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);
}
}
