A Simple Method for Generating JSP Verification Code

This paper describes a simple generation method of JSP verification code with an example. Share it for your reference. The details are as follows:

<%@ page contentType="image/jpeg" import="java.awt.*,java.awt.image.*,java.util.*,javax.imageio.*" %>
<%!
Color getRandColor(int fc,int bc){// Get random colors in a given range 
    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);
    }
%>
<%
// Setting the page not to cache 
response.setHeader("Pragma","No-cache");
response.setHeader("Cache-Control","no-cache");
response.setDateHeader("Expires", 0);
//  Create an image in memory 
int width=60, height=20;
BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
//  Getting Graphics Context 
Graphics g = image.getGraphics();
// Generate random classes 
Random random = new Random();
//  Set the background color 
g.setColor(getRandColor(200,250));
g.fillRect(0, 0, width, height);
// Set fonts 
g.setFont(new Font("Times New Roman",Font.PLAIN,18));
// Draw a border 
//g.setColor(new Color());
//g.drawRect(0,0,width-1,height-1);
//  Random generation 155 Interference lines, so that the authentication code in the image is not easy to be detected by other programs 
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);
}
//  Randomly generated authentication codes are taken (4 Bit number )
//String rand = request.getParameter("rand");
//rand = rand.substring(0,rand.indexOf("."));
String sRand="";
for (int i=0;i<4;i++){
  String rand=String.valueOf(random.nextInt(10));
  sRand+=rand;
  //  Display the authentication code to the image 
  g.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110)));// The color of the calling function is the same, which may be because the seeds are too close, so it can only be generated directly 
  g.drawString(rand,13*i+6,16);
}
//  Save the authentication code in SESSION
session.setAttribute("rand",sRand);
//  Image validation 
g.dispose();
//  Output image to page 
ImageIO.write(image, "JPEG", response.getOutputStream());
out.clear();
out = pageContext.pushBody();
%>

I hope this article is helpful to everyone's JSP programming.