java中项目实现一个随机输出图片功能

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java  实现输出随机图片实例代码

输出随机图片(CAPTCHA图像):Completely Automated Public Turing Test to Tell Computers and Humans Apart (全自动区分计算机和人类的测试)

相关主要类(jdk 查看api)

BufferedImage:内存图像
Graphics：画笔
Imageio：输出图像

放在html页面上<img src/>

注意：浏览器默认会缓存图片

   public static int WIDTH = 120; public static int HEIGHT = 25;  public void doGet(httpservletRequest request, HttpServletResponse response)     throws ServletException, IOException {    response.setContentType("text/html");   //创建内存图像   BufferedImage image = new BufferedImage(WIDTH,HEIGHT,BufferedImage.TYPE_INT_RGB);   //勾勒图像   Graphics graphics = image.getGraphics();   //设置背景   graphics.setColor(Color.WHITE);   graphics.fillRect(0, 0, WIDTH, HEIGHT);   //设置边框   graphics.setColor(Color.BLUE);   graphics.drawRect(1, 1, WIDTH-2, HEIGHT-2);   //画干扰线   graphics.setColor(Color.YELLOW);   for(int i=0;i<8;i++){     int xStart = new Random().nextInt(WIDTH);     int yStart = new Random().nextInt(HEIGHT);     int xEnd = new Random().nextInt(WIDTH);     int yEnd = new Random().nextInt(HEIGHT);     graphics.drawLine(xStart, yStart, xEnd, yEnd);   }   //写随机数   graphics.setColor(Color.RED);   int x = 5;   for(int i=0;i<4;i++){     graphics.drawString(new Random().nextInt(9)+"", x, 20);     x+=30;   }   response.setContentType("image/jpeg");//设置响应格式   ImageIO.write(image, "jpeg", response.getOutputStream());    }