Generate verification code on jsp page

One: imageCode.jsp of the generated page

<%@ page contentType="image/jpeg" import="java.util.*,java.awt.*,java.io.*,java.awt.image.*,javax.imageio.*" pageEncoding="utf-8"%>
<%!
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(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);
}
%>
<%
//设置页面不缓存
response.setHeader("Pragma","No-cache");
response.setHeader("Cache-Control","no-cache");
response.setDateHeader("Expires", 0); int width=70, height=38;

// create image in memory

BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);

// Get graphics context
Graphics g = image.getGraphics();

//Generate random class
Random random = new Random();

//Set background color
g. setColor(getRandColor(200,250));
g.fillRect(0, 0, width, height);

//set the font
g.setFont(new Font("Times New Roman",Font.PLAIN,28));

//draw Border
//g.setColor(new Color());
//g.drawRect(0,0,width-1,height-1);

// Randomly generate 155 interference lines, so that the authentication code in the image is not easy to be read Other programs detected
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);
}

// Get the randomly generated authentication code (4 digits)
String sRand="";
for (int i=0;i<4;i++){
String rand=String.valueOf(random.nextInt(10));
sRand+=rand;
// Display the authentication code in the image
g.setColor(new Color(20+random .nextInt(110),20+random.nextInt(110),20+random.nextInt(110)));// The color from the calling function is the same, maybe because the seeds are too close, so only
g.drawString can be generated directly (rand,13*i+10,28);
}

// Save the authentication code into SESSION
session.setAttribute("rand",sRand);

// Image valid
g.dispose();
OutputStream output=response.getOutputStream( );

// output image to page
ImageIO.write(image, "JPEG", response.getOutputStream());
output.flush();
out.clear();
out = pageContext.pushBody();

2: Display of front-end login.jsp verification code

<img onclick="javascript:loadimage();" title="换一张试试" name="randImage" id="randImage" src="<%=initBasePath%>imageCode.jsp">

Three: Verify the picture switching event

Four: Verify

Get the verification code stored in the session in the background and compare the data in the verification code input box

Generate verification code on jsp page

Guess you like