Question

我希望在上传文件时避免重复。如果文件已更新，那么虽然它与之前上传的文件具有相同的名称，但我应该能够在服务器上上传该文件。

我写了以下servlet：

protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        if (req.getParameter("from").equals("upload")) {

            // checks if the request actually contains upload file
            if (!ServletFileUpload.isMultipartContent(req)) {
                PrintWriter writer = resp.getWriter();
                writer.println("Request does not contain upload data");
                writer.flush();
                return;
            }

            // configures upload settings
            DiskFileItemFactory factory = new DiskFileItemFactory();

            factory.setRepository(new File(System.getProperty("java.io.tmpdir")));

            ServletFileUpload upload = new ServletFileUpload(factory);

            // constructs the directory path to store upload file
            String uploadPath = getServletContext().getRealPath("") + File.separator + UPLOAD_DIRECTORY;
            // creates the directory if it does not exist
            File uploadDir = new File(uploadPath);
            if (!uploadDir.exists()) {
                uploadDir.mkdir();
            }

            try {
                // parses the request's content to extract file data
                List formItems = upload.parseRequest(req);
                Iterator iter = formItems.iterator();

                // iterates over form's fields
                while (iter.hasNext()) {
                    FileItem item = (FileItem) iter.next();
                    // processes only fields that are not form fields
                    if (!item.isFormField()) {
                        String fileName = new File(item.getName()).getName();

                        filePath = uploadPath + File.separator + fileName;
                        File storeFile = new File(filePath);
                        SimpleDateFormat f = new SimpleDateFormat("yyyy-MM-dd HH:mm:sss");
                        System.out.println(f.format(storeFile.lastModified()));
                        System.out.println(storeFile.lastModified());
                        System.out.println(f.parse(f.format(storeFile.lastModified())));

                        File[] files = new File(
                                "C:\\bootcamp\\programs\\eclipse-jee-neon-RC3-win32-x86_64\\eclipse\\workspace\\.metadata\\.plugins\\org.eclipse.wst.server.core\\tmp0\\wtpwebapps\\excelFileManagement\\upload")
                                        .listFiles();
                        int uploadFiles=0;
                        for (File file : files) {


                                if (fileName.equals(file.getName())) {
                                    uploadFiles =1;
                                    System.out.println("same");
                                    DateFormat df = new SimpleDateFormat("yyyy-mm-dd hh:mm:sss");
                                    String currentFile = df.format(storeFile.lastModified());
                                    String storedFile = df.format(file.lastModified());
                                    System.out.println("currentFile" + currentFile + "storedFile" + storedFile);
                                    if (currentFile.contains(storedFile)) {
                                        System.out.println("Same file cannot be uploaded again");
                                        getServletContext().getRequestDispatcher("/Error.jsp").forward(req, resp);
                                    } else {
                                        // saves the file on disk
                                        item.write(storeFile);
                                        System.out.println("Upload has been done successfully!");
                                        // Reading excel file
                                        ReadingExcelFile rd = new ReadingExcelFile();
                                        rd.readExcel(filePath);
                                        getServletC

ontext().getRequestDispatcher("/DisplayTables.jsp").forward(req, resp);


                                    } 
                                }
}
catch (Exception ex) {
                System.out.println("There was an error: " + ex.getMessage());
            }}

但是，我对这两个文件的最后修改日期和时间都是相同的。如果上传了新文件，storeFile.lastModified（）将返回Thu Jan 01 05:30:00 IST 1970 value

Answer 1

您能否确认OS资源管理器已上传文件的实际lastModified日期是什么？

SimpleDateFormat构造函数中的第二件事arg m代表分钟而M代表月份。也就是S代表毫秒。所以你的正确代码将是 SimpleDateFormat（＆＃34; yyyy-MM-dd hh：mm：S＆＃34;）

您可以尝试这些更改并检查吗？

在服务器上传文件时避免重复

1 个答案: