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()); }

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