/*
* To change this template, choose Tools | Templates
* and open the template in the editor.
*/
package Action;
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import java.util.*;
import com.sun.image.codec.jpeg.*;
import java.awt.*;
import com.sun.image.codec.jpeg.*;
import java.awt.image.*;
import java.awt.geom.*;
import javax.swing.*;
import java.math.*;
import javax.imageio.ImageIO;
/**
*
* @author Administrator
*/
public class ValidateImgServletdds extends HttpServlet {
/**
* Processes requests for both HTTP <code>GET</code> and <code>POST</code> methods.
* @param request servlet request
* @param response servlet response
*/

@Override
public void service(HttpServletRequest request, HttpServletResponse response) throws
ServletException, IOException {
//更多资源请访问飞飞Asp技术乐园 www.ffasp.com
//本例来源：http://ffasp.com/content.asp?newsid=1107飞.飞Asp技术乐园
//设置页面不缓存
response.setContentType("image/jpeg");
response.setHeader("Pragma","No-cache");
response.setHeader("Cache-Control","no-cache");
response.setDateHeader("Expires", 0);

HttpSession session=request.getSession();


int width=60, height=20;
BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
// 获取图形上下文
Graphics g = image.getGraphics();
//生成随机类
Random random = new Random();
// 设定背景色
g.setColor(getRandColor(200,250));
g.fillRect(0, 0, width, height);
//设定字体
g.setFont(new Font("Times New Roman",Font.PLAIN,18));
// 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 = random.nextInt(width);
int y = random.nextInt(height);
int xl = random.nextInt(12);
int yl = random.nextInt(12);
g.drawLine(x,y,x+xl,y+yl);
}
// 取随机产生的认证码(4位数字)
String sRand="";
String string="0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
for (int i=0;i<4;i++){
String rand=String.valueOf(string.charAt(random.nextInt(string.length())));
sRand+=rand;
// 将认证码显示到图象
g.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.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?
g.drawString(rand,13*i+6,16);
}
// 将认证码存入SESSION
session.setAttribute("rand",sRand);

// 图象生效
g.dispose();
// 输出图象到页面

ImageIO.write(image, "JPEG", response.getOutputStream());

}

Color getRandColor(int fc,int bc){
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);
}
}
//更多资源请访问飞飞Asp技术乐园 www.ffasp.com飞飞A~sp技术乐园
//本例来源：http://ffasp.com/content.asp?newsid=1107飞飞Asp技术~乐园