content: package org.jeecg.modules.system.util;
  
  import javax.imageio.ImageIO;
  import javax.servlet.http.HttpServletResponse;
  import java.awt.*;
  import java.awt.image.BufferedImage;
  import java.io.ByteArrayOutputStream;
  import java.io.IOException;
  import java.util.Base64;
  import java.util.Random;
  
  /**
   * 登录验证码工具类
   */
  public class RandImageUtil {
  
      public static final String key = "JEECG_LOGIN_KEY";
  
      /**
       * 定义图形大小
       */
      private static final int width = 105;
      /**
       * 定义图形大小
       */
      private static final int height = 35;
  
      /**
       * 定义干扰线数量
       */
      private static final int count = 200;
  
      /**
       * 干扰线的长度=1.414*lineWidth
       */
      private static final int lineWidth = 2;
  
      /**
       * 图片格式
       */
      private static final String IMG_FORMAT = "JPEG";
  
      /**
       * base64 图片前缀
       */
      private static final String BASE64_PRE = "data:image/jpg;base64,";
  
      /**
       * 直接通过response 返回图片
       * @param response
       * @param resultCode
       * @throws IOException
       */
      public static void generate(HttpServletResponse response, String resultCode) throws IOException {
          BufferedImage image = getImageBuffer(resultCode);
          // 输出图象到页面
          ImageIO.write(image, IMG_FORMAT, response.getOutputStream());
      }
  
      /**
       * 生成base64字符串
       * @param resultCode
       * @return
       * @throws IOException
       */
      public static String generate(String resultCode) throws IOException {
          BufferedImage image = getImageBuffer(resultCode);
  
          ByteArrayOutputStream byteStream = new ByteArrayOutputStream();
          //写入流中
          ImageIO.write(image, IMG_FORMAT, byteStream);
          //转换成字节
          byte[] bytes = byteStream.toByteArray();
          //转换成base64串
          String base64 = Base64.getEncoder().encodeToString(bytes).trim();
          base64 = base64.replaceAll("\n", "").replaceAll("\r", "");//删除 \r\n
  
          //写到指定位置
          //ImageIO.write(bufferedImage, "png", new File(""));
  
          return BASE64_PRE+base64;
      }
  
      private static BufferedImage getImageBuffer(String resultCode){
          // 在内存中创建图象
          final BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
          // 获取图形上下文
          final Graphics2D graphics = (Graphics2D) image.getGraphics();
          // 设定背景颜色
          graphics.setColor(Color.WHITE); // ---1
          graphics.fillRect(0, 0, width, height);
          // 设定边框颜色
  //		graphics.setColor(getRandColor(100, 200)); // ---2
          graphics.drawRect(0, 0, width - 1, height - 1);
  
          final Random random = new Random();
          // 随机产生干扰线，使图象中的认证码不易被其它程序探测到
          for (int i = 0; i < count; i++) {
              graphics.setColor(getRandColor(150, 200)); // ---3
  
              final int x = random.nextInt(width - lineWidth - 1) + 1; // 保证画在边框之内
              final int y = random.nextInt(height - lineWidth - 1) + 1;
              final int xl = random.nextInt(lineWidth);
              final int yl = random.nextInt(lineWidth);
              graphics.drawLine(x, y, x + xl, y + yl);
          }
          // 取随机产生的认证码
          for (int i = 0; i < resultCode.length(); i++) {
              // 将认证码显示到图象中,调用函数出来的颜色相同，可能是因为种子太接近，所以只能直接生成
              // graphics.setColor(new Color(20 + random.nextInt(130), 20 + random
              // .nextInt(130), 20 + random.nextInt(130)));
              // 设置字体颜色
              graphics.setColor(Color.BLACK);
              // 设置字体样式
  //			graphics.setFont(new Font("Arial Black", Font.ITALIC, 18));
              graphics.setFont(new Font("Times New Roman", Font.BOLD, 24));
              // 设置字符，字符间距，上边距
              graphics.drawString(String.valueOf(resultCode.charAt(i)), (23 * i) + 8, 26);
          }
          // 图象生效
          graphics.dispose();
          return image;
      }
  
      private static Color getRandColor(int fc, int bc) { // 取得给定范围随机颜色
          final Random random = new Random();
          if (fc > 255) {
              fc = 255;
          }
          if (bc > 255) {
              bc = 255;
          }
  
          final int r = fc + random.nextInt(bc - fc);
          final int g = fc + random.nextInt(bc - fc);
          final int b = fc + random.nextInt(bc - fc);
  
          return new Color(r, g, b);
      }
  }
  