import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.sun.image.codec.jpeg.*;
/**
* 验证码图片生成Servlet类,直接调用该Servlet即可使用
* 取值的时候调用session.getAttribute("code")得到生成的值
* @author <a href="mailto:weijunqiang2010@gmail.com">Ajunboys</a>
*
*/
@WebServlet("/safecode")
public class SafeCodeImageServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
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 (fc < 0)
fc = 0;
if (bc > 255)
bc = 255;
if (bc < 0)
bc = 0;
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);
}
@Override
protected void service(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
// 设置输出
response.setContentType("image/jpeg");
int width = 80;
int height = 30;
// 产生随机数
Random r = new Random();
// 把随机数绘制成图像
BufferedImage imgbuf = new BufferedImage(width, height,
BufferedImage.TYPE_INT_RGB);// 产生缓冲图像,80宽30高
Graphics2D g = imgbuf.createGraphics();// 取得缓冲的绘制环境
// 开始绘制
g.setColor(getRandColor(200, 250));// 设定背景色
g.fillRect(0, 0, width, height);// 矩形图
// 随机产生155条干扰线,使图象中的认证码不易被其它程序探测到
g.setColor(getRandColor(160, 200));
for (int i = 0; i < 155; i++) {
int x = r.nextInt(width);
int y = r.nextInt(height);
int xl = r.nextInt(12);
int yl = r.nextInt(12);
g.drawLine(x, y, x + xl, y + yl);
}
g.setColor(getRandColor(120, 240));
// 随机产生100个干扰点,使图像中的验证码不易被其他分析程序探测到
for (int i = 0; i < 100; i++) {
int x = r.nextInt(width);
int y = r.nextInt(height);
g.drawOval(x, y, 0, 0);
}
g.setFont(new Font("Times New Roman", Font.PLAIN, 26));
String scode = "";
for (int i = 0; i < 4; i++) {
// String rand = String.valueOf(r.nextInt(10));
String rand = randomCode();
scode += rand;
g.setColor(new Color(20 + r.nextInt(110), 20 + r.nextInt(110),
20 + r.nextInt(110)));
// 调用函数出来的颜色相同,可能是因为种子太接近,所以只能直接生成
g.drawString(rand+" ", (0==i) ? 12 : (12 * (i+1)+5), 23);
}
request.getSession().setAttribute("safecode", scode);
// 输出图像
ServletOutputStream out = response.getOutputStream();// 得到HTTP的流
// JPEGCodec.createJPEGEncoder(out);转码
JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);// 产生JPEG的图像加码器
encoder.encode(imgbuf);
out.flush();
}
private static String randomCode(){
char[] dictionary = {
'2','3','4','5','6','7','8','9'
,'a','b','c','d','e','f','g','h','i','j'
,'k','m','n','p','q','r','s','t'
,'u','v','w','x','y','z'
,'A','B','C','D','E','F','G','H','J'
,'K','L','M','N','P','Q','R','S','T'
,'U','V','W','X','Y','Z'
/*'1','l','0','O','o','#','@','$','%','&','(',')','|','/','*'//暂时不用特殊字符(包括:数字1,0;字母:l,o,O)
,'^','!','~','\\'*/
};
StringBuffer code = new StringBuffer();
Random r = new Random();
code.append(dictionary[r.nextInt(dictionary.length)]);
return code.toString();
}
}