生成驗證碼模板

@Controller
@RequestMapping("/images")
public class PicController {
	private int width = 100, height = 30;
	private String source = "1234567890";

	@RequestMapping("pic")
	public void showPic(HttpSession session, HttpServletResponse response) throws Exception {
		BufferedImage buffer = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
		Graphics g = buffer.getGraphics();
		// 設定背景色
		g.setColor(Color.BLACK);
		g.fillRect(0, 0, width, height);

		// 畫邊框
		g.setColor(Color.RED);
		g.drawRect(2, 2, width - 6, height - 6);
		String checkcode = this.generateCheckcode(6);
		session.setAttribute("checkcode", checkcode);
		g.setFont(new Font("宋體", Font.BOLD, 22));
		g.setColor(new Color(55, 77, 200));
		g.drawString(checkcode, 10, height - 10);
		// 隨機產生10個干擾點
		Random rand = new Random();
		for (int i = 0; i < 100; i++) {
			int x = rand.nextInt(width);
			int y = rand.nextInt(height);
			g.drawOval(x, y, 2, 1);
		}
		g.dispose();
		response.setHeader("pragme", "no-cache");
		response.setHeader("cache-control", "no-cache");
		response.setDateHeader("expires", -1);
		response.setContentType("image/jpeg");
		response.resetBuffer();
		ServletOutputStream sos = response.getOutputStream();
		ImageIO.write(buffer, "jpg", sos);
		sos.flush();
		sos.close();

	}
	private String generateCheckcode(int len) {
		char[] res = new char[len];
		Random r = new Random();
		for (int i = 0; i < len; i++) {
			res[i] = source.charAt(r.nextInt(source.length()));
		}
		return new String(res);
	}
}