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：
<"1.0" encoding="UTF-8"?> <web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list> <> <servlet> <> <servlet-name>Kaptcha</servlet-name> <servlet-class>com.google.code.kaptcha.servlet.KaptchaServlet</servlet-class> <> <init-param> <param-name>kaptcha.border</param-name> <param-value>no</param-value> </init-param> <> <init-param> <param-name>kaptcha.textproducer.font.color</param-name> <param-value>red</param-value> </init-param> <> <init-param> <param-name>kaptcha.image.width</param-name> <param-value>135</param-value> </init-param> <> <init-param> <param-name>kaptcha.textproducer.char.string</param-name> <param-value>ACDEFHKPRSTWX345679</param-value> </init-param> <> <init-param> <param-name>kaptcha.image.height</param-name> <param-value>50</param-value> </init-param> <> <init-param> <param-name>kaptcha.textproducer.font.size</param-name> <param-value>43</param-value> </init-param> <> <init-param> <param-name>kaptcha.noise.color</param-name> <param-value>black</param-value> </init-param> <> <init-param> <param-name>kaptcha.textproducer.char.length</param-name> <param-value>4</param-value> </init-param> <> <init-param> <param-name>kaptcha.textproducer.font.names</param-name> <param-value>Arial</param-value> </init-param> </servlet> <> <servlet-mapping> <servlet-name>Kaptcha</servlet-name> <url-pattern>/Kaptcha.jpg</url-pattern> </servlet-mapping> </web-app>
1.3、显示生成的验证码
在页面index.jsp显示验证码
<%@ page language="java" pageEncoding="UTF-8"%> <!DOCTYPE HTML> <html> <head> <title>显示KaptchaServlet生成的验证码</title> <script type="text/javascript" src="${pageContext.request.contextPath}/js/jquery-1.9.1.js"></script> <script type="text/javascript"> //点击切换验证码 function changeVerifyCode(){ $("#yzmImg").attr("src","Kaptcha.jpg"+Math.floor(Math.random()*100)); } //提交 function doSubmit() { var verifyCodeValue = $("#verifyCode").val(); if(verifyCodeValue.replace(/s/g,"") == "") { alert("请输入验证码"); }else { //提交前先异步检查验证码是否输入正确 var verifyUrl = "${pageContext.request.contextPath}/servlet/VerifyServlet"+verifyCodeValue; $.ajax({ type:"GET", url:verifyUrl, success:function(returnData){ if(returnData!="Y") { alert("请输入正确的验证码！"); }else { //验证码正确，进行提交操作 alert("验证码输入正确，提交表单"); } }, error:function(e){ alert(e); } }); } } </script> </head> <body> <form> <table> <tr> <td> 请输入验证码： </td> <td> <input type="text" name="verifyCode" id="verifyCode"> <img src="Kaptcha.jpg" id="yzmImg"> <a href="javascript:void(0)">看不清，换一张</a> </td> </tr> <tr> <td> </td> <td> <input type="button" value="提交"> </td> </tr> </table> </form> </body> </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：
/** * */ package me.gacl.web.controller; import java.io.IOException; import java.io.PrintWriter; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; public class VerifyServlet extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html;charaset=utf-8"); response.setHeader("pragma", "no-cache"); response.setHeader("cache-control", "no-cache"); PrintWriter out = null; try { //响应数据 String resultData; //获取传过来的验证码 String verifyCode = request.getParameter("verifyCode"); System.out.println("verifyCode----"+verifyCode); if(verifyCode=="") { resultData = "N"; }else { //获取kaptcha生成存放在session中的验证码 String kaptchaValue = (String) request.getSession().getAttribute(com.google.code.kaptcha.Constants.KAPTCHA_SESSION_KEY); //比较输入的验证码和实际生成的验证码是否相同 if(kaptchaValue == null || kaptchaValue == ""||!verifyCode.equalsIgnoreCase(kaptchaValue)) { resultData = "N"; }else { resultData = "Y"; } } out = response.getWriter(); out.write(resultData); out.flush(); }catch(Exception e) { e.printStackTrace(); }finally { if(out != null) { out.close(); } } } }
在web.xml中注册VerifyServlet
<> <servlet> <servlet-name>VerifyServlet</servlet-name> <servlet-class>me.gacl.web.controller.VerifyServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>VerifyServlet</servlet-name> <url-pattern>/servlet/VerifyServlet</url-pattern> </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，希望大家可以熟练掌握。