如何使用Java上傳文件？

Question

您好，我試圖使用Java文件上傳文件。但是我沒有得到它。我得到的文件大小為0，我在這里提供我的Java代碼。 告訴我為什么我不能上傳到特定的文件夾。 我想將我的文件存儲在特定的文件夾中。 我正在嘗試獲取文件大小，文件名，但我在錯誤的地方輸入了空值，請告訴我。

public void updateTesti(ActionRequest actionRequest,ActionResponse actionResponse) throws IOException, PortletException
{
    //image upload logic
    String folder_for_upload =(getPortletContext().getRealPath("/"));
    //String folder=actionRequest.getParameter("uploadfolder");
    realPath=getPortletContext().getRealPath("/");  

    logger.info("RealPath is" + realPath);
    logger.info("Folder is :" + folder_for_upload);
    try
    {
        logger.info("Admin is try to upload");

        UploadPortletRequest uploadRequest = PortalUtil.getUploadPortletRequest(actionRequest);

        if (uploadRequest.getSize("fileName") == 0) {
            SessionErrors.add(actionRequest, "error");
        }
        String sourceFileName = uploadRequest.getFileName("fileName");
        File uploadedFile = uploadRequest.getFile("fileName");
        System.out.println("Size of uploaded file: " + uploadRequest.getSize("fileName"));

        logger.info("Uploded file name is: " + uploadRequest.getFileName("fileName"));                  
        String destiFolder=("/home/ubuntu/liferay/liferay-portal-6.1.1-ce-ga2/tomcat-7.0.27/webapps/imageUpload-portlet/image");
        String newsourcefilename = (uploadRequest.getFileName("fileName"));
        File  newFile = new File(destiFolder +"/"+ newsourcefilename);

        logger.info("New file name: " + newFile.getName());
        logger.info("New file path: " + newFile.getPath());

        InputStream in = new BufferedInputStream(uploadRequest.getFileAsStream("fileName"));

        FileInputStream fis = new FileInputStream(uploadedFile);
        FileOutputStream fos = new FileOutputStream(newFile);
        byte[] bytes_ = FileUtil.getBytes(in);
        int i = fis.read(bytes_);
        while (i != -1) {
            fos.write(bytes_, 0, i);
            i = fis.read(bytes_);
        }
        fis.close();
        fos.close();
        Float size = (float) newFile.length();

        System.out.println("file size bytes:" + size);
        System.out.println("file size Mb:" + size / 1048576);

        logger.info("File created: " + newFile.getName());
        SessionMessages.add(actionRequest, "success");

    }
    catch (FileNotFoundException e)
    {
        System.out.println("File Not Found.");
        e.printStackTrace();
        SessionMessages.add(actionRequest, "error");
    }
    catch (NullPointerException e)
    {
        System.out.println("File Not Found");
        e.printStackTrace();
        SessionMessages.add(actionRequest, "error");
    }
    catch (IOException e1)
    {
        System.out.println("Error Reading The File.");
        SessionMessages.add(actionRequest, "error");
        e1.printStackTrace();
    }
}

Answer 1

您需要執行此操作以上傳小於1kb的小文件

File f2 = uploadRequest.getFile("fileupload", true);

它們僅存儲在內存中。 如果我得到一個空指針，或者在我的原始文件（f1.length）== 0的情況下，我在catch語句中有它

Answer 2

我已經執行了您的代碼。它按預期運行。您的jsp頁面可能有問題。我不確定，但是可能是您的name屬性與您在processAction中使用的屬性不同（假設您在使用portlet）。參數區分大小寫，因此請再次檢查。

您將在下面的鏈接中找到更多信息。文件上傳中有很好的解釋。

http://www.codeyouneed.com/liferay-portlet-file-upload-tutorial/

Answer 3

我檢查了一個文件上傳代碼，當我在本地系統中實現該代碼時，portlet將我上傳的文件保存在tomcat/webbapp/abc_portlet_project位置中，我不了解的是在哪里找到了portlet

字符串文件夾= getInitParameter（“ uploadFolder”）;

  String realPath = getPortletContext().getRealPath("/"); System.out.println("RealPath" + realPath +"\\\\" + folder); try { 

UploadPortletRequest uploadRequest = PortalUtil.getUploadPortletRequest（actionRequest）; System.out.println（“ Size：” + uploadRequest.getSize（“ fileName”）））;

如果（uploadRequest.getSize（“ fileName”）== 0）{SessionErrors.add（actionRequest，“ error”）;}

字符串sourceFileName = uploadRequest.getFileName（“ fileName”）; 文件file = uploadRequest.getFile（“ fileName”）;

System.out.println（“ Nome file：” + uploadRequest.getFileName（“ fileName”））; 文件newFolder = null; newFolder =新文件（realPath +“ \\” +文件夾）； if（！newFolder.exists（））{newFolder.mkdir（）; }文件newfile = null; newfile =新文件（newFolder.getAbsoluteFile（）+“ \\” + sourceFileName）; System.out.println（“新文件名：” + newfile.getName（））; System.out.println（“新文件路徑：” + newfile.getPath（））;

InputStream in = new BufferedInputStream（uploadRequest.getFileAsStream（“ fileName”））; FileInputStream fis =新的FileInputStream（file）; FileOutputStream fos = new FileOutputStream（newfile）;