Use kaptcha to complete the login dynamic verification code

Renderings

 Click to toggle an effect of the verification code

Front page

Thymeleaf is used here

Backend implementation

Import pom dependencies

        <!-- 验证码 -->
        <dependency>
            <groupId>com.github.penggle</groupId>
            <artifactId>kaptcha</artifactId>
            <version>2.3.2</version>
        </dependency>

Create kaptcha configuration class

import com.google.code.kaptcha.impl.DefaultKaptcha;
import com.google.code.kaptcha.util.Config;
import org.springframework.context.annotation.Bean;
import org.springframework.stereotype.Component;

import java.util.Properties;

@Component
public class KaptchaConfig {
    @Bean
    public DefaultKaptcha getDefaultKaptcha() {
        DefaultKaptcha defaultKaptcha = new DefaultKaptcha();
        Properties properties = new Properties();
        properties.put("kaptcha.border", "no");
        properties.put("kaptcha.textproducer.font.color", "black");
        properties.put("kaptcha.image.width", "150");
        properties.put("kaptcha.image.height", "40");
        properties.put("kaptcha.textproducer.font.size", "30");
        properties.put("kaptcha.session.key", "verifyCode");
        //设置验证码字符数量
        properties.put("kaptcha.textproducer.char.space", "5");
        Config config = new Config(properties);
        defaultKaptcha.setConfig(config);

        return defaultKaptcha;
    }
}

Create a controller to receive a verification code request

import com.google.code.kaptcha.impl.DefaultKaptcha;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;

import javax.imageio.ImageIO;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.awt.image.BufferedImage;
import java.io.ByteArrayOutputStream;

@Controller
public class CommonController {

    @Autowired
    private DefaultKaptcha captchaProducer;

    @GetMapping("/common/kaptcha")
    public void defaultKapcha(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse) throws Exception {
        byte[] captchaOutputStream = null;
        ByteArrayOutputStream imgOutputStream = new ByteArrayOutputStream();
        try {
            //生产验证码字符串并保存到session中
            String verifyCode = captchaProducer.createText();
            httpServletRequest.getSession().setAttribute("verifyCode", verifyCode);
            //根据验证码字符创建图片
            BufferedImage challenge = captchaProducer.createImage(verifyCode);
            //图片写入
            ImageIO.write(challenge, "jpg", imgOutputStream);
        } catch (IllegalArgumentException e) {
            httpServletResponse.sendError(HttpServletResponse.SC_NOT_FOUND);
            return;
        }
        captchaOutputStream = imgOutputStream.toByteArray();
        httpServletResponse.setHeader("Cache-Control", "no-store");
        httpServletResponse.setHeader("Pragma", "no-cache");
        httpServletResponse.setDateHeader("Expires", 0);
        httpServletResponse.setContentType("image/jpeg");
        ServletOutputStream responseOutputStream = httpServletResponse.getOutputStream();
        responseOutputStream.write(captchaOutputStream);
        responseOutputStream.flush();
        responseOutputStream.close();
    }
}