Java实现验证码

时间:2022-11-29 20:45:14

 

一、验证码工具类

public class CheckCodeUtil {
    
    private BufferedImage image; // 图像
    private String str; // 验证码
    
    private RandomNumUtil () {
        init();
    }
    
    // 获取实例
    public static RandomNumUtil Instance() {
        return new RandomNumUtil();
    }
    
    // 获取图片
    public RenderedImage getImage() {
        return this.image;
    }
    
    // 获取6位随机验证码
    public String getStr() {
        return this.str;
    }
    
    private void init() {
        // 在内存中创建图象,设置图像的宽高
        int width = 120, height = 30;
        BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
        // 获取图形上下文
        Graphics g = image.getGraphics();
        // 生成随机类
        Random random = new Random();
        // 设定背景色
        g.setColor(getRandColor(200, 250));
        g.fillRect(0, 0, width, height);
        // 设定字体
        g.setFont(new Font("Times New Roman", Font.PLAIN, height - 4));
        // 随机产生155条干扰线,使图象中的认证码不易被其它程序探测到
        g.setColor(getRandColor(160, 200));
        for (int i = 0; i < 155; i++) {
            int x = random.nextInt(width);
            int y = random.nextInt(height);
            int xl = random.nextInt(12);
            int yl = random.nextInt(12);
            g.drawLine(x, y, x + xl, y + yl);
        }
        // 取随机产生的认证码(4位数字)
        String sRand = "";
        for (int i = 0; i < 4; i++) {
            String rand = String.valueOf(random.nextInt(10));
            sRand += rand;
            // 将认证码显示到图象中
            g.setColor(new Color(20 + random.nextInt(110), 20 + random.nextInt(110), 20 + random.nextInt(110)));
            // 调用函数出来的颜色相同,可能是因为种子太接近,所以只能直接生成
            g.drawString(rand, 13 * i + 26, 25);
        }
        // 赋值验证码
        this.str = sRand;
        // 图象生效
        g.dispose();
        this.image = image;
    }

    // 给定范围获得随机颜色
    private Color getRandColor(int fc, int bc) {
        Random random = new Random();
        if (fc > 255)
            fc = 255;
        if (bc > 255)
            bc = 255;
        int r = fc + random.nextInt(bc - fc);
        int g = fc + random.nextInt(bc - fc);
        int b = fc + random.nextInt(bc - fc);
        return new Color(r, g, b);
    }
}

 

二、获取验证码

@RequestMapping(value = "/check/code")
public void init(HttpServletRequest request, HttpServletResponse response) { 
    try {
      // 生成验证码实例
    CheckCodeUtil util = ChecoCodeUtil.Instance();
    request.getSession().setAttribute("sessionCode", util.getStr());
    ServletOutputStream stream = response.getOutputStream();
    ImageIO.write(util.getImage(), "JPEG", stream);
    stream.flush();
    stream.close();
  } catch (IOException e) {
    System.out.println("验证码生成失败");
  }
}

 

三、页面

<img src="check/code" id="imgObj" alt="验证码">

 

四、效果

Java实现验证码