java验证码

1package cn.edu.pdsu.action;
2
3import java.awt.Color;
4import java.awt.Font;
5import java.awt.Graphics;
6import java.awt.image.BufferedImage;
7import java.util.Random;
8
9import javax.imageio.ImageIO;
10import javax.servlet.ServletOutputStream;
11import javax.servlet.http.HttpServletRequest;
12import javax.servlet.http.HttpServletResponse;
13import javax.servlet.http.HttpSession;
14
15import org.apache.commons.lang.RandomStringUtils;
16import org.apache.struts2.ServletActionContext;
17
18/**
19 * 类说明：验证码类（将验证码信息写入到session中 属性“authCode”）
20 * 
21 * @author 作者: LiuJunGuang
22 * @version 创建时间：2011-7-17 下午03:26:21
23 */
24public class AuthCodeAction {
25	private HttpServletResponse response = ServletActionContext.getResponse();
26	private HttpServletRequest request = ServletActionContext.getRequest();
27
28	public String execute() {
29		try {
30			int width = 50;
31			int height = 20;
32			// 取得一个4位随机字母数字字符串
33			String s = RandomStringUtils.random(4, true, true);
34
35			// 保存入session,用于与用户的输入进行比较.
36			// 注意比较完之后清除session.
37			HttpSession session = request.getSession(true);
38			session.setAttribute("authCode", s);
39
40			response.setContentType("images/jpeg");//告知浏览器内容的类型
41			response.setHeader("Pragma", "No-cache");//HTTP 1.0版 不要缓存
42			response.setHeader("Cache-Control", "no-cache"); //HTTP 1.1  不要缓存
43			response.setDateHeader("Expires", 0);//设置存活时间
44
45			ServletOutputStream out = response.getOutputStream();//得到响应输出流
46			BufferedImage image = new BufferedImage(width, height,
47					BufferedImage.TYPE_INT_RGB);
48			Graphics g = image.getGraphics();
49			// 设定背景色
50			g.setColor(getRandColor(200, 250));
51			g.fillRect(0, 0, width, height);
52
53			// 设定字体
54			Font mFont = new Font("Times New Roman", Font.BOLD, 18);// 设置字体
55			g.setFont(mFont);
56
57			// 画边框
58			// g.setColor(Color.BLACK);
59			// g.drawRect(0, 0, width - 1, height - 1);
60
61			// 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
62			g.setColor(getRandColor(160, 200));
63			// 生成随机类
64			Random random = new Random();
65			for (int i = 0; i < 125; i++) {
66				int x2 = random.nextInt(width);
67				int y2 = random.nextInt(height);
68				int x3 = random.nextInt(12);
69				int y3 = random.nextInt(12);
70				g.drawLine(x2, y2, x2 + x3, y2 + y3);
71			}
72			// 绘制一些长的干扰线
73			for (int i = 0; i < 5; i++) {
74				int y1 = random.nextInt(15) + 3;
75				g.drawLine(0, y1, width, y1);
76				g.setColor(getRandColor(10, 160));
77			}
78
79			// 将认证码显示到图象中
80			g.setColor(new Color(20 + random.nextInt(110), 20 + random
81					.nextInt(110), 20 + random.nextInt(110)));
82
83			g.drawString(s, 2, 16);
84
85			// 图象生效
86			g.dispose();
87			// 输出图象到页面
88			ImageIO.write((BufferedImage) image, "JPEG", out);//将图片以JPEG格式输出到out输出流中
89			out.close();
90		} catch (Exception e) {
91			e.printStackTrace();
92		}
93		return null;
94	}
95
96	//获得某一范围的随机颜色
97	private Color getRandColor(int fc, int bc) { // 给定范围获得随机颜色
98		Random random = new Random();
99		if (fc > 255)
100			fc = 255;
101		if (bc > 255)
102			bc = 255;
103		int r = fc + random.nextInt(bc - fc);
104		int g = fc + random.nextInt(bc - fc);
105		int b = fc + random.nextInt(bc - fc);
106		return new Color(r, g, b);
107	}
108}