登录的验证码（个人笔记）

登录的验证码

创建一个controller类，写一个生成二维码的方法，启动项目，访问controller的路径

http://127.0.0.1:8080/captcha/code

@Controller
@RequestMapping("/captcha")
public class CaptchaController {

    //像素宽度
    private int width = 130;

    //像素高度
    private int height = 30;

    //验证码文字个数
    private int captchaCount = 6;

    //文字的间隔
    private int space = 16;

    //验证码位置
    private int drawY = 20;

    //验证码的值
    private String code[] = {"A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "P", "Q", "R", "S", "T", "U", "V", "W", "Y", "X", "Z", "1", "2", "3", "4", "5", "6", "7", "8", "9"};

    //生成验证码
    @RequestMapping("code")
    public void captcha(HttpServletRequest request, HttpServletResponse response) throws IOException {
        //在内存中绘制一个图片BufferImage,向这个图片写入文字。
        //创建一个背景透明的图片，使用rgb表示颜色
        BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);

        //获取画笔
        Graphics graphics = image.getGraphics();
        //把画笔变成百色
        graphics.setColor(Color.white);

        //给image花板都涂成白色
        graphics.fillRect(0, 0, width, height);

        //设置字体
        Font font = new Font("微软雅黑", Font.BOLD, 16);
        graphics.setFont(font);
        //设置字体的颜色
        graphics.setColor(Color.BLACK);
        //测试一个字
        //graphics.drawString("超",10,drawY);
        int ran = 0;
        int len = code.length;

        //把验证码保存到buffer中
        StringBuffer buffer = new StringBuffer();

        //循环获取6个值
        for (int i = 0; i < captchaCount; i++) {
            ran = new Random().nextInt(len);
            //设置字体随机颜色
            graphics.setColor(makeColor());
            buffer.append(code[ran]);
            //字体的位置  字体  X坐标 Y坐标
            graphics.drawString(code[ran], (i + 1) * space, drawY);
        }

        //设置干扰线
        for (int i = 0; i < 5; i++) {
            int[] dot = makeLineDot();
            //前两个参数是起点，后两个是终点
            graphics.drawLine(dot[0], dot[1], dot[2], dot[3]);
        }


        //设置没有缓存
        response.setHeader("Prama", "no-cache");
        response.setHeader("Cache-Control", "no-cache");
        //设置过期时间
        response.setDateHeader("Expire", 0);

        //把验证码保存到会话中
        request.getSession().setAttribute("code", buffer.toString());

        //文本格式
        response.setContentType("image/png");

        //输出流
        OutputStream stream = response.getOutputStream();

        /**
         * RenderedImage im 输出的图片,
         * String formatName 图片类型,
         *  ImageOutputStream output 输出的地方
         */
        ImageIO.write(image, "png", stream);
		
        stream.flush();
        stream.close();
    }

    //字体的随机颜色
    private Color makeColor() {
        Random random = new Random();
        int r = random.nextInt(255);
        int g = random.nextInt(255);
        int b = random.nextInt(255);
        return new Color(r, g, b);
    }

    //设置干扰线
    private int[] makeLineDot() {
        Random random = new Random();
        int x1 = random.nextInt(width / 2);
        int y1 = random.nextInt(height);

        int x2 = random.nextInt(width);
        int y2 = random.nextInt(height);
        return new int[]{x1, y1, x2, y2};
    }
}