ServletOutputStream 和图片的关系

Question

在前台页面有如下语句<img onclick="this.src='/ran/random?random='+Math.random()" alt="验证码，点击图片更换" src="/ran/random?random=0.2868249340216069" width="86" height="40"> 其中src 指向的地址不是一个img文件，而是一个转到SpringMVC的类中方法src="/ran/random?random=0.2868249340216069" 方法如下： @Controller public class RandomCodeController { @RequestMapping(value={"/ran/random"}) public void genericRandomCode(HttpServletRequest request, HttpServletResponse response) throws IOException { response.setHeader("Cache-Control", "private,no-cache,no-store"); response.setContentType("image/png"); HttpSession session = request.getSession(); int width = 85; int height = 28; BufferedImage image = new BufferedImage(width, height, 2); Graphics2D g = image.createGraphics(); g.setComposite(AlphaComposite.getInstance(3, 1.0f)); Random random = new Random(); g.setColor(new Color(231, 231, 231)); g.fillRect(0, 0, width, height); g.setFont(new Font("Microsoft YaHei", 2, 24)); String sRand = ""; for (int responseOutputStream = 0; responseOutputStream < 4; ++responseOutputStream) { String rand = String.valueOf(random.nextInt(10)); sRand = sRand + rand; g.setColor(new Color(121, 143, 96)); g.drawString(rand, 13 * responseOutputStream + 16, 23); } session.setAttribute("COMMON_RAND_CODE", (Object)sRand); g.dispose(); ServletOutputStream var12 = response.getOutputStream(); ImageIO.write((RenderedImage)image, "png", (OutputStream)var12); var12.close(); } } 所以其实这个src相联系的是一个ServletOutputStream这个地方我不太理解ServletOutputStream如何和一个图片联系起来？

Answer 1

不仅仅是图片，其他文件也是以流的形式传输的。浏览器把后台给的流解析成了图片了。