struts中的图片验证

package cn.com.lough.struts.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.struts.action.Action;   
import org.apache.struts.action.ActionForm;   
import org.apache.struts.action.ActionForward;   
import org.apache.struts.action.ActionMapping;   
import org.apache.commons.lang.RandomStringUtils;   
  
/**  
* MyEclipse Struts Creation date: 01-11-2007  
*   
* XDoclet definition:  
*   
* @struts.action validate="true"  
*/  
public class ValidatecodeAction extends Action {   
    /*  
     * Generated Methods  
     */  
  
    /**  
     * Method execute  
     *   
     * @param mapping  
     * @param form  
     * @param request  
     * @param response  
     * @return ActionForward  
     */  
    public ActionForward execute(ActionMapping mapping, ActionForm form,   
            HttpServletRequest request, HttpServletResponse response) {   
        try {   
            int width = 50;   
            int height = 18;   
            // 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("validateCode", s);   
  
            response.setContentType("images/jpeg");   
            response.setHeader("Pragma", "No-cache");   
            response.setHeader("Cache-Control", "no-cache");   
            response.setDateHeader("Expires", 0);   
  
            ServletOutputStream out = response.getOutputStream();   
            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 < 155; 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);   
            }   
  
            // 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);   
            out.close();   
        } catch (Exception e) {   
            e.printStackTrace();   
        }   
        return null;   
    }   
  
    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);   
    }   
}   
  
  
jsp页面的调用    
<html:img page="/validatecode.do" border="0" onclick="this.src='/validatecode.do'" alt="请输入此验证码，如看不清请点击刷新。" style="cursor:pointer" />