Исключение Null pointer jnlp.FileSaveService

Question

Я пытаюсь использовать файл jnlp.FileSaveService для файла. Save файла aslook, сгенерированного в contoroller java-приложения. Я нашел пример здесь http://docs.oracle.com/javase/tutorial/deployment/doingMoreWithRIA/usingJNLPAPI.html Я не совсем понимаю, как это работает, и я получаю пустое исключение poniter на этой линии:

fc = fss.saveFileDialog(null, null, new ByteArrayInputStream(txt.getBytes()), null); 

Могу ли я что-то неправильно передавая методу SaveFileDialog или что-то еще? Буду признателен за любую помощь.

static private FileOpenService fos = null; 
static private FileSaveService fss = null; 
static private FileContents fc = null; 

private static synchronized void initialize() { 
    try { 
     fos = (FileOpenService)ServiceManager.lookup("javax.jnlp.FileOpenService"); 
     fss = (FileSaveService)ServiceManager.lookup("javax.jnlp.FileSaveService"); 
    } catch (UnavailableServiceException e) { 
    } 
} 

public static void save(String txt) { 
    initialize(); 
    try { 
     // Show save dialog if no name is already given 
     if (fc == null) { 
      fc = fss.saveFileDialog(null, null, new ByteArrayInputStream(txt.getBytes()), null); 
      // file saved, done 
      return; 
     } 
     // use this only when filename is known 
     if (fc != null) { 
      writeToFile(txt, fc); 
     } 
    } catch (IOException ioe) {ioe.printStackTrace(System.out); 
    } 
} 

public static void saveAs(String txt) { 
    initialize(); 
    try { 
     if (fc == null) { 
      // If not already saved. Save-as is like save 
      save(txt); 
     } else { 
      fc = fss.saveAsFileDialog(null, null, fc); 
      save(txt); 
     } 
    } catch (IOException ioe) { 
     ioe.printStackTrace(System.out); 
    } 
} 

private static void writeToFile(String txt, FileContents fc) throws IOException { 
    int sizeNeeded = txt.length() * 2; 
    if (sizeNeeded > fc.getMaxLength()) { 
     fc.setMaxLength(sizeNeeded); 
    } 
    BufferedWriter os = new BufferedWriter(new OutputStreamWriter(fc.getOutputStream(true))); 
    os.write(txt); 
    os.close(); 
} 

@RequestMapping(value = "/exportPhonebook.html", method = RequestMethod.POST) 
public String exportPhonebook(Model model) { 

    List<User> listOfAllUsers = phoneBookSer.fetchAllUsers(); 
    String phonebook = ""; 

    for (User user : listOfAllUsers) { 
     phonebook = phonebook + user.getSurname() + " " + user.getName() + 
     ", Phone Number: " + user.getPhoneNumber() + ";\r\n" ; 
    } 

    saveAs(phonebook); 
} 

Вот StackTrace

20.03.2013. 13:19:41 org.apache.catalina.core.StandardWrapperValve invoke 
SEVERE: Servlet.service() for servlet [springDipatcher] in context with path [/phonebook] threw exception [Request processing failed; nested exception is  java.lang.NullPointerException] with root cause 
java.lang.NullPointerException 
at phonebook.controllers.ExportPhonebook.save(ExportPhonebook.java:80) 
at phonebook.controllers.ExportPhonebook.saveAs(ExportPhonebook.java:97) 
at phonebook.controllers.ExportPhonebook.exportPhonebook(ExportPhonebook.java:129) 
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) 
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) 
at java.lang.reflect.Method.invoke(Unknown Source) 
at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.invokeHandlerMethod(HandlerMethodInvoker.java:176) 
at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.invokeHandlerMethod(AnnotationMethodHandlerAdapter.java:436) 
at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.handle(AnnotationMethodHandlerAdapter.java:424) 
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:790) 
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:719) 
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:644) 
at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:560) 
at javax.servlet.http.HttpServlet.service(HttpServlet.java:641) 
at javax.servlet.http.HttpServlet.service(HttpServlet.java:722) 
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:304) 
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) 
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:328) 
at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:116) 
at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:83) 
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:340) 
at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:95) 
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:340) 
at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:100) 
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:340) 
at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:79) 
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:340) 
at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:54) 
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:340) 
at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:35) 
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:340) 
at org.springframework.security.web.authentication.www.BasicAuthenticationFilter.doFilter(BasicAuthenticationFilter.java:119) 
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:340) 
at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:187) 
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:340) 
at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:105) 
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:340) 
at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:80) 
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:340) 
at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:175) 
at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:237) 
at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:167) 
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243) 
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) 
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88) 
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76) 
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243) 
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) 
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:240) 
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:164) 
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:498) 
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:164) 
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100) 
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:562) 
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118) 
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:394) 
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:243) 
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:188) 
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:302) 
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source) 
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) 
at java.lang.Thread.run(Unknown Source) 

Answer 1

я взял другой подход, чтобы решить мою проблему. Я использовал content-disposition, чтобы сохранить .txt файл создан в Controller. Вы можете увидеть мой код ниже.

private void setResponseHeaderTXT(HttpServletResponse response) { 
    response.setContentType("text/plain; charset=UTF-8"); 
    response.setHeader("content-disposition", "attachment; filename=imenik.txt"); 
} 
@RequestMapping(value = "/exportPhonebook.html", method = RequestMethod.POST) 
public void exportPhonebook(Model model, HttpServletResponse response) { 

    List<User> listOfAllUsers = phoneBookSer.fetchAllUsers(); 
    String phonebook = ""; 

    for (User user : listOfAllUsers) { 
     phonebook = phonebook + user.getSurname() + " " + user.getName() + ", + 
     ", Phone number: " + user.getPhoneNumber() + ";\r\n" ; 
    } 

    try { 
     setResponseHeaderTXT(response); 
     OutputStream outputStream = response.getOutputStream(); 
     outputStream.write(phonebook.getBytes(Charset.forName("UTF-8"))); 
     outputStream.flush(); 
     outputStream.close(); 
    } catch (IOException e) { 
     e.printStackTrace(); 
    } 
} 

Я делал нечто подобное с экспортом моей телефонной книги в формате PDF использованием IText.

private void setResponseHeaderPDF(HttpServletResponse response) { 
    response.setContentType("application/pdf"); 
    response.setHeader("content-disposition", "attachment; filename=imenik.pdf"); 
} 

@RequestMapping(value = "/exportPhonebook.html", method = RequestMethod.POST) 
public void exportPhonebook(Model model, @RequestParam("buttonSpremiImenik") String buttonSpremiImenik, HttpServletResponse response, HttpServletRequest request) { 

    try { 
     setResponseHeaderPDF(response); 
     Document document = new Document(); 
     ByteArrayOutputStream baosPDF = new ByteArrayOutputStream(); 
     PdfWriter pdfWriter = null; 
     pdfWriter = PdfWriter.getInstance(document, baosPDF); 
     document.open(); 
     addMetaData(document); 
     addTitlePage(document); 
     addContent(document); 
     document.close(); 
     pdfWriter.close(); 
     OutputStream os = response.getOutputStream(); 
     baosPDF.writeTo(os); 
     os.flush(); 
     os.close(); 
    } catch (Exception e) { 
     e.printStackTrace(); 
    } 
} 

private static Font catFont = new Font(Font.FontFamily.TIMES_ROMAN, 18,Font.BOLD); 
private static Font smallBold = new Font(Font.FontFamily.TIMES_ROMAN, 12,Font.BOLD); 
private static Font tableHeaderFont = new Font(Font.FontFamily.TIMES_ROMAN, 10,Font.BOLD); 
public static String[][] FONTS = {{"c:/windows/fonts/arial.ttf", BaseFont.IDENTITY_H}}; 


private static void addMetaData(Document document) { 
    document.addTitle("Phonebook"); 
    document.addSubject("phonebook"); 
    document.addKeywords("phonebook"); 
    document.addAuthor("John Smith"); 
    document.addCreator("John Smith"); 
} 
private static void addTitlePage(Document document) throws DocumentException { 
    Paragraph preface = new Paragraph(); 
    addEmptyLine(preface, 1); 
    preface.add(new Paragraph("Phonebook", catFont)); 
    addEmptyLine(preface, 1); 
    preface.add(new Paragraph("Generated: " + new Date(), smallBold)); 
    addEmptyLine(preface, 1); 
    document.add(preface); 
} 

private void addContent(Document document) throws DocumentException { 

    Paragraph paragraph = new Paragraph(); 
    addEmptyLine(paragraph, 1); 

    // Add a table 
    createTable(paragraph); 

    // Now add all this to the document 
    document.add(paragraph); 
} 


private static void addEmptyLine(Paragraph paragraph, int number) { 
    for (int i = 0; i < number; i++) { 
     paragraph.add(new Paragraph(" ")); 
    } 
} 
private void createTable(Paragraph paragraf) throws DocumentException { 

    PdfPTable table = new PdfPTable(9); 
    table.setTotalWidth(new float[]{ 58, 50, 95, 60, 60, 135, 60, 42, 30 }); 
    table.setLockedWidth(true); 

    List<User> listOfAllUsers = phoneBookSer.fetchAllUsers(); 

    PdfPCell c1 = new PdfPCell(new Phrase("Prezime", tableHeaderFont)); 
    c1.setHorizontalAlignment(Element.ALIGN_CENTER); 
    table.addCell(c1); 

    c1 = new PdfPCell(new Phrase("Ime", tableHeaderFont)); 
    c1.setHorizontalAlignment(Element.ALIGN_CENTER); 
    table.addCell(c1); 

    c1 = new PdfPCell(new Phrase("Organizacijska jedinica", tableHeaderFont)); 
    c1.setHorizontalAlignment(Element.ALIGN_CENTER); 
    table.addCell(c1); 

    c1 = new PdfPCell(new Phrase("Telefon", tableHeaderFont)); 
    c1.setHorizontalAlignment(Element.ALIGN_CENTER); 
    table.addCell(c1); 

    c1 = new PdfPCell(new Phrase("Telefaks", tableHeaderFont)); 
    c1.setHorizontalAlignment(Element.ALIGN_CENTER); 
    table.addCell(c1); 

    c1 = new PdfPCell(new Phrase("E-mail", tableHeaderFont)); 
    c1.setHorizontalAlignment(Element.ALIGN_CENTER); 
    table.addCell(c1); 

    c1 = new PdfPCell(new Phrase("Lokacija", tableHeaderFont)); 
    c1.setHorizontalAlignment(Element.ALIGN_CENTER); 
    table.addCell(c1); 

    c1 = new PdfPCell(new Phrase("Kat", tableHeaderFont)); 
    c1.setHorizontalAlignment(Element.ALIGN_CENTER); 
    table.addCell(c1); 

    c1 = new PdfPCell(new Phrase("Soba", tableHeaderFont)); 
    c1.setHorizontalAlignment(Element.ALIGN_CENTER); 
    table.addCell(c1); 

    table.setHeaderRows(1); 


    BaseFont bf = null; 
    try { 
     bf = BaseFont.createFont(FONTS[0][0], FONTS[0][1], BaseFont.EMBEDDED); 
    } catch (IOException e) { 
     e.printStackTrace(); 
    } 
    Font fontArial = new Font(bf, 9); 

    //Automatically detects fonts 
    //FontFactory.registerDirectories(); 
    //Font fontArial9 = FontFactory.getFont("Arial", 9); 

    for (User user : listOfAllUsers) { 
     PdfPCell cell1 = new PdfPCell(new Phrase(user.getPrezime(), fontArial)); 
     table.addCell(cell1); 
     PdfPCell cell2 = new PdfPCell(new Phrase(user.getIme(), fontArial)); 
     table.addCell(cell2); 
     PdfPCell cell3 = new PdfPCell(new Phrase(user.getOrganizacijskaJedinica(), fontArial)); 
     table.addCell(cell3); 
     PdfPCell cell4 = new PdfPCell(new Phrase(user.getTelefon(), fontArial)); 
     table.addCell(cell4); 
     PdfPCell cell5 = new PdfPCell(new Phrase(user.getTelefaks(), fontArial)); 
     table.addCell(cell5); 
     PdfPCell cell6 = new PdfPCell(new Phrase(user.getEmail(), fontArial)); 
     table.addCell(cell6); 
     PdfPCell cell7 = new PdfPCell(new Phrase(user.getLokacija(), fontArial)); 
     table.addCell(cell7); 
     PdfPCell cell8 = new PdfPCell(new Phrase(user.getKat(), fontArial)); 
     table.addCell(cell8); 
     PdfPCell cell9 = new PdfPCell(new Phrase(user.getBrojSobe(), fontArial)); 
     table.addCell(cell9); 
    } 

    paragraf.add(table); 
}