java验证码

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); } }