下面介绍用http协议使用cas单点登录系统。
一，前提条件
1，cas服务器部署测试成功。
2，下载cas-client-core-3.1.10.jar到你的应用lib目录下。
二，客户端配置（这里使用spring的方式来配置，spring本身的配置这里就不描述了）
1，配置web.xml文件，cas有4个filter需要配置，配置顺序不能改变，
<filter>
<filter-name>CAS Single Sign Out Filter</filter-name>
<filter-class>org.jasig.cas.client.session.SingleSignOutFilter</filter-class>
</filter>
<filter>
<filter-name>CAS Authentication Filter</filter-name>
<filter-class>org.springframework.web.filter.DelegatingFilterProxy</filter-class>
<init-param>
<param-name>targetBeanName</param-name>
<param-value>casAuthenticationFilter</param-value>
</init-param>
</filter>
<filter>
<filter-name>CAS Validation Filter</filter-name>
<filter-class>org.springframework.web.filter.DelegatingFilterProxy</filter-class>
<init-param>
<param-name>targetBeanName</param-name>
<param-value>casValidationFilter</param-value>
</init-param>
</filter>
<filter>
<filter-name>CAS HttpServletRequestWrapperFilter</filter-name>
<filter-class>org.springframework.web.filter.DelegatingFilterProxy</filter-class>
<init-param>
<param-name>targetBeanName</param-name>
<param-value>casHttpServletRequestWrapperFilter</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>CAS Single Sign Out Filter</filter-name>
<url-pattern>*.do</url-pattern>
</filter-mapping>
<filter-mapping>
<filter-name>CAS Authentication Filter</filter-name>
<url-pattern>*.do</url-pattern>
</filter-mapping>
<filter-mapping>
<filter-name>CAS Validation Filter</filter-name>
<url-pattern>*.do</url-pattern>
</filter-mapping>
<filter-mapping>
<filter-name>CAS HttpServletRequestWrapperFilter</filter-name>
<url-pattern>*.do</url-pattern>
</filter-mapping>
2，spring文件的配置，新增一个spring配置文件，文件名随意，我这里叫做applicationContext-cas.xml，文件内容为
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p"
xmlns:aop="http://www.springframework.org/schema/aop" xmlns:tx="http://www.springframework.org/schema/tx"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:jee="http://www.springframework.org/schema/jee" xmlns:util="http://www.springframework.org/schema/util"
xsi:schemaLocation="http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.0.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.0.xsd http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee-3.0.xsd http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-3.0.xsd"
default-autowire="byName" default-lazy-init="false">
<bean id="casAuthenticationFilter"
class="org.jasig.cas.client.authentication.AuthenticationFilter">
<property name="casServerLoginUrl" value="${cas.url}/login" />
<property name="serverName" value="${project.url}" />
<property name="renew" value="false" />
<property name="gateway" value="false" />
</bean>
<bean id="casValidationFilter"
class="org.jasig.cas.client.validation.Cas20ProxyReceivingTicketValidationFilter">
<property name="ticketValidator">
<ref bean="Cas20ServiceTicketValidator" />
</property>
<property name="useSession" value="true" />
<property name="serverName" value="${project.url}" />
<property name="redirectAfterValidation" value="true" />
</bean>
<bean id="Cas20ServiceTicketValidator"
class="org.jasig.cas.client.validation.Cas20ServiceTicketValidator">
<constructor-arg index="0" value="${cas.url}" />
</bean>
<bean id="casHttpServletRequestWrapperFilter"
class="org.jasig.cas.client.util.HttpServletRequestWrapperFilter" />
</beans>
上面红色部分的意思是： cas.url是你cas服务器的地址，project.url是你客户端应用的地址。下面是我本地的配置
#cas服务器地址
cas.url=http://127.0.0.1:8080/cas
#客户端url地址
project.url=http://127.0.0.1:8080
3，客户端数据库的配置
建议cas服务器和客户端公用同一个数据库，如果分开，就会涉及到数据同步问题。