图片数字验证码

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileOutputStream;
import java.util.Random;

import javax.imageio.ImageIO;

import org.apache.log4j.Logger;
/**
* 验证码图片生成类
* @author Administrator
*
*/
public class CaptchaUtil {

private static final Logger LOGGER = Logger.getLogger(CaptchaUtil.class);

// 随机产生的字符串
private static final String RANDOM_STRS = "0123456789";

private static final String FONT_NAME = "Fixedsys";
private static final int FONT_SIZE = 18;

private Random random = new Random();

   private int width = 80;// 图片宽
   private int height = 25;// 图片高
   private int lineNum = 50;// 干扰线数量
   private int strNum = 4;// 随机产生字符数量

   /**
   * 生成随机图片
   */
   public BufferedImage genRandomCodeImage(StringBuffer randomCode) {
       // BufferedImage类是具有缓冲区的Image类
       BufferedImage image = new BufferedImage(width, height,
               BufferedImage.TYPE_INT_BGR);
       // 获取Graphics对象,便于对图像进行各种绘制操作
       Graphics g = image.getGraphics();
       // 设置背景色
       g.setColor(getRandColor(200, 250));
       g.fillRect(0, 0, width, height);

// 设置干扰线的颜色
g.setColor(getRandColor(110, 120));

       // 绘制干扰线
       for (int i = 0; i <= lineNum; i++) {
           drowLine(g);
       }
       // 绘制随机字符
       g.setFont(new Font(FONT_NAME, Font.ROMAN_BASELINE, FONT_SIZE));
       for (int i = 1; i <= strNum; i++) {
           randomCode.append(drowString(g, i));
       }
       g.dispose();
       return image;
   }

   /**
   * 给定范围获得随机颜色
   */
   private Color getRandColor(int fc, int bc) {
       if (fc > 255)
           fc = 255;
       if (bc > 255)
           bc = 255;
       int r = fc + random.nextInt(bc - fc);
       int g = fc + random.nextInt(bc - fc);
       int b = fc + random.nextInt(bc - fc);
       return new Color(r, g, b);
   }

   /**
   * 绘制字符串
   */
   private String drowString(Graphics g, int i) {
       g.setColor(new Color(random.nextInt(101), random.nextInt(111), random
               .nextInt(121)));
       String rand = String.valueOf(getRandomString(random.nextInt(RANDOM_STRS
               .length())));
       g.translate(random.nextInt(3), random.nextInt(3));
       g.drawString(rand, 13 * i, 16);
       return rand;
   }

   /**
   * 绘制干扰线
   */
   private void drowLine(Graphics g) {
       int x = random.nextInt(width);
       int y = random.nextInt(height);
       int x0 = random.nextInt(16);
       int y0 = random.nextInt(16);
       g.drawLine(x, y, x + x0, y + y0);
   }

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

   public static void main(String[] args) {
       CaptchaUtil tool = new CaptchaUtil();
       StringBuffer code = new StringBuffer();
       BufferedImage image = tool.genRandomCodeImage(code);
       System.out.println(">>> random code =: " + code);
       try {
           // 将内存中的图片通过流动形式输出到客户端
           ImageIO.write(image, "JPEG", new FileOutputStream(new File(
                   "random-code.jpg")));
       } catch (Exception e) {
           LOGGER.info("context", e);
       }

}
}

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