Java生成验证码

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package cn.net.seek.util;import java.awt.Color;import java.awt.Font;import java.awt.Graphics;import java.awt.image.BufferedImage;import java.io.IOException;import java.io.OutputStream;import java.util.Random;import javax.imageio.ImageIO;public class ImgZoom {// 验证码图片中可以出现的字符集,可根据需要修改private char mapTable[] = { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I','J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V','W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i','j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v','w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8','9' };/** * 生成验证码 * @param width 宽度  60 * @param height 高度  24 * @param os 输出流 * @return 生成的随机字符串 */public String getCertPic(int width, int height, OutputStream os) {BufferedImage image = new BufferedImage(width, height,BufferedImage.TYPE_INT_RGB);// 获取图形上下文Graphics g = image.getGraphics();// 生成随机类Random random = new Random();// 设定背景色// g.setColor(getRandColor(200, 250)); //随机生成背景色g.setColor(new Color(255, 255, 255));g.fillRect(0, 0, width, height);// 设定字体g.setFont(new Font("Times New Roman", Font.PLAIN, 18));// 随机产生155条干扰线,使图象中的认证码不易被其它程序探测到g.setColor(getRandColor(160, 200));for (int i = 0; i < 155; i++) {int x = random.nextInt(width);int y = random.nextInt(height);int xl = random.nextInt(12);int yl = random.nextInt(12);g.drawLine(x, y, x + xl, y + yl);}// 取随机产生的认证码(5位)String sRand = "";for (int i = 0; i < 5; i++) {String rand = mapTable[(int) (mapTable.length * Math.random())]+ "";sRand += rand;// 将认证码显示到图象中g.setColor(new Color(20 + random.nextInt(110), 20 + random.nextInt(110), 20 + random.nextInt(110)));// 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g.drawString(rand, 10 * i + 3, (int) (Math.random() * 9 + 14));// 14-23Math.round(Math.random()*(Max-Min)+Min)}// 释放图形上下文g.dispose();try {// 输出图象到页面ImageIO.write(image, "JPEG", os);} catch (IOException e) {return "";}return sRand;}Color getRandColor(int fc, int bc) {// 给定范围获得随机颜色Random random = new Random();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);}}