cas添加验证码

转自：http://www.cnblogs.com/youngjoy/p/3217688.html

cas添加验证码，折腾了好久，终于整理好了，很大部分都是借鉴http://binghejinjun.iteye.com/blog/1255293这个的。但是他的有一个很不好的地方就是不能提升验证码错误！

红色字体的为我添加的，可以提示验证码错误！很简单，感谢。原作者。谢谢。

1.   首先,我用的cas版本是3.4.6,验证码采用的是CAPTCHA,所需jar包可以google搜索,部署好cas后.在web-info目录下找到login-webflow.xml,打开,找到如下代码: 

<view-state id= "viewLoginForm" view= "casLoginView" model= "credentials" > <var name= "credentials" class = "org.jasig.cas.authentication.principal.UsernamePasswordCredentials" /> <binder> <binding property= "username" /> <binding property= "password" /> </binder> <on-entry> <set name= "viewScope.commandName" value= "'credentials'" /> </on-entry> <transition on= "submit" bind= "true" validate= "true" to= "realSubmit" > <set name= "flowScope.credentials" value= "credentials" /> <evaluate expression= "authenticationViaFormAction.doBind(flowRequestContext, flowScope.credentials)" /> </transition> </view-state>

　　此段代码的功能是绑定cas登录过程中的用户名和密码,再次我们修改如下: 

<view-state id= "viewLoginForm" view= "casLoginView" model= "credentials" > <var name= "credentials" class = "org.jasig.cas.authentication.principal.UsernamePasswordCredentials" /> <binder> <binding property= "username" /> <binding property= "password" /> </binder> <on-entry> <set name= "viewScope.commandName" value= "'credentials'" /> </on-entry> <transition on= "submit" bind= "true" validate= "true" to= "yzmSubmit" > <set name= "flowScope.credentials" value= "credentials" /> <evaluate expression= "authenticationViaFormAction.doBind(flowRequestContext, flowScope.credentials)" /> </transition> </view-state>

　　也就是说,只需要修改realSubmit为yzmSubmit即可.然后加入如下配置: 

<!--fan add start--> 
<action-state id="yzmSubmit"> 
        <evaluate expression="yzmViaFormAction.submit(flowRequestContext，messageContext)" /> 
<transition on="success" to="realSubmit" /> 
<transition on="error" to="viewLoginForm" /> 
</action-state> 
<!--fan add end-->       

此段配置是自定义的验证码验证器,用来验证你提交的验证码的正确性. 

  2.在web-info下找到cas-servlet.xml,打开后,加入 

<!--fan add start--> <bean id= "yzmViaFormAction" class = "com.ivan.zhang.servlet.YzmAction" />

　　<!--fan add end-->此配置是注册自定义的验证码 

  3.编写如下类: 

package com.ivan.zhang.servlet; import com.ivan.zhang.CaptchaServiceSingleton; import com.octo.captcha.service.image.ImageCaptchaService; import java.io.PrintStream; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpSession; import org.jasig.cas.web.support.WebUtils; import org.springframework.webflow.core.collection.ParameterMap; import org.springframework.webflow.execution.RequestContext; public class YzmAction { public final String submit(RequestContext context) throws Exception { Boolean flag = Boolean.valueOf( false ); System.out.println( "YzmAction is submiting...................." ); String yzm = context.getRequestParameters().get( "yzm" ); String captchaId = WebUtils.getHttpServletRequest(context).getSession().getId(); flag = CaptchaServiceSingleton.getInstance().validateResponseForID(captchaId, yzm); if (flag.booleanValue()) { return "success" ; } <br> //<span style="background-color: #ff0000;">我添加的改动。提示验证码错误</span>

MessageBuilder msgBuilder = new MessageBuilder();

msgBuilder.defaultText("验证码错误！");

messageContext.addMessage(msgBuilder.error().build());

return "error" ; } }

　　其中,flag = CaptchaServiceSingleton.getInstance().validateResponseForID(captchaId, 

      yzm); 

此句话是为了验证提交的验证码和先前生成的验证码的正确性,以此作为验证结果跳转的依据.CaptchaServiceSingleton此类是自定义类,稍后会附加完整的类供下载调试. 

4.打开web-info/view/jsp/default/ui/casLoginView.jsp,在密码下面加入

<%--fan add start --%> <img alt= "yzm" src= "captcha.jpg" > <spring:message code= "screen.welcome.label.yzm.accesskey" var= "yzmAccessKey" /> <form:input cssClass= "required" cssErrorClass= "error" id= "yzm" size= "25" tabindex= "1" accesskey= "${yzmAccessKey}" path= "yzm" autocomplete= "false" htmlEscape= "true" /> <%--fan add end --%>

　　5. 最后一步则是注册验证码生成器,打开web.xml文件,加入 

<servlet>  <servlet-name>jcaptcha</servlet-name>  <servlet- class >com.ivan.zhang.servlet.ImageCaptchaServlet</servlet- class >  <load-on-startup> </load-on-startup>  </servlet> <servlet-mapping>  <servlet-name>jcaptcha</servlet-name>  <url-pattern>/captcha.jpg</url-pattern>  </servlet-mapping>

　　ok,就这么简单.简单解释一下流程,web.xml中注册的类是用来调用自定义的验证码生成器,以便在显示登陆界面的时候绘制验证码图片,并在session中生成标志位并记录,当用户提交验证码和用户名密码时,会先走自定义的验证码验证器(此时会先验证验证码的正确性),如果正确,再走用户名和密码的验证,如果不正确,则直接跳转回登陆页面.yzm.jar是自定义的验证码生成器和验证类,直接打包好后放到web-info/lib下. 

努力生活，珍惜一切，知足最快乐！young joy..