload upload = new ServletFileUpload();

        response.setContentType(MediaType.TEXT_PLAIN);
        PrintWriter writer = response.getWriter();

        try
        {
            FileItemIterator iter = upload.getItemIterator(request);

            while (iter.hasNext())
            {
                FileItemStream item = iter.next();

                if (!item.isFormField())
                {
                    writer.println(item.getName());
                }
            }
        }
        catch (FileUploadException e)
        {
            throw new IOException(e);
        }
    }
}

这对于没有子目录的目录很有效。但是，如果我尝试选择一个包含子目录的目录，请求将被正确发送，但是在服务器端我得到以下异常：

org.apache.commons.fileupload.MultipartStream$MalformedStreamException: Stream ended unexpectedly
    at org.apache.commons.fileupload.MultipartStream$ItemInputStream.makeAvailable(MultipartStream.java:1005)
    at org.apache.commons.fileupload.MultipartStream$ItemInputStream.close(MultipartStream.java:943)
    at org.apache.commons.fileupload.MultipartStream$ItemInputStream.close(MultipartStream.java:922)
    at org.apache.commons.fileupload.FileUploadBase$FileItemIteratorImpl$FileItemStreamImpl.close(FileUploadBase.java:866)
    at org.apache.commons.fileupload.FileUploadBase$FileItemIteratorImpl.findNextItem(FileUploadBase.java:1017)
    at org.apache.commons.fileupload.FileUploadBase$FileItemIteratorImpl.hasNext(FileUploadBase.java:1106)
    at DirUploadServlet.doPost(DirUploadServlet.java:45)

这个请求(来自Ubuntu Chromium)对我来说似乎是合法的：

------WebKitFormBoundaryMQ53uSzX0G6oZpWL
Content-Disposition: form-data; name="file_input"; filename="probadir/dir2/."
Content-Type: application/octet-stream


------WebKitFormBoundaryMQ53uSzX0G6oZpWL
Content-Disposition: form-data; name="file_input"; filename="probadir/file1"
Content-Type: application/octet-stream


------WebKitFormBoundaryMQ53uSzX0G6oZpWL
Content-Disposition: form-data; name="file_input"; filename="probadir/dir2/file2"
Content-Type: application/octet-stream


------WebKitFormBoundaryMQ53uSzX0G6oZpWL--

该错误与Windows中的Google Chrome相同。IE和Firefox还没有这个功能。

Answer 1

这里的问题不在于commons-fileupload，而在于请求或servlet容器本身。当我使用Glassfish 3.1.2和Servlet API以二进制形式注销请求时，我收到以下代码：

------WebKitFormBoundary7AVw8qF0sdCpYB1P
Content-Disposition: form-data; name="files[]"; filename="probadir/dir2/."
Content-Type: application/octet-stream

\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\
\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\
\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\
\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\

等等，并且直到结束为止都是0字节。这就是为什么来自Servlet3的commons-fileupload API和Multipart API (例如request.getPart())都会抛出异常。

现在我认为唯一的解决方案不是使用标准的HTML表单提交，而是使用这里解释的JS单独提交文件：Keep Directory Structure When Uploading