彩色验证码

package test;//打包

//导入相关包import javax.servlet.*;import javax.servlet.http.*;import java.awt.*;import java.awt.image.*;import java.util.*;import javax.imageio.*;import java.io.*;

public class validate extends HttpServlet{

 public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException ,IOException {  response.setContentType("image/jpeg");  HttpSession session=request.getSession();  // 在内存中创建图象   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();     // 设定背景色   g.setColor(new Color(255,255,255));   g.fillRect(0, 0, width, height);     //画边框   g.setColor(Color.black);   g.drawRect(0,0,width-1,height-1);     // 取随机产生的认证码(4位数字)   Random now=new Random();  int xx=now.nextInt();  if(xx<0)  xx=0-xx;  String rand=xx+"";   switch(rand.length())   {   case 1: rand = "000"+rand; break;   case 2: rand = "00"+rand; break;   case 3: rand = "0"+rand; break;   default: rand = rand.substring(0,4); break;   }     // 将认证码存入SESSION   session.setAttribute("validate",rand);     // 将认证码显示到图象中   g.setColor(Color.black);   Integer tempNumber = new Integer(rand);   String numberStr = tempNumber.toString();     g.setFont(new Font("Atlantic Inline",Font.PLAIN,18));   String Str = numberStr.substring(0,1);   g.drawString(Str,8,17);     Str = numberStr.substring(1,2);   g.drawString(Str,20,15);   Str = numberStr.substring(2,3);   g.drawString(Str,35,18);     Str = numberStr.substring(3,4);   g.drawString(Str,45,15);     // 随机产生88个干扰点，使图象中的认证码不易被其它程序探测到   Random random = new Random();   for (int i=0;i<20;i++)   {   int x = random.nextInt(width);   int y = random.nextInt(height);   g.drawOval(x,y,0,0);   }     // 图象生效   g.dispose();     // 输出图象到页面   ImageIO.write(image, "JPEG", response.getOutputStream());     } 

 

  

 

}