how to deal with exceptions on a Spring controller while generating a file

Question

I've implemented a Spring controller that generates a PDF file, consuming my service layer. The problem is that when some exception is thrown during the execution of the method, even if I get the exception with a try-catch block, spring tries to resolve the view based on the current URL.

I honestly have no idea on what is causing this behavior.

    @RequestMapping("/cliente")
    public void relatorioCliente(EdicaoMovimentacaoWrapper wrapper, @AuthenticationPrincipal Usuario usuario) {
        try {
            gerarReportService.relatorioParaCliente(wrapper.getContaId(), usuario);

        } catch (Exception e) {
            e.printStackTrace();
            // TODO alguma coisa
        }
    }

the relatorioParaCliente method generates the PDF and exports it to the response's OutputStream.

Expected: the exception gets caught, the stack trace gets printed and nothing happens to the user. Actual result: Spring redirects the user to views/cliente.jsp

UPDATE

I've tried changing the return type of the method so it looks like this now:

    @RequestMapping("/cliente")
    public ModelAndView relatorioCliente(EdicaoCadastroMovimentacaoWrapper wrapper, @AuthenticationPrincipal Usuario usuario) {
        try {
            gerarReportService.relatorioParaCliente(wrapper.getContaId(), usuario);

        } catch (Exception e) {
            e.printStackTrace();
            return new ModelAndView("/contas/" + wrapper.getContaId());
        }
        return null;
    }

But this has no effect on my code. I suppose that this does not affect the code because the outputStream gets used on the service. take a look:

@Service
public class ExportarReportPdfService {

    @Autowired
    private HttpServletResponse res;

    public void exportar(List<JasperPrint> jasperPrintList) throws IOException {

        JRPdfExporter exporter = new JRPdfExporter();

        exporter.setExporterInput(SimpleExporterInput.getInstance(jasperPrintList));

        exporter.setExporterOutput(new SimpleOutputStreamExporterOutput(res.getOutputStream()));

        SimplePdfExporterConfiguration configuration = new SimplePdfExporterConfiguration();

        configuration.setCreatingBatchModeBookmarks(true);

        exporter.setConfiguration(configuration);

        res.setContentType("application/x-pdf");
        res.setHeader("Content-disposition", "inline; filename=relatorio.pdf" );


        try {
            exporter.exportReport();
        } catch (Exception e) {
            e.printStackTrace();
            throw new CriacaoReportException("Erro ao exportar para PDF");
        } finally {
            OutputStream out = res.getOutputStream();
            out.flush();
            out.close();

        }
    }

Answer 1

Here is what I did to solve the problem:

instead of Autowiring the response on the service and exporting the pdf from there, I generate a byteArray and return it to the controller:

@Service
public class ExportarReportPdfService {

    public byte[] exportar(List<JasperPrint> jasperPrintList)  {

        final ByteArrayOutputStream outputStream = new ByteArrayOutputStream();

        JRPdfExporter exporter = new JRPdfExporter();

        exporter.setExporterInput(SimpleExporterInput.getInstance(jasperPrintList));

        exporter.setExporterOutput(new SimpleOutputStreamExporterOutput(outputStream));

        [OMITED CODE]

        try {
            exporter.exportReport();
            return outputStream.toByteArray();
        } catch (Exception e) {
            e.printStackTrace();
            throw new CriacaoReportException("Erro ao exportar para PDF");
        }
    }
}

And the controller sends the response as a ResponseEntity :

        @RequestMapping("/geral")
        public ResponseEntity<InputStreamResource> relatorioAdministrador(EdicaoCadastroMovimentacaoWrapper wrapper, @AuthenticationPrincipal Usuario usuario) {

            byte[] arquivo = gerarReportService.relatorioParaAdmin(wrapper.getContaId(), usuario);

            return ResponseEntity
                    .ok()
                    .contentLength(arquivo.length)
                    .contentType(MediaType.parseMediaType("application/pdf"))
                    .header("Content-Disposition", "attachment; filename=relatorio.pdf")
                    .body(new InputStreamResource(new ByteArrayInputStream(arquivo)));
        }

So if any exception occurs it will be caught in the ExceptionHandler as @cmoetzing explained in the comments:

    @ExceptionHandler(CriacaoReportException.class)
    public ModelAndView trataGeracaoRelatorio(CriacaoReportException exception) {
        return new ModelAndView("redirect:/");
    }