JavaWeb制作登录验证码实现代码解析-创新互联

图例如下

具体操作如下：

新建一个servlet，代码如下：标记一个WebServlet,

1 @WebServlet(urlPatterns = {"/checkCode"}) //验证码Servlet

绘制验证码图片的核心代码：

int width = 100;
    int height = 50;
    //创建图片对象
    BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);

    //美化图片
    Graphics g = image.getGraphics();
    //1：填充背景
    g.setColor(Color.pink);
    g.fillRect(0, 0, width, height);

    //画边框
    g.setColor(Color.blue);
    g.drawRect(0, 0, width - 1, height - 1);

    //生成一个验证码字符串
    String strCheckCode = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
    Random random = new Random();
    StrCheckCode = "";
    for (int i = 1; i <= 4; i++) {
      int index = random.nextInt(strCheckCode.length());
      char ch = strCheckCode.charAt(index);
      StrCheckCode += ch;//拼接验证码
      g.drawString(ch + "", width / 5 * i, height / 2);
    }

    //画干扰线
    for (int i = 0; i < 5; i++) {
      int x1 = random.nextInt(width);
      int x2 = random.nextInt(width);

      int y1 = random.nextInt(height);
      int y2 = random.nextInt(height);
      g.drawLine(x1, x2, y1, y2);
    }

    //输出，显示出来
    ImageIO.write(image, "jpg", resp.getOutputStream());
  }