最近博客园的改版动作比较大，看到后台管理页面的验证码，提起了我的兴趣。点击显示的验证码，可以进入到一个专门做验证码的网站：http://captcha.com/
其中包含有java、php、.net等，几乎是全平台支持的，还有配套的教程和demo。
文末提供下载下来的java版的文件，里面有jar包，如何使用呢？想快速入手：
一：最简单的文字验证码。使用jsp方式。
在jsp页面引用：
<%@page import="botdetect.web.Captcha"%>
然后在需要验证码的地方加上:
<% // Adding BotDetect Captcha to the page Captcha captcha = Captcha.load(request, "exampleCaptcha"); captcha.renderCaptchaMarkup(pageContext.getServletContext(), pageContext.getOut()); %> <input id="captchaCodeTextBox" type="text" name="captchaCodeTextBox" />
检测用户输入的验证码是否正确
<% if("POST".equalsIgnoreCase(request.getMethod())){ // validate the Captcha to check we're not dealing with a bot boolean isHuman = captcha.validate(request, request.getParameter("captchaCodeTextBox")); if(isHuman){ // TODO: Captcha validation passed, perform protected action } else { // TODO: Captcha validation failed, show error message } } %>
既然引入了第三方jar包，当然少不了在web.xml中配置了。
<servlet-name>BotDetect Captcha</servlet-name>
<servlet-class>botdetect.web.http.CaptchaServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>BotDetect Captcha</servlet-name>
<url-pattern>/botdetectcaptcha</url-pattern>
</servlet-mapping>
二：使用SpringMVC方式。
对应的页面：
<%@page contentType="text/html" pageEncoding="UTF-8"%>
<%@taglib prefix="botDetect" uri="botDetect"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>BotDetect CAPTCHA Spring MVC Basic Example</title>
<link rel="stylesheet" href="stylesheet.css" type="text/css"/>
</head>
<body>
<form method="post">
<h1>BotDetect CAPTCHA Spring MVC Basic Example</h1>
<fieldset>
<legend>CAPTCHA Validation</legend>
<label for="captchaCodeTextBox" class="prompt">
Retype the code from the picture:</label>
<!-- Adding BotDetect Captcha to the page -->
<botDetect:captcha id="basicExampleCaptcha"/>
<div class="validationDiv">
<input id="captchaCodeTextBox" type="text"
name="captchaCodeTextBox"
value="${basicExample.captchaCodeTextBox}"/>
<input type="submit" name="submit" value="Submit" />
<span class="correct">${basicExample.captchaCodeCorrect}</span>
<span class="incorrect">${basicExample.captchaCodeIncorrect}</span>
</div>
</fieldset>
</form>
</body>
</html>
页面对应的controller：
package botdetect.examples.springmvc.basic.controller; import botdetect.examples.springmvc.basic.model.BasicExample; import botdetect.web.Captcha; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.springframework.validation.BindException; import org.springframework.web.servlet.ModelAndView; import org.springframework.web.servlet.mvc.SimpleFormController; public class IndexController extends SimpleFormController { public IndexController(){ setCommandClass(BasicExample.class); } @Override protected ModelAndView onSubmit(HttpServletRequest request, HttpServletResponse response, Object command, BindException errors){ BasicExample basicExample = (BasicExample)command; // validate the Captcha to check we're not dealing with a bot Captcha captcha = Captcha.load(request, "basicExampleCaptcha"); boolean isHuman = captcha.validate(request, basicExample.getCaptchaCodeTextBox()); if (isHuman) { basicExample.setCaptchaCodeCorrect("Correct."); basicExample.setCaptchaCodeIncorrect(""); } else { basicExample.setCaptchaCodeCorrect(""); basicExample.setCaptchaCodeIncorrect("Incorrect!"); } basicExample.setCaptchaCodeTextBox(""); return new ModelAndView("index", "basicExample", basicExample); } }
验证码对应的bean
package botdetect.examples.springmvc.basic.model; public class BasicExample { private String userCaptchaCode, captchaCodeCorrect, captchaCodeIncorrect; public String getCaptchaCodeTextBox() { return userCaptchaCode; } public void setCaptchaCodeTextBox(String userCaptchaCode) { this.userCaptchaCode = userCaptchaCode; } public String getCaptchaCodeCorrect() { return captchaCodeCorrect; } public void setCaptchaCodeCorrect(String captchaCodeCorrect) { this.captchaCodeCorrect = captchaCodeCorrect; } public String getCaptchaCodeIncorrect() { return captchaCodeIncorrect; } public void setCaptchaCodeIncorrect(String captchaCodeIncorrect) { this.captchaCodeIncorrect = captchaCodeIncorrect; } }
下载验证码文件：
http://captcha.com/botdetect-java-captcha-component-free.zip