package work;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.*;
import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
public class checkcode extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
request.setCharacterEncoding("UTF-8");
response.setContentType("image/jpeg");
HttpSession session=request.getSession();
int width=60;
int height=20;
response.setHeader("Pragma","NO-cache");
response.setHeader("Cache-Control","no-cache");
response.setDateHeader("Expires",0);
BufferedImage image=new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);
Graphics g=image.getGraphics();
String chars="0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
char[] rands=new char[4];
for(int i=0;i<4;i++){
int rand=(int)(Math.random()*36);
rands[i]=chars.charAt(rand);
}
g.setColor(new Color(0xDCDCDC));
g.fillRect(0, 0, width, height);
for(int i=0;i<120;i++){
int x=(int)(Math.random()*width);
int y=(int)(Math.random()*height);
int red=(int)(Math.random()*255);
int green=(int)(Math.random()*255);
int blue=(int)(Math.random()*255);
g.setColor(new Color(red,green,blue));
g.drawOval(x, y, 1, 0);
}
g.setColor(Color.BLACK);
g.setFont(new Font(null,Font.ITALIC|Font.BOLD,18));
g.drawString(""+rands[0], 1, 17);
g.drawString(""+rands[1], 16, 15);
g.drawString(""+rands[2], 31, 18);
g.drawString(""+rands[3], 46, 16);
g.dispose();
ServletOutputStream sos=response.getOutputStream();
ByteArrayOutputStream baos=new ByteArrayOutputStream();
ImageIO.write(image, "JPEG", baos);
byte[] buffer=baos.toByteArray();
response.setContentLength(buffer.length);
sos.write(buffer);
baos.close();
sos.close();
session.setAttribute("checkcode", new String(rands));
}
}