java 验证码

public class RandomCaptchaGenerator {

	// 随即生成包含验证码的字符串

	public static String random( ) {
	
		// 因为o0,l1很难区分,所以,去掉o,l,y,v,0,1
		String str = "";
		str = "23456789abcdefghijkmnpqrstuwxzh";// 初始化种子

		return RandomStringUtils.random(6, str);// 返回length位的字符串

	}

	/**
	 * 根据要求的数字生成图片,背景为白色,字体大小16,字体颜色黑色粗体
	 * 
	 * @param num
	 *            要生成的字符
	 * @param out
	 *            输出流

	 * @throws IOException
	 */
	public static void createImage(String num, OutputStream out) throws IOException {
		if (num.getBytes().length > 6) {
			throw new IllegalArgumentException(
					"The length of param char cannot exceed 6.");
		}
		// 设定宽度和高度

		int width = 80;

		int height = 30;
		// 在内存中创建图象
		BufferedImage bi = new BufferedImage(width, height,
				BufferedImage.TYPE_INT_RGB);
		// 获取图形上下文

		Graphics2D g = (Graphics2D) bi.getGraphics();
		// 画边框

		java.util.Random random = new java.util.Random();
		g.setColor(Color.white);
		g.fillRect(0, 0, width, height);
		// 设置字体
		Font mFont = new Font("Tahoma", Font.BOLD, 16);
		g.setFont(mFont);
		g.setColor(Color.BLACK);// 设置字体颜色
		// 画认证码,每个认证码在不同的水平位置

		String str1[] = new String[6];
		for (int i = 0; i < str1.length; i++) {
			str1[i] = num.substring(i, i + 1);
			int w = 0;
			int x = (i + 1) % 3;

			// 随即生成验证码字符的水平偏移量

			if (x == random.nextInt(3)) {
				w = 19 - random.nextInt(7);
			} else {
				w = 19 + random.nextInt(7);
			}

			// 随即生成颜色
			Color color1 = new Color(random.nextInt(180), random.nextInt(180),
					random.nextInt(180));
			g.setColor(color1);
			g.drawString(str1[i], 12 * i + 4, w);
		}

		// 随机产生干扰点,并用不同的颜色表示，使图象中的认证码不易被其它程序探测到
		for (int i = 0; i < 100; i++) {
			int x = random.nextInt(width);
			int y = random.nextInt(height);
			Color color1 = new Color(random.nextInt(255), random.nextInt(255),
					random.nextInt(255));
			g.setColor(color1); // 随即画各种颜色的点

			g.drawOval(x, y, 0, 0);
		}
		// 画干扰线
		for (int i = 0; i < 0; i++) {
			int x = random.nextInt(width);
			int y = random.nextInt(height);
			int x1 = random.nextInt(width);
			int y1 = random.nextInt(height);
			Color color1 = new Color(random.nextInt(255), random.nextInt(255),
					random.nextInt(255));

			g.setColor(color1); // 随即画各种颜色的线

			g.drawLine(x, y, x1, y1);
		}
		// 图像生效
		g.dispose();
		// 输出页面
		ImageIO.write(bi, "jpg", out);
		out.close();
	}

	public static void main(String[] args) throws IOException {
		String num = random();
		System.out.println(num);
		createImage(num, new FileOutputStream("D:/test.jpg"));
		System.out.println("Image generated.");
	}
}