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How to implement verification code in ajax

php中世界最好的语言Original: 2018-03-30 17:16:142224browse

This time I will show you how to implement ajax verification code, and what are the precautions for ajax to implement verification code. The following is a practical case, let's take a look.

The example in this article shares the specific code for ajax to implement the verification code function for your reference. The specific content is as follows

First create a verification code:

<%@ page contentType="image/jpeg; charset=utf-8" 
  language="java" import="java.util.*,java.awt.*,java.awt.image.*,javax.imageio.*" 
  pageEncoding="UTF-8"%> 
<!-- 以上导入awt和awt.image包 --> 
<%! 
  //获取随机颜色 
  public Color getColor(){ 
   Random random = new Random(); 
   //使用rgb()随机产生颜色 
   int r = random.nextInt(256); 
   int g = random.nextInt(256); 
   int b = random.nextInt(256); 
    
   return new Color(r,g,b); 
  } 
   
  //获取随机数字 产生一个4位数 
  public String getNum(){ 
   String str = ""; 
   Random random = new Random(); 
   for(int i = 0;i < 4;i++){ 
    str += random.nextInt(10); //0-9 
   } 
   return str; 
  } 
%> 
 
<% 
  /* 清除缓存 */ 
  response.setHeader("pragma", "mo-cache"); 
  response.setHeader("cache-control", "no-cache"); 
  response.setDateHeader("expires", 0); 
  //产生矩形框 
  BufferedImage image = new BufferedImage(80,30,BufferedImage.TYPE_INT_RGB); 
  //获取画笔工具 
  Graphics g = image.getGraphics(); 
  //设置矩形框的颜色 
  g.setColor(new Color(200,200,200)); 
  //设置坐标和宽高 
  g.fillRect(0, 0, 80, 30); 
     
  //随机产生干扰线 
  for(int i = 0;i < 30;i++){ 
   Random random = new Random(); 
   int x = random.nextInt(80); 
   int y = random.nextInt(30); 
   int x1 = random.nextInt(x + 10); 
   int y1 = random.nextInt(y + 10); 
   //设置随机颜色 
   g.setColor(getColor()); 
   //画出来 
   g.drawLine(x, y, x1, y1); 
  } 
   
  //字的颜色和数字 
  g.setFont(new Font("Microsoft YaHei",Font.BOLD,16)); 
  g.setColor(Color.BLACK); 
  //获取随机数字 
  String checkNum = getNum(); 
   
  //给字拼接空格 
  StringBuffer sb = new StringBuffer(); 
  for(int i = 0;i < checkNum.length();i++){ 
   sb.append(checkNum.charAt(i) + " "); 
  } 
  //画出数字 
  g.drawString(sb.toString(), 15, 20); 
  //存入session域中 
  session.setAttribute("CHECKNUM", checkNum); //例如1010 
  //将图像以jpeg的形式通过字节流输出 
  ImageIO.write(image, "jpeg", response.getOutputStream()); 
  //清除缓存 
  out.clear(); 
  //放入body中 
  out = pageContext.pushBody(); 
%>

Put the verification code Compress it into an image, reference it in checkcode.jsp, and use ajax to send data to the server in this page

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%> 
<% 
String path = request.getContextPath(); 
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/"; 
%> 
 
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> 
<html> 
 <head> 
 <base href="<%=basePath%>" rel="external nofollow" > 
  
 <title>验证码</title> 
  
 <meta http-equiv="pragma" content="no-cache"> 
 <meta http-equiv="cache-control" content="no-cache"> 
 <meta http-equiv="expires" content="0">  
 <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"> 
 <meta http-equiv="description" content="This is my page"> 
 <style type="text/css"> 
  table{ 
   margin: 100px auto; 
  } 
   
 </style> 
 </head> 
 
 <body> 
  <table border="0" align="center"> 
   <tr> 
    <td>验证码</td> 
    <td><input type="text" name="checkcode" id="checkcodeID" maxlength="4" size="4"></td> 
    <td><img alt="加载失败" src="image.jsp"></td> 
    <td id="show">√√√</td> 
   </tr> 
  </table> 
 </body> 
 <script type="text/javascript"> 
  //去除空格 
  function trim(str){ 
   //从左侧开始替换空格 
   str = str.replace(/^\s*/,""); 
   //从左侧开始替换空格 
   str = str.replace(/\s$/,""); 
   return str; 
  } 
  
 </script> 
 
 <script type="text/javascript"> 
  //创建ajax对象 
  function createAjax(){ 
   var ajax = null; 
   try{ 
    ajax = new ActiveXObject("microsoft.xmlhttp"); 
   }catch(e){ 
    try{ 
     ajax = new XMLHttpRequest(); 
    }catch(e1){ 
     alert("请更换浏览器"); 
    } 
   } 
   return ajax; 
  } 
 </script> 
 
 
 <script type="text/javascript"> 
  document.getElementById("checkcodeID").onkeyup = function(){ 
   var checkcode = this.value; 
   //去除空格 
   checkcode = trim(checkcode); 
   if(checkcode.length == 4){ 
    //获取ajax对象 
    var ajax = createAjax(); 
    //获取去空格的内容 
     
    var method = "POST"; 
    var url = "${pageContext.request.contextPath}/CheckcodeServlet?time="+new Date().getTime(); 
    //准备发送异步请求 
    ajax.open(method, url); 
    //设置请求头POST提交方式才需要 
    ajax.setRequestHeader("content-type", "application/x-www-form-urlencoded"); 
    //拼接实体内容 
    var content = "checkcode=" + checkcode;     
    //发送请求 
    ajax.send(content); 
     
    //监听服务器状态变化 
    ajax.onreadystatechange = function(){ 
     if(ajax.readyState == 4){ 
      if(ajax.status == 200){ 
       //获取服务器内容 
       var tip = ajax.responseText; 
       //获取图片路径 然后进行放入td中 
       var img = document.createElement("img"); 
       img.src = tip; 
       img.style.width = "14px"; 
       img.style.height = "14px"; 
       var td = document.getElementById("show"); 
       td.innerHTML = ""; 
       td.appendChild(img); 
      } 
     } 
    } 
     
   } 
    
  } 
 </script> 
</html>

Then write the server to receive the input information, determine whether it matches the verification code, and add the corresponding The path of the image is output in the form of an output stream

public class CheckcodeServlet extends HttpServlet { 
 @Override 
 protected void doPost(HttpServletRequest req, HttpServletResponse resp) 
   throws ServletException, IOException { 
  req.setCharacterEncoding("utf-8"); 
  resp.setContentType("text/html;charset=utf-8"); 
  //图片路径 
  String tip = "images/MsgError.gif"; 
   
  String checkcode = req.getParameter("checkcode"); 
  //测试 
  System.out.println(checkcode); 
  //获取session域中的数字 
  String checkcodeService = (String) req.getSession().getAttribute("CHECKNUM"); 
  //判断 
  if (checkcode.equals(checkcodeService)) { 
   tip = "images/MsgSent.gif"; 
  } 
  //输出路径 
  PrintWriter pw = resp.getWriter(); 
  pw.write(tip); 
  pw.flush(); 
  pw.close(); 
 } 
}

When you enter the fourth number, a prompt will appear

Running result:

Believe it After reading the case in this article, you have mastered the method. For more exciting information, please pay attention to other related articles on the PHP Chinese website!

How to implement verification code in ajax

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