Of Stack

Local Refresh Verification Code for jsp+ajax Event Trigger Verification of onblur

  • 2021-09-05 00:37:34
  • OfStack

In this paper, the local refresh check verification code implemented by jsp+ajax (onblur event triggers check) is described as an example. Share it for your reference, as follows:

Foreground display page:

welcome.jsp 


<%@ page language="java" contentType="text/html; utf-8" 
 pageEncoding="utf-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title> Modify personal information </title>
<script>
function createXMLHttpRequest() {
 // Indicates that the current browser is not ie, Such as ns,firefox
 if(window.XMLHttpRequest) {
  xmlHttp = new XMLHttpRequest();
 } else if (window.ActiveXObject) {
  xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
 }
}
function validate(field) {
 var div=document.getElementById("divbid");
// var reg=/[^A-Za-z0-9_]{7,10}/g;
 if (field.value.length != 0) {
  // Create XMLHttpRequest
  createXMLHttpRequest();
  var url = "codevalidate.jsp?authcode=" + field.value + " × tamp=" + new Date().getTime();// Timestamping to prevent cache duplication 
  xmlHttp.open("GET", url, true);
  // Method address, automatically called after processing, callback 
  xmlHttp.onreadystatechange=function() { // Anonymous function 
   if(xmlHttp.readyState == 4) { //Ajax Engine initialization successful 
    if (xmlHttp.status == 200) { //http Agreement Successful 
     document.getElementById("divbid").innerHTML =xmlHttp.responseText;
    }else {
     alert(" Request failed, error code =" + xmlHttp.status);
    }
   }
  };
  // Send parameters to the Ajax Engine 
  xmlHttp.send(null);
 }else {
   div.innerHTML="<div class=\"wrong\"> Verification code cannot be empty </div>"
 }
}
function reloadImage(imgurl){
 var getimagecode=document.getElementById("codeimg");
 getimagecode.src= imgurl + "?id=" + Math.random();
  var code=<%=session.getAttribute("code")%>;
  alert(code)
}
</script>
</head>
<body>
<form action="authcode.jsp" method="post" name="loginform">
   Enter verification code: <input type="text" name="authcode" id="authcode" maxlength="4" size="10" onblur="validate(this)" ><span id="divbid"></span>
  <img id="codeimg" name="codeimg" border=0 src="authcode.jsp">
  <a href="javascript:reloadImage('authcode.jsp')"> Can't see clearly </a><br/>
</form>
<script language="javascript" type="text/javascript">
function reloadImage(imgurl){
 var getimagecode=document.getElementById("codeimg");
 getimagecode.src= imgurl + "?id=" + Math.random();
 var code=<%=session.getAttribute("code")%>;
 alert(code)
}
</script>
</body>
</html>

Generate a picture page

authcode.jsp 


<%@ page contentType="image/JPEG" 
 import="java.awt.*,java.awt.image.*,java.util.*,javax.imageio.*" 
 pageEncoding="GBK"%> 
<%!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 < 100; 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 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);  
  System.out.println(rand); 
 }  
 //  Save the authentication code in SESSION  
 session.setAttribute("code", sRand);  
 //  Image validation   
 g.dispose();  
 //  Output image to page   
 ImageIO.write(image, "JPEG", response.getOutputStream());  
%>

ajax Dynamic Validation Page

codevalidate.jsp 


<%@ page language="java" import="java.util.*,java.util.*,java.text.*,com.neusoft.xkxt.dao.*,com.neusoft.xkxt.bean.*,com.neusoft.xkxt.util.*" pageEncoding="UTF-8"%> 
<% 
String path = request.getContextPath(); 
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/"; 
%> 
<% 
 String authcode=request.getParameter("authcode"); 
 String code=(String)session.getAttribute("code"); 
 if(authcode.equals(code)){ 
 out.println("<div class='right'> Tick </div>");} 
 else{ 
 out.println("<div class='wrong'> Incorrect verification code </div>");} 
%>

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

Related articles: