简单验证码实现(Ajax)

前端页面：

<!--验证码输入框 -->
<input type="text" class="entry" value="" placeholder="请输入短信验证码" id="u_code" autocomplete="off">
<!--获取验证码的按钮 -->
<input type="button" id="smsBtn" class="obtain" value="获取验证码" onclick="getRandNum(this);">
<!-- 服务器返回的验证码隐藏域 -->
<input type="hidden" name="randNum" id="randNum" value="" />

<a class="land" onclick="safeLogin()">确认登陆</a>

JS发送AJAX请求发送验证码：

获取到服务器响应后更新页面的隐藏域，在用户提交表单的时候可以此判断验证码是否输入正确。

 1 <script>
 2 var wait=0;
 3 
 4 function getRandNum(){ 
 5     var photo = "${safePhone }";
 6     var auId = "${auId }" ;
 7     //alert(photo);
 8     var xmlHttp = null;
 9     //表示当前浏览器不是ie,如ns,firefox
10     if(window.XMLHttpRequest) {
11         xmlHttp = new XMLHttpRequest();
12     } else if(window.ActiveXObject) {
13         xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
14     }
15     xmlHttp.onreadystatechange=function()
16     {
17     if (xmlHttp.readyState==4 && xmlHttp.status==200)
18       {
19           alert("验证码发送成功,请注意查收");
20           document.getElementById("randNum").value=xmlHttp.responseText;
21           wait=60;
22           var smsBtn = document.getElementById("smsBtn");
23           time(smsBtn);
24       }
25     }
26     xmlHttp.open("GET","${basePath }login/sendSmsCode.action?phone="+photo+"&auId="+auId,true);
27     xmlHttp.send();
28     
29 }
30 
31 //计时
32 function time(o) {    
33     if (wait == 0) {             
34         o.removeAttribute("disabled");    
35         //o.setAttribute("disabled", false);
36         o.value="获取验证码";
37          wait = 60;
38          document.getElementById("randNum").value="";
39     } else {
40         o.setAttribute("disabled", true);
41         o.value="已发(" + wait + "s)";
42         wait--;
43         setTimeout(function() {time(o)},1000);
44     }    
45 }
46 
47 function safeLogin(){
48     var u_code = document.getElementById("u_code").value;
49     var s_code = document.getElementById("randNum").value;
50     //alert(u_code);
51     if(u_code==""){
52         alert("验证码不能为空！");
53         return false ;
54     }
55     if(u_code!=s_code){
56         alert("验证码输入不正确，请输入正确验证码！");
57         return false ;
58     }
59     
60     var safeLoginFrm = document.getElementById("safeLoginFrm"); 
61     safeLoginFrm.submit();
62 }
63 
64 </script>

服务器端ACTION：

 1     /*
 2      * 发送短信验证码
 3      */
 4     public void sendSmsCode() {
 5         HttpServletResponse response = ServletActionContext.getResponse();
 6 
 7         // 产生6位随机数字
 8         Random r = new Random();
 9         String randNum = "";
10         for (int i = 0; i < 6; i++) {
11             randNum += r.nextInt(10);
12         }
13         String content = "【验证码】" + randNum + "(后台安全登陆验证码,一分钟内有效)";
14         // 发送短信begin：
15         Map<String, String> sendMap = SendSmsMessage
16                 .sendMessage(content, phone);
17         Integer sms_code = Integer.parseInt(sendMap.get("Code"));
18         String sms_result = sendMap.get("Result");
19         // 发送短信end
20 
21         try {
22             PrintWriter writer = response.getWriter();
23             writer.print(randNum);
24             writer.flush();
25             writer.close();
26         } catch (Exception e) {
27             e.printStackTrace();
28         }
29 
30     }