java验证码生成类
package cn.edu.pdsu.action;import java.awt.Color;import java.awt.Font;import java.awt.Graphics;import java.awt.image.BufferedImage;import java.util.Random;import javax.imageio.ImageIO;import javax.servlet.ServletOutputStream;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.HttpSession;import org.apache.commons.lang.RandomStringUtils;import org.apache.struts2.ServletActionContext;/** * 类说明：验证码类（将验证码信息写入到session中 属性“authCode”） * * @author 作者: LiuJunGuang * @version 创建时间：2011-7-17 下午03:26:21 */public class AuthCodeAction {private HttpServletResponse response = ServletActionContext.getResponse();private HttpServletRequest request = ServletActionContext.getRequest();public String execute() {try {int width = 50;int height = 20;// 取得一个4位随机字母数字字符串String s = RandomStringUtils.random(4, true, true);// 保存入session,用于与用户的输入进行比较.// 注意比较完之后清除session.HttpSession session = request.getSession(true);session.setAttribute("authCode", s);response.setContentType("images/jpeg");//告知浏览器内容的类型response.setHeader("Pragma", "No-cache");//HTTP 1.0版 不要缓存response.setHeader("Cache-Control", "no-cache"); //HTTP 1.1 不要缓存response.setDateHeader("Expires", 0);//设置存活时间ServletOutputStream out = response.getOutputStream();//得到响应输出流BufferedImage image = new BufferedImage(width, height,BufferedImage.TYPE_INT_RGB);Graphics g = image.getGraphics();// 设定背景色g.setColor(getRandColor(200, 250));g.fillRect(0, 0, width, height);// 设定字体Font mFont = new Font("Times New Roman", Font.BOLD, 18);// 设置字体g.setFont(mFont);// 画边框// g.setColor(Color.BLACK);// g.drawRect(0, 0, width - 1, height - 1);// 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g.setColor(getRandColor(160, 200));// 生成随机类Random random = new Random();for (int i = 0; i < 125; i++) {int x2 = random.nextInt(width);int y2 = random.nextInt(height);int x3 = random.nextInt(12);int y3 = random.nextInt(12);g.drawLine(x2, y2, x2 + x3, y2 + y3);}// 绘制一些长的干扰线for (int i = 0; i < 5; i++) {int y1 = random.nextInt(15) + 3;g.drawLine(0, y1, width, y1);g.setColor(getRandColor(10, 160));}// 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)));g.drawString(s, 2, 16);// 图象生效g.dispose();// 输出图象到页面ImageIO.write((BufferedImage) image, "JPEG", out);//将图片以JPEG格式输出到out输出流中out.close();} catch (Exception e) {e.printStackTrace();}return null;}//获得某一范围的随机颜色private 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);}}