content: package com.java2nb.common.utils;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import javax.imageio.ImageIO;
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpServletResponse;
  import javax.servlet.http.HttpSession;
  import java.awt.*;
  import java.awt.image.BufferedImage;
  import java.util.Random;
  
  /**
   * @author xiongxy
   */
  public class RandomValidateCodeUtil {
  
  
      public static final String RANDOMCODEKEY = "RANDOMVALIDATECODEKEY";//放到session中的key
      private String randString = "0123456789";//随机产生只有数字的字符串 private String
      //private String randString = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";//随机产生只有字母的字符串
      //private String randString = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";//随机产生数字与字母组合的字符串
      private int width = 95;// 图片宽
      private int height = 25;// 图片高
      private int lineSize = 40;// 干扰线数量
      private int stringNum = 4;// 随机产生字符数量
  
      private static final Logger logger = LoggerFactory.getLogger(RandomValidateCodeUtil.class);
  
      private Random random = new Random();
  
      /**
       * 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(HttpServletRequest request, HttpServletResponse response) {
          HttpSession session = request.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);
          Graphics g = image.getGraphics();// 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
          g.fillRect(0, 0, width, height);//图片大小
          g.setFont(new Font("Default", Font.ROMAN_BASELINE, 18));//字体大小
          g.setColor(getRandColor(110, 133));//字体颜色
          // 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);
          }
          logger.info(randomString);
          //将生成的随机字符串保存到session中
          session.removeAttribute(RANDOMCODEKEY);
          session.setAttribute(RANDOMCODEKEY, 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) {
              logger.error("将内存中的图片通过流动形式输出到客户端失败>>>> ", e);
          }
  
      }
  
      /**
       * 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));
      }
  }
  