验证码

package net.dbet.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.commons.lang.RandomStringUtils;
import org.apache.struts.action.Action;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionForward;
import org.apache.struts.action.ActionMapping;
/** 
* MyEclipse Struts
* 
* XDoclet definition:
* @struts.action validate="true"
*/
public class ImageAction 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);   
  }   
}