java生成图形验证码（算数运算图形验证码 + 随机字符图形验证码）

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# 生成图形验证码（算数运算图形验证码 + 随机字符图形验证码） #

## 1 场景 ##

在用户登录、忘记密码、用户注册、修改用户信息....等场景需要对用户进行图形化验证。防止别有用心的人或机器通过接口来进行攻击或恶意操作。

本示例讲解通过java生成两种图形验证码：算数运算的图形验证码和定长随机字符图形验证码！

## 2 编写代码 ##

### 2.1 创建生成指定长度的随机字符串工具类 ###

创建生成指定长度的随机字符串工具类：RandomCodeUtil.java，该工具类在之前的博客中讲到过。

import java.util.Random;
    
    /**
     * 生成指定长度的随机字符串
     */
    public class RandomCodeUtil {
    
      /**
       * 生成指定长度的随机字符串（不包含数字0，和字母l、o和i）
       *
       * @param capacity 验证码长度
       */
      public static String genCode(Integer capacity) {
        //随机字符集（不包含数字0和字母o、i和l）
        String str = "abcdefghjkmnpqrstuvwxyz123456789";
        Random rand = new Random();
        StringBuilder a = new StringBuilder();
        for (int i = 0; i < capacity; i++) {
          char c = str.charAt(rand.nextInt(str.length()));
          a.append(c);
        }
        return a.toString();
      }
    
      public static void main(String[] args) {
        //生产6位长度的随机验证码
        System.out.println(RandomCodeUtil.genCode(6));
      }
    }

### 2.2 创建图形验证码工具类 ###

创建图形验证码工具类：ImgCodeUtil.java

import java.awt.Color;
    import java.awt.Font;
    import java.awt.Graphics2D;
    import java.awt.image.BufferedImage;
    import java.io.FileOutputStream;
    import java.io.IOException;
    import java.io.OutputStream;
    import java.util.Random;
    import javax.imageio.ImageIO;
    
    /**
     * 生成图形验证码工具类
     */
    public class ImgCodeUtil {
    
      /**
       * 图片的宽度
       */
      private Integer width = 120;
    
      /**
       * 图片的高度
       */
      private Integer height = 40;
    
      /**
       * 验证码干扰线条数
       */
      private Integer lineCount = 8;
    
      /**
       * 验证码code
       */
      private String validateCode = null;
    
      /**
       * 验证码图片Buffer
       */
      private BufferedImage buffImg = null;
    
      /**
       * 构造方法
       */
      public ImgCodeUtil(String validateCode) {
        this.validateCode = validateCode;
        this.createCode();
      }
    
      /**
       * 构造方法
       */
      public ImgCodeUtil(String validateCode, int width, int height) {
        this.width = width;
        this.height = height;
        this.validateCode = validateCode;
        this.createCode();
      }
    
      /**
       * 生成验证码图片
       */
      private void createCode() {
        int x = 0;
        int fontHeight;
        int codeY = 0;
        int red = 0;
        int green = 0;
        int blue = 0;
        int codeCount = validateCode.length();
        //每个字符的宽度
        x = width / codeCount;
        //字体的高度
        fontHeight = height - 2;
        codeY = height - 4;
    
        // 图像buffer
        buffImg = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
        Graphics2D g = buffImg.createGraphics();
        // 生成随机数
        Random random = new Random();
        // 将图像填充为白色
        g.setColor(Color.WHITE);
        g.fillRect(0, 0, width, height);
    
        //图片划线
        for (int i = 0; i < lineCount; i++) {
          int xs = random.nextInt(width / 2);
          int ys = random.nextInt(height);
          int xe = random.nextInt(width / 2) + width / 2;
          int ye = random.nextInt(height);
          red = random.nextInt(255);
          green = random.nextInt(255);
          blue = random.nextInt(255);
          g.setColor(new Color(red, green, blue));
          g.drawLine(xs, ys, xe, ye);
        }
    
        Font font = new Font("Arial", Font.BOLD, fontHeight);
        g.setFont(font);
        // 将验证码写入图片
        for (int i = 0; i < codeCount; i++) {
          red = random.nextInt(255);
          green = random.nextInt(255);
          blue = random.nextInt(255);
          g.setColor(new Color(red, green, blue));
          g.drawString(String.valueOf(validateCode.charAt(i)), i * x, codeY);
        }
      }
    
      /**
       * 输出图片到指定路径
       */
      public void write(String path) throws IOException {
        OutputStream outputStream = new FileOutputStream(path);
        this.write(outputStream);
      }
    
      /**
       * 将图片输出到输出流中
       */
      public void write(OutputStream outputStream) throws IOException {
        ImageIO.write(buffImg, "png", outputStream);
        outputStream.close();
      }
    
      public BufferedImage getBuffImg() {
        return buffImg;
      }
    }

### 2.3 创建图形验证码接口类 ###

创建图形验证码接口类：ValidateCodeService.java

import com.xxx.alltest.dto.CheckCode;
    import com.xxx.alltest.entity.ValidateCode;
    
    /**
     * 图形验证码接口类
     */
    public interface ValidateCodeService {
    
      /**
       * 生成算数运算图形验证码
       */
      ValidateCode generateMathImgCode(Integer width, Integer height);
    
      /**
       * 生成随机字符串图形验证码
       */
      ValidateCode generateRandomImgCode(Integer width, Integer height);
    
      /**
       * 校验图形验证码值
       */
      String checkValidateCode(CheckCode checkCode);
    }

### 2.4 创建图形验证码接口实现类 ###

图形验证码接口实现类：ValidateCodeServiceImpl.java

import com.xxx.alltest.dto.CheckCode;
    import com.xxx.alltest.entity.ValidateCode;
    import com.xxx.alltest.service.ValidateCodeService;
    import com.xxx.alltest.utils.ImgCodeUtil;
    import com.xxx.alltest.utils.RandomCodeUtil;
    import java.awt.image.BufferedImage;
    import java.io.ByteArrayOutputStream;
    import java.io.IOException;
    import java.util.Objects;
    import java.util.UUID;
    import javax.imageio.ImageIO;
    import lombok.extern.slf4j.Slf4j;
    import org.apache.commons.lang3.RandomUtils;
    import org.springframework.stereotype.Service;
    import org.springframework.util.Base64Utils;
    import org.springframework.util.StringUtils;
    
    /**
     * 图形验证码接口实现类
     */
    @Slf4j
    @Service
    public class ValidateCodeServiceImpl implements ValidateCodeService {
    
      /**
       * 验证码过期时间：5分钟
       */
      private static final Long EXPIRE_TIME = 5 * 60 * 1000L;
    
      /**
       * 生成算数运算图形验证码
       */
      @Override
      public ValidateCode generateMathImgCode(Integer width, Integer height) {
        Integer firstNum = RandomUtils.nextInt() % 10 + 1;
        Integer secondNum = RandomUtils.nextInt() % 10 + 1;
        Integer validateCode = firstNum + secondNum;
        ImgCodeUtil imgCodeUtil = new ImgCodeUtil(firstNum + "+" + secondNum + "=?", width, height);
        BufferedImage buffImg = imgCodeUtil.getBuffImg();
        ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
    
        String base64ImgCode = null;
        String uuid = UUID.randomUUID().toString().replaceAll("-", "");
        try {
          ImageIO.write(buffImg, "png", byteArrayOutputStream);
          byte[] bytes = byteArrayOutputStream.toByteArray();
          base64ImgCode = Base64Utils.encodeToString(bytes);
          //将生成的验证码缓存起来
    //            redisTemplate.set(String.join(":", "mathImgCode", uuid), validateCode.toString(), EXPIRE_TIME);
        } catch (IOException var10) {
          log.error("生成算数运算图形验证码失败");
        }
        return ValidateCode.builder()
            .base64ImgCode(base64ImgCode)
            .uuid(uuid)
            .build();
      }
    
      /**
       * 生成随机字符串图形验证码
       */
      @Override
      public ValidateCode generateRandomImgCode(Integer width, Integer height) {
        String validateCode = RandomCodeUtil.genCode(4);
        ImgCodeUtil imgCodeUtil = new ImgCodeUtil(validateCode, width, height);
        BufferedImage buffImg = imgCodeUtil.getBuffImg();
        ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
    
        String base64ImgCode = null;
        String uuid = UUID.randomUUID().toString().replaceAll("-", "");
        try {
          ImageIO.write(buffImg, "png", byteArrayOutputStream);
          byte[] bytes = byteArrayOutputStream.toByteArray();
          base64ImgCode = Base64Utils.encodeToString(bytes);
          //将生成的验证码缓存起来
    //            redisTemplate.set(String.join(":", "randomImgCode", uuid), validateCode, EXPIRE_TIME);
        } catch (IOException var10) {
          log.error("生成随机字符串图形验证码失败");
        }
        return ValidateCode.builder()
            .base64ImgCode(base64ImgCode)
            .uuid(uuid)
            .build();
      }
    
      /**
       * 校验图形验证码值
       */
      @Override
      public String checkValidateCode(CheckCode checkCode) {
        String redisCode = null;
    //        String redisCode = redisTemplate.get(String.join(":", "randomImgCode", checkCode.getUuid()));
        if (StringUtils.isEmpty(redisCode)) {
          return "验证码已过期";
        }
        if (!Objects.equals(checkCode.getValidateCode(), redisCode)) {
          return "验证码错误";
        }
        return null;
      }
    }

### 2.5 创建验证码相关api接口类 ###

创建验证码相关api接口类：ValidateCodeController.java

import com.xxx.alltest.all.oss.common.Result;
    import com.xxx.alltest.dto.CheckCode;
    import com.xxx.alltest.entity.ValidateCode;
    import com.xxx.alltest.service.ValidateCodeService;
    import java.util.Objects;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.util.StringUtils;
    import org.springframework.web.bind.annotation.GetMapping;
    import org.springframework.web.bind.annotation.PostMapping;
    import org.springframework.web.bind.annotation.RequestBody;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RequestParam;
    import org.springframework.web.bind.annotation.RestController;
    
    /**
     * 验证码相关api接口
     */
    @RestController
    @RequestMapping("/validate")
    public class ValidateCodeController {
    
      @Autowired
      private ValidateCodeService validateCodeService;
    
      /**
       * 生成图形验证码
       *
       * @param type 0-普通字符图形验证码（如：1a4h）  1-算数图形验证码（1+8=?）
       */
      @GetMapping("generate")
      public Result<ValidateCode> generate(@RequestParam(value = "type", defaultValue = "0") String type,
          @RequestParam(value = "width", defaultValue = "100") Integer width,
          @RequestParam(value = "height", defaultValue = "40") Integer height) {
        ValidateCode validateCode = null;
        if (Objects.equals("0", type)) {
          validateCode = validateCodeService.generateRandomImgCode(width, height);
        } else {
          validateCode = validateCodeService.generateMathImgCode(width, height);
        }
    
        if (StringUtils.isEmpty(validateCode.getBase64ImgCode())) {
          return Result.failed("生成图形验证码失败");
        } else {
          return Result.ok(validateCode);
        }
      }
    
      /**
       * 校验图形验证码
       */
      @PostMapping("check")
      public Result check(@RequestBody CheckCode checkCode) {
        String msg = validateCodeService.checkValidateCode(checkCode);
        if (!StringUtils.isEmpty(msg)) {
          return Result.failed(msg);
        }
        return Result.ok();
      }
    }

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