Configuração no Ireport

\tomcat\webapps\seuProjeto\reports

String nomeJasper = new String("");
	nomeJasper="relatorio.jasper";

    	ServletOutputStream servletOutputStream = res.getOutputStream();
        	
    	File reportFileJasper = new File(getServletConfig().getServletContext() .getRealPath("/reports/"+nomeJasper));
        byte[] bytes = null;

        try {
        	bytes = JasperRunManager.runReportToPdf(reportFileJasper.getPath(), parametros, con);
        	
        	res.setContentType("application/pdf");
        	res.setContentLength(bytes.length);
        	
        	servletOutputStream.write(bytes, 0, bytes.length);
        	servletOutputStream.flush();
        	servletOutputStream.close();
        } catch (JRException e) {
        	StringWriter stringWriter = new StringWriter();
        	PrintWriter printWriter = new PrintWriter(stringWriter);
        	e.printStackTrace(printWriter);
        	res.setContentType("text/plain");
        	res.getOutputStream().print(stringWriter.toString());
        };