生成图形验证码

创建实体类

import lombok.Data;

import java.io.Serializable;

@Data
public class VerifyVO implements Serializable {
    private String verifyString;
    private String verifyBase64;
    private String key;
}

图形验证码生成工具

import lombok.extern.slf4j.Slf4j;
import org.apache.commons.codec.binary.Base64;
import sun.font.FontDesignMetrics;

import javax.imageio.ImageIO;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.util.Random;
import java.util.UUID;

/**
 * 生成图形验证码
 */
@Slf4j
public class VerifyUtil {

    /**
     * 随机产生数字与字母组合的字符串
     * 去掉了1,0,i,o几个容易混淆的字符
     */
    private static final String RAND_STRING = "23456789ABCDEFGHJKLMNPQRSTUVWXYZ";

    /**
     * 图片默认宽
     */
    private static final int WIDTH = 82;

    /**
     * 图片默认高
     */
    private static final int HEIGHT = 24;

    /**
     * 随机产生字符最大和最小数量
     */
    private static final int MIN_STRING_NUM = 4;
    private static final int MAX_STRING_NUM = 6;

    /**
     * 字体大小
     */
    private static final int FONT_SIZE  = 20;

    private static final Random RANDOM = new Random();

    public static VerifyVO getRandCode(int w,int h, int num) {

        //字符数量
        int strNum = Math.max(MIN_STRING_NUM, num);
        strNum = Math.min(MAX_STRING_NUM, strNum);

        //宽度
        int width  = Math.max(WIDTH, w);
        width = Math.max(width, strNum * FONT_SIZE);

        //高度
        int height = Math.max(HEIGHT, h);

        //间距
        int padding = (width - strNum * FONT_SIZE) / 2;

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

        //产生Image对象的Graphics对象,改对象可以在图像上进行各种绘制操作
        Graphics2D graphics =  image.createGraphics();
        graphics.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON);

        //背景色 纯白
        graphics.setBackground(Color.WHITE);

        //图片大小
        graphics.fillRect(0, 0, width, height);

        //文字颜色
        graphics.setColor(new Color(54,141,255));

        //字体
        Font font = new Font("Fixedsys", Font.BOLD, 20);
        graphics.setFont(font);

        //字体基准信息
        FontDesignMetrics metrics = FontDesignMetrics.getMetrics(font);

        // 绘制随机字符
        StringBuilder randomString = new StringBuilder();

        for (int i = 0; i < strNum; i++) {

            String rand = getRandomString(RANDOM.nextInt(RAND_STRING.length()));

            int x = FONT_SIZE * i + padding + (FONT_SIZE - metrics.stringWidth(rand)) / 2;

            //graphics.translate(RANDOM.nextInt(3), RANDOM.nextInt(3));

            graphics.drawString(rand, x, metrics.getAscent());

            randomString.append(rand);
        }

        graphics.dispose();

        VerifyVO vo = new VerifyVO();
        vo.setVerifyBase64(bufferedImageToBase64(image));
        vo.setKey(UUID.randomUUID().toString());
        vo.setVerifyString(randomString.toString());

        return vo;
    }

    private static String bufferedImageToBase64(BufferedImage bufferedImage) {

        ByteArrayOutputStream stream = new ByteArrayOutputStream();

        try {

            ImageIO.write(bufferedImage, "png", stream);
            Base64 base = new Base64();
            String base64 = base.encodeToString(stream.toByteArray());
            stream.close();

            return "data:image/png;base64," + base64;

        }catch (IOException e) {
            throw new RuntimeException("验证码生成异常");
        }

    }

    /**
     * 获取随机的字符
     */
    public static String getRandomString(int num) {
        return String.valueOf(RAND_STRING.charAt(num));
    }

    public static void main(String[] args) {

        VerifyVO randCode = VerifyUtil.getRandCode(82, 28,4);

        System.out.println(randCode.getVerifyBase64());

    }
}

测试

运行main方法：

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