1.导入依赖

<dependency>
    <groupId>com.github.penggle</groupId>
    <artifactId>kaptcha</artifactId>
</dependency>

2.创建KaptchaImageCodeConfig

package com.mengxuegu.security.authentication.code;

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

import java.util.Properties;

@Configuration
public class KaptchaImageCodeConfig {
    @Bean
    public DefaultKaptcha getDefaultKaptcha(){
        DefaultKaptcha defaultKaptcha = new DefaultKaptcha();
        Properties properties = new Properties();
        properties.setProperty(Constants.KAPTCHA_BORDER, "yes");
        properties.setProperty(Constants.KAPTCHA_BORDER_COLOR, "192,192,192");
        properties.setProperty(Constants.KAPTCHA_IMAGE_WIDTH, "110");
        properties.setProperty(Constants.KAPTCHA_IMAGE_HEIGHT, "36");
        properties.setProperty(Constants.KAPTCHA_TEXTPRODUCER_FONT_COLOR, "blue");
        properties.setProperty(Constants.KAPTCHA_TEXTPRODUCER_FONT_SIZE, "28");
        properties.setProperty(Constants.KAPTCHA_TEXTPRODUCER_FONT_NAMES, "宋体");
        properties.setProperty(Constants.KAPTCHA_TEXTPRODUCER_CHAR_LENGTH, "4");
        properties.setProperty(Constants.KAPTCHA_TEXTPRODUCER_CHAR_STRING, "0123456789");
        properties.setProperty(Constants.KAPTCHA_NOISE_IMPL,"com.google.code.kaptcha.impl.NoNoise");
        // 图片效果
        properties.setProperty(Constants.KAPTCHA_OBSCURIFICATOR_IMPL,
                "com.google.code.kaptcha.impl.ShadowGimpy");
        Config config = new Config(properties);
        defaultKaptcha.setConfig(config);
        return defaultKaptcha;
    }
}

3.在控制器中调用

package com.mengxuegu.security.controller;

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.RequestMapping;

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.IOException;

@Controller
public class CustomLoginController {

    @Autowired
    private DefaultKaptcha defaultKaptcha;

    public static final String SESSION_KEY = "SESSION_KEY_IMAGE_CODE";

    /**
     * 获取图形验证码
     */
    @RequestMapping("/code/image")
    public void imageCode(HttpServletRequest request, HttpServletResponse response) throws IOException {
        //1.获取验证码字符串
        String code = defaultKaptcha.createText();
        //2.字符串把它放到session中
        request.getSession().setAttribute(SESSION_KEY,code);
        //3.获取验证码图片
        BufferedImage image = defaultKaptcha.createImage(code);
        //4.将验证码图片把它写出去
        ServletOutputStream outputStream = response.getOutputStream();
        ImageIO.write(image,"jpg",outputStream);
    }
}