Java Verify Code image

 /**Java 

 *  create an image of the verify code
 */
public class VerifyCode {
	private int width = 100; // width of image
	private int height = 50;// height
	private String[] fontNames = { "Serif", "Sans Serif", "Slab Serif", "宋体", "楷体", "隶书", "微软雅黑" };
	private Color bgColor = new Color(255, 255, 255);// background
	private Random random = new Random();
	private String codes = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
	private String text;// random

	/**
	 * get Color 
	 * @return
	 */
	private Color randomColor() {
		int red = random.nextInt(150);
		int green = random.nextInt(150);
		int blue = random.nextInt(150);
		return new Color(red, green, blue);
	}

	/**
	 * font type
	 * @return
	 */
	private Font randomFont() {
		String name = fontNames[random.nextInt(fontNames.length)];
		int style = random.nextInt(4);
		int size = random.nextInt(5) + 24;
		return new Font(name, style, size);
	}

	private char randomChar() {
		return codes.charAt(random.nextInt(codes.length()));
	}

	/**
	 * create a BufferedImage
	 * @return
	 */
	private BufferedImage createImage() {
		BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
		Graphics2D g2 = (Graphics2D) image.getGraphics();
		g2.setColor(bgColor);
		g2.fillRect(0, 0, width, height);
		return image;
	}
	public BufferedImage getImage() {
		BufferedImage image = createImage();
		Graphics2D g2 = (Graphics2D) image.getGraphics();
		StringBuffer sb = new StringBuffer();
		for (int i = 0; i < 4; i++) {
			String s = randomChar() + "";
			sb.append(s);
			g2.setColor(randomColor());
			g2.setFont(randomFont());
			float x = i * width * 1.0f / 4;
			g2.drawString(s, x, height - 15);
		}
		this.text = sb.toString();
		drawLine(image);
		return image;
	}
	private void drawLine(BufferedImage image) {
		Graphics2D g2 = (Graphics2D) image.getGraphics();
		int num = 5;
		for (int i = 0; i < num; i++) {
			int x1 = random.nextInt(width);
			int y1 = random.nextInt(height);
			int x2 = random.nextInt(width);
			int y2 = random.nextInt(height);
			g2.setColor(randomColor());
			g2.setStroke(new BasicStroke(1.5f));
			g2.drawLine(x1, y1, x2, y2);
		}
	}

	public String getText() {
		return text;
	}

	public static void output(BufferedImage image, OutputStream out) throws IOException {
		ImageIO.write(image, "JPEG", out);
	}
}

Controller ：

@RestController
public class VerifyCodeController {
    @GetMapping("/vercode")
    public void code(HttpServletRequest req, HttpServletResponse resp) throws IOException {
        VerifyCode vc = new VerifyCode();
        BufferedImage image = vc.getImage();
        String text = vc.getText();
        HttpSession session = req.getSession();
        session.setAttribute("index_code", text);
        VerifyCode.output(image, resp.getOutputStream());
    }
}

<img src="/vercode" alt="">

@Component
public class VerifyCodeFilter extends GenericFilterBean {
    private String defaultFilterProcessUrl = "/doLogin";

    @Override
    public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain)
            throws IOException, ServletException {
        HttpServletRequest request = (HttpServletRequest) req;
        HttpServletResponse response = (HttpServletResponse) res;
        if ("POST".equalsIgnoreCase(request.getMethod()) && defaultFilterProcessUrl.equals(request.getServletPath())) {
            // 验证码验证
            String requestCaptcha = request.getParameter("code");
            String genCaptcha = (String) request.getSession().getAttribute("index_code");
            if (StringUtils.isEmpty(requestCaptcha))
                throw new AuthenticationServiceException("验证码不能为空!");
            if (!genCaptcha.toLowerCase().equals(requestCaptcha.toLowerCase())) {
                throw new AuthenticationServiceException("验证码错误!");
            }
        }
        chain.doFilter(request, response);
    }
}

Spring Security 

@Configuration
public class SecurityConfig extends WebSecurityConfigurerAdapter {

    @Autowired
    VerifyCodeFilter verifyCodeFilter;
    ...
    ...
    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http.addFilterBefore(verifyCodeFilter, UsernamePasswordAuthenticationFilter.class);
        http.authorizeRequests()
                .antMatchers("/admin/**").hasRole("admin")
                ...
                ...
                .permitAll()
                .and()
                .csrf().disable();
    }
}