問題描述

我想限制可以上傳到應用程序的文件大小.為了實現這一點，我想在上傳的文件大小超過限制時從服務器端中止上傳過程.

I'd like to limit the size of the file that can be uploaded to an application. To achieve this, I'd like to abort the upload process from the server side when the size of the file being uploaded exceeds a limit.

有沒有辦法在不等待 HTTP 請求完成的情況下從服務器端中止上傳過程?

Is there a way to abort an upload process from the server side without waiting the HTTP request to finish?

推薦答案

你可以這樣做(使用 Commons 庫):

You can do something like this (using the Commons library):

    public class UploadFileServiceImpl extends HttpServlet
    {
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException
        {
            response.setContentType("text/plain");

            try
            {
                FileItem uploadItem = getFileItem(request);
                if (uploadItem == null)
                {
                        // ERROR
                }   

                // Add logic here
            }
            catch (Exception ex)
            {
                response.getWriter().write("Error: file upload failure: " + ex.getMessage());           
            }
        }

        private FileItem getFileItem(HttpServletRequest request) throws FileUploadException
        {
            DiskFileItemFactory factory = new DiskFileItemFactory();        

             // Add here your own limit         
             factory.setSizeThreshold(DiskFileItemFactory.DEFAULT_SIZE_THRESHOLD);

         ServletFileUpload upload = new ServletFileUpload(factory);

             // Add here your own limit
             upload.setSizeMax(DiskFileItemFactory.DEFAULT_SIZE_THRESHOLD);


            List<?> items = upload.parseRequest(request);
            Iterator<?> it = items.iterator();
            while (it.hasNext())
            {
                FileItem item = (FileItem) it.next();
                        // Search here for file item
                if (!item.isFormField() && 
                  // Check field name to get to file item  ... 
                {
                    return item;
                }
            }

            return null;
        }
    }

這篇關于中止從 servlet 上傳以限制文件大小的文章就介紹到這了，希望我們推薦的答案對大家有所幫助，也希望大家多多支持html5模板網！