content: package jnpf.util;
  
  import javax.imageio.ImageIO;
  import javax.servlet.http.HttpServletResponse;
  import javax.servlet.http.HttpSession;
  import java.awt.*;
  import java.awt.image.BufferedImage;
  import java.util.Random;
  
  /**
   *
   * @author JNPF开发平台组
   * @version V3.1.0
   * @copyright 引迈信息技术有限公司
   * @date 2021/3/16 10:45
   */
  public class CodeUtil {
      /**
       *放到session中的key
       */
      public static final String RANDOMCODEKEY = "RANDOMCODEKEY";
      private Random random = new Random();
      /**
       *随机产生的字符串
       */
      private String randString = "abcdefghjklmnopqrstuvwxyz23456789ABCDEFGHJKLMNPQRSTUVWXYZ";
      /**
       *图片宽
       */
      private int width = 80;
      /**
       *图片高
       */
      private int height = 26;
      /**
       *干扰线数量
       */
      private int lineSize = 10;
      /**
       *随机产生字符数量
       */
      private int stringNum = 4;
  
      /**
       * 获得字体
       */
      private Font getFont(){
          return new Font("Fixedsys", Font.CENTER_BASELINE,18);
      }
  
      /**
       * 获得颜色
       */
      private Color getRandColor(int fc, int bc){
          if(fc > 255) {
              fc = 255;
          }
          if(bc > 255) {
              bc = 255;
          }
          int r = fc + random.nextInt(bc-fc-16);
          int g = fc + random.nextInt(bc-fc-14);
          int b = fc + random.nextInt(bc-fc-18);
          return new Color(r,g,b);
      }
  
      /**
       * 生成随机图片
       */
      public void getRandcode(HttpServletResponse response) {
          HttpSession session = ServletUtil.getSession();
          //BufferedImage类是具有缓冲区的Image类,Image类是用于描述图像信息的类
          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
          Graphics g = image.getGraphics();
          g.fillRect(0, 0, width, height);
          g.setFont(new Font("Times New Roman", Font.ROMAN_BASELINE,18));
          g.setColor(getRandColor(110, 133));
          //绘制干扰线
          for(int i=0;i<=lineSize;i++){
              drowLine(g);
          }
          //绘制随机字符
          String randomString = "";
          for(int i=1;i<=stringNum;i++){
              randomString=drowString(g,randomString,i);
          }
          session.removeAttribute(RANDOMCODEKEY);
          session.setAttribute(RANDOMCODEKEY, randomString);
          System.out.println("后台代码"+randomString);
          g.dispose();
          try {
              //将内存中的图片通过流动形式输出到客户端
              ImageIO.write(image, "JPEG", response.getOutputStream());
          } catch (Exception e) {
              e.printStackTrace();
          }
      }
  
      /**
       * 绘制字符串
       */
      private String drowString(Graphics g, String randomString, int i){
          g.setFont(getFont());
          g.setColor(new Color(random.nextInt(101),random.nextInt(111),random.nextInt(121)));
          String rand = String.valueOf(getRandomString(random.nextInt(randString.length())));
          randomString +=rand;
          g.translate(random.nextInt(3), random.nextInt(3));
          g.drawString(rand, 13*i, 16);
          return randomString;
      }
  
      /**
       * 绘制干扰线
       */
      private void drowLine(Graphics g){
          int x = random.nextInt(width);
          int y = random.nextInt(height);
          int xl = random.nextInt(13);
          int yl = random.nextInt(15);
          g.drawLine(x, y, x+xl, y+yl);
      }
  
      /**
       * 获取随机的字符
       */
      public String getRandomString(int num){
          return String.valueOf(randString.charAt(num));
      }
  }
  