使用kaptcha生成验证码

  kaptcha是一个简单好用的验证码生成工具,通过配置,可以自己定义验证码大小、颜色、显示的字符等等。下面就来讲一下如何使用kaptcha生成验证码以及在服务器端取出验证码进行校验。

一、搭建测试环境

1.1、创建Web测试项目

  新建一个Web项目,并将kaptcha-2.3.2.jar放在项目的WEB-INF/lib目录下,如下图所示:

  

1.2、在web.xml文件配置生成验证码的KaptchaServlet

  KaptchaServlet的详细配置如下:

 1 xml version="1.0" encoding="UTF-8"?>
 2 <web-app version="2.5" 
 3     xmlns="http://java.sun.com/xml/ns/javaee" 
 4     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
 5     xsi:schemaLocation="http://java.sun.com/xml/ns/javaee 
 6     http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
 7   <welcome-file-list>
 8     <welcome-file>index.jspwelcome-file>
 9   welcome-file-list>
10   
11    
12     <servlet>
13         
14         <servlet-name>Kaptchaservlet-name>
15         <servlet-class>com.google.code.kaptcha.servlet.KaptchaServletservlet-class>
16         
17         
18         <init-param>
19             <param-name>kaptcha.borderparam-name>
20             <param-value>noparam-value>
21         init-param>    
22         
23         <init-param>
24             <param-name>kaptcha.textproducer.font.colorparam-name>
25             <param-value>redparam-value>
26         init-param>
27         
28         <init-param>
29             <param-name>kaptcha.image.widthparam-name>
30             <param-value>135param-value>
31         init-param>
32         
33         <init-param>
34             <param-name>kaptcha.textproducer.char.stringparam-name>
35             <param-value>ACDEFHKPRSTWX345679param-value>
36         init-param>
37         
38         <init-param>
39             <param-name>kaptcha.image.heightparam-name>
40             <param-value>50param-value>
41         init-param>
42         
43         <init-param>
44             <param-name>kaptcha.textproducer.font.sizeparam-name>
45             <param-value>43param-value>
46         init-param>
47         
48         <init-param>
49             <param-name>kaptcha.noise.colorparam-name>
50             <param-value>blackparam-value>
51         init-param>
52         
53         <init-param>
54             <param-name>kaptcha.textproducer.char.lengthparam-name>
55             <param-value>4param-value>
56         init-param>
57         
58         <init-param>
59             <param-name>kaptcha.textproducer.font.namesparam-name>
60             <param-value>Arialparam-value>
61         init-param>        
62     servlet>
63     
64     <servlet-mapping>
65         <servlet-name>Kaptchaservlet-name>
66         <url-pattern>/Kaptcha.jpgurl-pattern>
67     servlet-mapping>
68 web-app>

1.3、显示生成的验证码

  在页面index.jsp显示验证码

 1 <%@ page language="java" pageEncoding="UTF-8"%>
 2 DOCTYPE HTML>
 3 <html>
 4   <head>
 5     <title>显示KaptchaServlet生成的验证码title>
 6     <script type="text/javascript" src="${pageContext.request.contextPath}/js/jquery-1.9.1.js">script>
 7     <script type="text/javascript">
 8         //点击切换验证码
 9         function changeVerifyCode(){
10             $("#yzmImg").attr("src","Kaptcha.jpg?"+Math.floor(Math.random()*100));
11         }
12         
13         //提交
14         function doSubmit() {
15             var verifyCodeValue = $("#verifyCode").val();
16             if(verifyCodeValue.replace(/\s/g,"") == "") {
17                 alert("请输入验证码");
18             }else {
19                 //提交前先异步检查验证码是否输入正确
20                 var verifyUrl = "${pageContext.request.contextPath}/servlet/VerifyServlet?verifyCode="+verifyCodeValue;
21                 $.ajax({
22                     type:"GET",
23                     url:verifyUrl,
24                     success:function(returnData){
25                         if(returnData!="Y") {
26                             alert("请输入正确的验证码!");
27                         }else {
28                             //验证码正确,进行提交操作
29                             alert("验证码输入正确,提交表单");
30                         }
31                     },
32                     error:function(e){
33                         alert(e);
34                     }
35                 });
36             }
37         }
38     script>
39   head>
40   
41   <body>
42        <form>
43         <table>
44             <tr>
45                 <td>    
46                         请输入验证码:
47                 td>
48                 <td>
49                     <input type="text" name="verifyCode" id="verifyCode">
50                     <img src="Kaptcha.jpg" onclick="changeVerifyCode()" id="yzmImg" style="cursor: pointer;">
51                     <a href="javascript:void(0)" onclick="changeVerifyCode()">看不清,换一张a>
52                 td>
53             tr>
54             <tr>
55                 <td>    
56                      
57                 td>
58                 <td>
59                     <input type="button" value="提交" onclick="doSubmit()">
60                 td>
61             tr>
62         table>
63     form>    
64   body>
65 html>

  运行效果如下图所示:

  

1.4、在服务器端验证提交的验证码

  用户在form表单中提交了验证码之后,我们会在服务器端进行验证,编写一个VerifyServlet,代码如下:

 1 /**
 2  * 
 3  */
 4 package me.gacl.web.controller;
 5 
 6 import java.io.IOException;
 7 import java.io.PrintWriter;
 8 
 9 import javax.servlet.ServletException;
10 import javax.servlet.http.HttpServlet;
11 import javax.servlet.http.HttpServletRequest;
12 import javax.servlet.http.HttpServletResponse;
13 
14 public class VerifyServlet extends HttpServlet {
15 
16     
17     public void doGet(HttpServletRequest request, HttpServletResponse response)
18             throws ServletException, IOException {
19 
20         response.setContentType("text/html;charaset=utf-8");
21         response.setHeader("pragma", "no-cache");
22         response.setHeader("cache-control", "no-cache");
23         PrintWriter out = null;
24         try {
25             //响应数据
26             String resultData;
27             //获取传过来的验证码
28             String verifyCode = request.getParameter("verifyCode");
29             System.out.println("verifyCode----"+verifyCode);
30             if(verifyCode=="") {
31                 resultData = "N";
32             }else {
33                 //获取kaptcha生成存放在session中的验证码
34                 String kaptchaValue = (String) request.getSession().getAttribute(com.google.code.kaptcha.Constants.KAPTCHA_SESSION_KEY);
35                 //比较输入的验证码和实际生成的验证码是否相同
36                 if(kaptchaValue == null || kaptchaValue == ""||!verifyCode.equalsIgnoreCase(kaptchaValue)) {
37                     resultData = "N";
38                 }else {
39                     resultData = "Y";
40                 }
41             }
42             out = response.getWriter();
43             out.write(resultData);
44             out.flush();
45         }catch(Exception e) {
46             e.printStackTrace();
47         }finally {
48             if(out != null) {
49                 out.close();
50             }
51         }
52     }
53 }

  在web.xml中注册VerifyServlet

1 
2     <servlet>
3         <servlet-name>VerifyServletservlet-name>
4         <servlet-class>me.gacl.web.controller.VerifyServletservlet-class>
5     servlet>
6     <servlet-mapping>
7         <servlet-name>VerifyServletservlet-name>
8         <url-pattern>/servlet/VerifyServleturl-pattern>
9     servlet-mapping>

  运行结果如下:

  1、验证码不输入

  

  2、输入错误的验证码

  

  3、输入正确的验证码

  

  使用kaptcha生成验证码感觉挺不错的,非常好用和方便。

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