primefaces p:graphicImage 流的用法

File f = new File("e:/1456199126737.jpg");
            BufferedImage bufferedImg = ImageIO.read(f);
            ByteArrayOutputStream os = new ByteArrayOutputStream();
            ImageIO.write(bufferedImg, "jpeg", os);
           StreamedContent image= new DefaultStreamedContent(new ByteArrayInputStream(os.toByteArray()), "image/jpeg");