基于ajax实现验证码功能_AJAX相关-HTML5中文学习网

本文实例为大家分享了ajax实现验证码功能的具体代码，供大家参考，具体内容如下

首先创建一个验证码：

<%@ 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(); %>

将验证码压缩成图片，在checkcode.jsp中引用,并在该页面中利用ajax向服务器发送数据

<%@ 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>

然后编写服务端,接收输入的信息，判断是否与验证码相互匹配,将对应的图片的路径以输出流的方式输出

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();  } }

当输入第4个数字的时候就会出现提示
运行结果: