避免在服務器上傳文件時出現重複現象

我想在上傳文件時避免重複。如果一個文件被更新了，然後儘管它與之前上傳的文件名稱相同，我應該可以在服務器上上傳文件。避免在服務器上傳文件時出現重複現象

我已經寫了下列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()); 
      }}

不過，我收到相同的最後修改日期和時間這兩個文件。並且如果上傳了新文件storeFile.lastModified（）將返回星期四01 01 05:30:00 IST 1970值

來源

2016-09-26 Radhika Kulkarni

哦，諷刺....（關於避免重複的問題是重複的） –

更新的文件不應該歸類爲重複 –

您能否確認OS Explorer已上傳的文件的實際上次修改日期是什麼？

在SimpleDateFormat的構造ARG米

第二件事代表分鐘，M代表month.Also S代表millsecond.So您正確的代碼將的SimpleDateFormat（「YYYY-MM-DD HH：MM：S」）

你可以嘗試這些更改並檢查嗎？

來源

2016-09-26 04:13:59 gero

它不工作的S ..實際修改日期是2016/25/09 10:46： 009 –

避免在服務器上傳文件時出現重複現象

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