Java generates image verification code

Picture verification code usage scenarios

• Login registration: A means to distinguish between machines and humans. Its greatest role is to prevent violent login or attacks by robot programs
• SMS sending: It can effectively avoid malicious attacks on customer websites or APPs and prevent financial losses

Method to realize

1. Add Maven dependency

	   <dependency>
            <groupId>com.github.whvcse</groupId>
            <artifactId>easy-captcha</artifactId>
            <version>1.6.2</version>
        </dependency>

2. Add an interface for obtaining image verification codes

	@ApiOperation("获取图片验证码")
    @GetMapping("/captcha")
    public void captcha(HttpServletRequest request, HttpServletResponse response) {
    
    
        commService.create(request, response);
    }

Note: When obtaining the image verification code, you need to add a parameter key after the request address , and the key must be unique

3. Implementation method

 	@Override
    public void create(HttpServletRequest request, HttpServletResponse response) {
    
    
        String key = request.getParameter("key");
        if (StringUtils.isBlank(key)) {
    
    
            throw new NingException(500,"请输入key码");
        }
        ValidateCodeProperties code = new ValidateCodeProperties();
        setHeader(response, code.getType());
        Captcha captcha = createCaptcha(code);
        // 把验证码存进缓存中
        dataCache.setCacheImageValidCode(key, StringUtils.lowerCase(captcha.text()));
        try {
    
    
            captcha.out(response.getOutputStream());
        } catch (IOException e) {
    
    
            e.printStackTrace();
            throw new NingException(500,"图形验证码生成失败，请稍后再试！");
        }
    }

	  private Captcha createCaptcha(ValidateCodeProperties code) {
    
    
        Captcha captcha = null;
        if (StringUtils.equalsIgnoreCase(code.getType(), "gif")) {
    
    
            captcha = new GifCaptcha(code.getWidth(), code.getHeight(), code.getLength());
        } else {
    
    
            captcha = new SpecCaptcha(code.getWidth(), code.getHeight(), code.getLength());
        }
        captcha.setCharType(code.getCharType());
        return captcha;
    }

	 private void setHeader(HttpServletResponse response, String type) {
    
    

        if (StringUtils.equalsIgnoreCase(type, "gif")) {
    
    
            response.setContentType(MediaType.IMAGE_GIF_VALUE);
        } else {
    
    
            response.setContentType(MediaType.IMAGE_PNG_VALUE);
        }
        response.setHeader(HttpHeaders.PRAGMA, "No-cache");
        response.setHeader(HttpHeaders.CACHE_CONTROL, "no-cache");
        response.setDateHeader(HttpHeaders.EXPIRES, 0L);
    }

3. Image verification code configuration class

@Data
public class ValidateCodeProperties {
    
    
    /**
     * 验证码有效时间，单位秒
     */
    private Long time = 120L;
    /**
     * 验证码类型，可选值 png和 gif
     */
    private String type = "png";
    /**
     * 图片宽度，px
     */
    private Integer width = 130;
    /**
     * 图片高度，px
     */
    private Integer height = 48;
    /**
     * 验证码位数
     */
    private Integer length = 4;
    /**
     * 验证码值的类型
     * 1. 数字加字母
     * 2. 纯数字
     * 3. 纯字母
     */
    private Integer charType = 2;
}

5.OK, let’s work together~, the effect is on