Spring Boot整合Security系列步驟及問題排查（八）—— 自定義圖形驗證碼生成邏輯可配置

1.新建驗證碼生成接口：

/**
 * 驗證碼生成邏輯抽象類
 *
 * @author zhaohaibin
 */
public interface ValidateCodeGenerator {

    /**
     * 驗證碼生成抽象方法
     *
     * @param request
     * @return
     */
    ImageCode generate(ServletWebRequest request);

}

2.接口實現，將ValidateCodeController實現邏輯提出：

/**
 * 驗證碼生成邏輯實現類-圖片驗證碼
 *
 * @author zhaohaibin
 */
@Data
public class ImageCodeGenerator implements ValidateCodeGenerator {

    @Autowired
    private SecurityProperties securityProperties;

    @Override
    public ImageCode generate(ServletWebRequest request) {

        // 請求配置覆蓋自定義配置覆蓋默認配置
        int width = ServletRequestUtils.getIntParameter(request.getRequest(), "width", securityProperties.getCode().getImage().getWidth());
        int height = ServletRequestUtils.getIntParameter(request.getRequest(), "height", securityProperties.getCode().getImage().getHeight());

        BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);

        Graphics g = image.getGraphics();

        Random random = new Random();

        g.setColor(getRandColor(200, 250));
        g.fillRect(0, 0, width, height);
        g.setFont(new Font("Times New Roman", Font.ITALIC, 20));
        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);
        }

        String sRand = "";
        for (int i = 0; i < securityProperties.getCode().getImage().getLength(); i++) {
            String rand = String.valueOf(random.nextInt(10));
            sRand += rand;
            g.setColor(new Color(20 + random.nextInt(110), 20 + random.nextInt(110), 20 + random.nextInt(110)));
            g.drawString(rand, 13 * i + 6, 16);
        }

        g.dispose();

        return new ImageCode(image, sRand, securityProperties.getCode().getImage().getExpireIn());

    }

    /**
     * 生成隨機背景條紋
     *
     * @param fc
     * @param bc
     * @return
     */
    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);
    }

}

3.更新ValidateCodeController調用：

@Autowired
private ValidateCodeGenerator imageCodeGenerator;

@GetMapping("/code/image")
public void createCode(HttpServletRequest request, HttpServletResponse response) throws IOException {
    ImageCode imageCode = imageCodeGenerator.generate(new ServletWebRequest(request));
    sessionStrategy.setAttribute(new ServletWebRequest(request), SESSION_KEY, imageCode);
    ImageIO.write(imageCode.getImage(), "JPEG", response.getOutputStream());
}

4.ValidateCodeGenerator註解@Component的替代方案，方便自定義生成邏輯的覆寫：

/**
 * 生成器實現方式可配置
 * 效果同@Component，但是可以配置@ConditionalOnMissingBean，這樣會優先尋找匹配name的生成實現方法
 *
 * @author zhaohaibin
 */
@Configuration
public class ValidateCodeBeanConfig {

    @Autowired
    private SecurityProperties securityProperties;

    @Bean
    @ConditionalOnMissingBean(name = "imageCodeGenerator")
    public ValidateCodeGenerator imageCodeGenerator() {
        ImageCodeGenerator codeGenerator = new ImageCodeGenerator();
        codeGenerator.setSecurityProperties(securityProperties);
        return codeGenerator;
    }

}   

5.測試自定義生成邏輯：

/**
 * 自定義驗證碼生成邏輯
 *
 * @author zhaohaibin
 */
//@Component("imageCodeGenerator")
@Slf4j
public class DemoImageCodeGenerator implements ValidateCodeGenerator {
    @Override
    public ImageCode generate(ServletWebRequest request) {
        log.info("更高級的圖形驗證碼生成邏輯");
        return null;
    }
}

6.啓動測試，圖片不顯示，控制檯打印日誌並報空指針異常表示成功：

INFO (DemoImageCodeGenerator.java:17)- 更高級的圖形驗證碼生成邏輯
...
java.lang.NullPointerException: null

問題排查：
暫無