I would like to know how to get a file from a Vaadin Upload Component. Here is the example on the Vaadin Website
but it does not include how to save it other than something about OutputStreams.
Help!
To receive a file upload in Vaadin, you must implement Receiver interface, wich provides you with a receiveUpload(filename, mimeType)method, used to receive the info. The simplest code to do this would be (Taken as example from Vaadin 7 docs):
class FileUploader implements Receiver {
private File file;
private String BASE_PATH="C:\\";
public OutputStream receiveUpload(String filename,
String mimeType) {
// Create upload stream
FileOutputStream fos = null; // Stream to write to
try {
// Open the file for writing.
file = new File(BASE_PATH + filename);
fos = new FileOutputStream(file);
} catch (final java.io.FileNotFoundException e) {
new Notification("Could not open file<br/>",
e.getMessage(),
Notification.Type.ERROR_MESSAGE)
.show(Page.getCurrent());
return null;
}
return fos; // Return the output stream to write to
}
};
With that, the Uploader will write you a file in C:\. If you wish to something after the upload has completed successfully, or not, you can implement SucceeddedListener or FailedListener. Taking the example above, the result (with a SucceededListener) could be:
class FileUploader implements Receiver {
//receiveUpload implementation
public void uploadSucceeded(SucceededEvent event) {
//Do some cool stuff here with the file
}
}
Related
using java 8, tomcat 8
Hi, i am loading a file using properties, but i have a check before loading which returns the same properties object if its already been loaded (not null). which is a normal case scenario but i want to know if there is any way that if any change occur in target file, and some trigger should be called and refreshes all the properties objects. here is my code.
public static String loadConnectionFile(String keyname) {
String message = "";
getMessageFromConnectionFile();
if (propertiesForConnection.containsKey(keyname))
message = propertiesForConnection.getProperty(keyname);
return message;
}
public static synchronized void getMessageFromConnectionFile() {
if (propertiesForConnection == null) {
FileInputStream fileInput = null;
try {
File file = new File(Constants.GET_CONNECTION_FILE_PATH);
fileInput = new FileInputStream(file);
Reader reader = new InputStreamReader(fileInput, "UTF-8");
propertiesForConnection = new Properties();
propertiesForConnection.load(reader);
} catch (Exception e) {
Utilities.printErrorLog(Utilities.convertStackTraceToString(e), logger);
} finally {
try {
fileInput.close();
} catch (Exception e) {
Utilities.printErrorLog(Utilities.convertStackTraceToString(e), logger);
}
}
}
}
the loadConnectionFile method executes first and calls getMessageFromConnectionFile which has check implemented for "null", now if we remove that check it will definitely load updated file every time but it will slower the performance. i want an alternate way.
hope i explained my question.
thanks in advance.
Java has a file watcher service. It is an API. You can "listen" for changes in files and directories. So you can listen for changes to your properties file, or the directory in which your properties file is located. The Java Tutorials on Oracle's OTN Web site has a section on the watcher service.
Good Luck,
Avi.
I've been trying to save a JSON (currently, it's simply a generic file) to my device's internal storage. I've looked at tons of examples that look exactly like what I've written, but I can never find the file on my device.
Code to save file
public void saveJSONStringToFile(String json) {
FileOutputStream outfile = null;
String filename = "json_test.json";
try {
outfile = openFileOutput(filename, this.MODE_PRIVATE);
outfile.write(json.getBytes());
outfile.close();
} catch (Exception e) {
e.printStackTrace();
}
}
I know that it's not working because I've also implemented code to retrieve that file and the app just hangs when I try that, implying that it's looking for something that isn't there.
I am working in a old project.The project is in Spring MVC .In the project I have to generate a pdf file from a jsp page and store in a location and download that file. For that I am using wkhtmltopdf tool to convert the one specific jsp page into pdf format. Using wkhtmltopdf sometime works fine, it generate the pdf in specific location, but sometime it require more time. Also when I am trying to download the file from specific location , sometime it download a 0KB size file or sometime the downloaded file can't be open (with some size) but sometime download perfectly. If I check the file at define location, it exist and open normally.
Here is my code in controller class.
#RequestMapping(value="/dwn.htm",method=RequestMethod.GET)
public void dwAppFm(HttpSession session,HttpServletRequest request,HttpServletResponse response,#RequestParam String id) throws IOException,InterruptedException
{
final int BUFFER_SIZES=4096;
ServletContext context=request.getServletContext();
String savePath="/tmp/";//PDF file Generate Path
String fileName="PDFFileName"; //Pdf file name
FileInputStream inputStream=null;
BufferedInputStream bufferedInputStream=null;
OutputStream outputStream=null;
printApp(id,fileName);
Thread.sleep(1000);
printApp(id,fileName);
File download=new File(savePath+fileName+".pdf");
while(!download.canRead())
{
Thread.sleep(1000);
printApp(id,fileName);
download=new File(savePath+fileName+".pdf");
}
if(download.canRead()){//if the file can read
try{
Thread.sleep(1000);
inputStream=new FileInputStream(download);
bufferedInputStream=new BufferedInputStream(inputStream);
String mimeType = context.getMimeType(savePath+fileName+".pdf");
if (mimeType == null) {
mimeType = "application/octet-stream";
}
System.out.println("MIME type: " + mimeType);
response.setContentType(mimeType);
response.setContentLength((int)download.length());
String headerKey="Content-Disposition";
String headerValue=String.format("attachment;filename=\"%s\"", download.getName());
response.setHeader(headerKey, headerValue);
outputStream=response.getOutputStream();
byte[] buffer=new byte[BUFFER_SIZES];
int bytesRead=-1;
while ((bytesRead = bufferedInputStream.read(buffer)) != -1) {
outputStream.write(buffer, 0, bytesRead);
}
}catch(Exception e)
{
e.printStackTrace();
}
finally
{
try{
if(inputStream!=null)inputStream.close();
if(bufferedInputStream!=null)bufferedInputStream.close();
if(outputStream!=null)outputStream.close();
}
catch(Exception e)
{
e.printStackTrace();
}
}
}
}
public void printApp(String id,String fileName)
{
try{
String urlPath="http://localhost:8080/proj";
urlPath+="/genApp.htm?id="+id;//generate url to execute wkhtmltopdf
String wxpath="/home/exm/wkhtmltopdf";//the path where wkhtmltopdf located
String save="/tmp/"+fileName+".pdf";//File save Pathname
Process process=null;
process=Runtime.getRuntime().exec(wxpath+" "+urlPath+" "+save);
}catch(Exception e)
{}
}
#RequestMapping(value="/genApp.htm",method=RequestMethod.GET)
public String getApplicationPDF(HttpServletRequest request,HttpSession session,#RequestParam String id)
{
UDets uDets=uService.getAllById(Long.parseLong(id));//Methods to get details
request.setAttribute("uDets",uDets );
return "makeApp";//Name of the jsp page
}
In my code I have use Thread.sleep(1000) and printApp(id,fileName) method three times , since sometime wkhtmltopdf fail to generate pdf in certain time and then probability of downloading 0KB file is more. I haven't share the jsp page since the jsp page contain simple jsp page code of lots of line (the size of the generated pdf file is two page).
So the problem is what should I change in my code so that the pdf file generated and download without a failure also in heavy load in server.
If there is any best procedure or idea please share.
I don't like to use itext, since the jsp page contain complex design. Any advise is also appreciable and also thanks in advance.
I would say that your code is flawed not just a little but big time. You are checking if a file can be read, if not you start again a proces writing to the same file (at least twice). At some time you will endup with multiple processes trying to write to the same file, resulting in strange behavior.
I would refactor the printApp method to return the Process it created. Then call waitFor on that process. If it returns 0 and doesn't get interrupted it completed successfully and you should be able to download the file.
#RequestMapping(value="/dwn.htm",method=RequestMethod.GET)
public void dwAppFm(HttpSession session,HttpServletRequest request,HttpServletResponse response,#RequestParam String id) throws IOException,InterruptedException
{
String savePath="/tmp/";//PDF file Generate Path
String fileName="PDFFileName.pdf"; //Pdf file name
File download = new File(savePath, fileName);
try {
Process process = printApp(id, download.getPath());
int status = process.waitFor();
if (status == 0) {
response.setContentType("application/pdf");
response.setContentLength((int)download.length());
String headerKey="Content-Disposition";
String headerValue=String.format("attachment;filename=\"%s\"", download.getName());
StreamUtils.copy(new FileInputStream(download), response.getOutputStream())
} else {
// do something if it fails.
}
} catch (IOException ioe) {
// Do something to handle exception
} catch (InterruptedException ie) {
// Do something to handle exception
}
}
}
public Process printApp(String id, String pdf) throws IOException {
String urlPath="http://localhost:8080/proj";
urlPath+="/genApp.htm?id="+id;//generate url to execute wkhtmltopdf
String wxpath="/home/exm/wkhtmltopdf";//the path where wkhtmltopdf located
String command = wxpath+" "+urlPath+" "+pdf;
return Runtime.getRuntime().exec(command);
}
Something like the code above should to the trick.
In my Android app I'm downloading Video file using Quickblox API, on successful download I'm getting file content in the form of InputStream object now, using that InputStream object I wants to create android supported Video file and stored it on to the SDCard but I don't know how to create Video file using InputStream object. Please see the following code where I'm getting InputStream object.
QBContent.downloadFileTask(fileId, new QBEntityCallbackImpl<InputStream>()
{
#Override
public void onSuccess(InputStream inputStreamObject, Bundle params)
{
// TODO Auto-generated method stub
super.onSuccess(inputStreamObject, params);
});
}
Please help. Thank you..!
If the inputStreamObject is the content of an mp4 file, you could simply save the input stream to a file. That's your mp4 .
public static final String PREFIX = "myMusicfile";
public static final String SUFFIX = ".mp4";
public static File stream2file (InputStream in) throws IOException {
final File tempFile = File.createTempFile(PREFIX, SUFFIX);
tempFile.deleteOnExit();
try (FileOutputStream out = new FileOutputStream(tempFile)) {
IOUtils.copy(in, out);
}
return tempFile;
}
Hope it help :)
Thanks
I'm struggling with getting file upload/download to work properly in Play framework 2.2.2. I have a Student class with a field called "cv". It's annotated with #Lob, like this:
#Lob
public byte[] cv;
Here are the upload and download methods:
public static Result upload() {
MultipartFormData body = request().body().asMultipartFormData();
FilePart cv = body.getFile("cv");
if (cv != null) {
filenameCV = cv.getFilename();
String contentType = cv.getContentType();
File file = cv.getFile();
Http.Session session = Http.Context.current().session();
String studentNr = session.get("user");
Student student = Student.find.where().eq("studentNumber", studentNr).findUnique();
InputStream is;
try {
is = new FileInputStream(file);
student.cv = IOUtils.toByteArray(is);
} catch (IOException e) {
Logger.debug("Error converting file");
}
student.save();
flash("ok", "Vellykket! Filen " + filenameCV + " ble lastet opp til din profil");
return redirect(routes.Profile.profile());
} else {
flash("error", "Mangler fil");
return redirect(routes.Profile.profile());
}
}
public static Result download() {
Http.Session session = Http.Context.current().session();
Student student = Student.find.where().eq("studentNumber", session.get("user")).findUnique();
File f = new File("/tmp/" +filenameCV);
FileOutputStream fos;
try {
fos = new FileOutputStream(f);
fos.write(student.cv);
fos.flush();
fos.close();
} catch(IOException e) {
}
return ok(f);
}
The file seems to be correctly saved to the database (the cv field is populated with data, but it's obviously cryptic to me so I don't know for sure that the content is what it's supposed to be)
When I go to my website and click the "Download CV" link (which runs the download action), the file gets downloaded but can't be opened - saying the PDF viewer can't recognize the file etc. (Files uploaded have to be PDF)
Any ideas on what might be wrong?
Don't keep your files in DB, filesystem is much better for that! Save uploaded file on the disk with some unique name, then in your database keep only path to the file as a String!
It's cheaper in longer run (as said many times)
It's easier to handle downloads, i.e. in Play all you need to serve PDF is:
public static Result download() {
File file = new File("/full/path/to/your.pdf");
return ok(file);
}
it will set proper headers, like Content-Disposition, Content-Length and Content-Type not only for PDFs