cas-client-autoconfig-support 2.3.0-GA使用教程及原理解析

cas-client-autoconfig-support是一个CAS客户端自动配置模块，它可以帮助开发人员快速地将Java Web应用程序集成到CAS单点登录系统中。

使用教程：

1. 下载cas-client-autoconfig-support的jar包并加入项目依赖中。

2. 在web.xml文件中添加如下配置：

<filter>
    <filter-name>CAS Single Sign Out Filter</filter-name>
    <filter-class>org.jasig.cas.client.session.SingleSignOutFilter</filter-class>
</filter>
<filter-mapping>
    <filter-name>CAS Single Sign Out Filter</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>
<filter>
    <filter-name>CAS Authentication Filter</filter-name>
    <filter-class>org.jasig.cas.client.authentication.AuthenticationFilter</filter-class>
    <init-param>
        <param-name>casServerLoginUrl</param-name>
        <param-value>https://cas.example.com/login</param-value>
    </init-param>
    <init-param>
        <param-name>serverName</param-name>
        <param-value>http://example.com</param-value>
    </init-param>
</filter>
<filter-mapping>
    <filter-name>CAS Authentication Filter</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>
<listener>
    <listener-class>org.jasig.cas.client.session.SingleSignOutHttpSessionListener</listener-class>
</listener>
<listener>
    <listener-class>org.jasig.cas.client.session.SingleSignOutHttpSessionListener</listener-class>
</listener>

其中，casServerLoginUrl参数是CAS服务器的登录地址，serverName参数是本应用程序的地址。

3. 在Spring配置文件中添加如下配置：

<bean class="org.jasig.cas.client.validation.Cas20ServiceTicketValidator">
    <constructor-arg index="0" value="https://cas.example.com" />
</bean>
<bean id="casAuthenticationEntryPoint" class="org.jasig.cas.client.authentication.CasAuthenticationEntryPoint">
    <property name="loginUrl" value="https://cas.example.com/login" />
    <property name="serviceProperties" ref="serviceProperties" />
</bean>
<bean id="serviceProperties" class="org.springframework.beans.factory.config.PropertiesFactoryBean">
    <property name="properties">
        <props>
            <prop key="service">http://example.com</prop>
        </props>
    </property>
</bean>
<bean id="casAuthenticationFilter" class="org.springframework.security.cas.web.CasAuthenticationFilter">
    <property name="authenticationManager" ref="authenticationManager" />
    <property name="authenticationSuccessHandler" ref="successHandler" />
</bean>
<bean id="successHandler" class="org.springframework.security.web.authentication.SavedRequestAwareAuthenticationSuccessHandler">
    <property name="defaultTargetUrl" value="/index.jsp" />
</bean>
<bean id="authenticationManager" class="org.springframework.security.authentication.ProviderManager">
    <property name="providers">
        <list>
            <ref local="casAuthenticationProvider" />
        </list>
    </property>
</bean>
<bean id="casAuthenticationProvider" class="org.springframework.security.cas.authentication.CasAuthenticationProvider">
    <property name="ticketValidator" ref="ticketValidator" />
    <property name="authenticationUserDetailsService" ref="authenticationUserDetailsService" />
    <property name="serviceProperties" ref="serviceProperties" />
    <property name="key" value="casAuthProviderKey" />
</bean>
<bean id="ticketValidator" class="org.jasig.cas.client.validation.Cas20ServiceTicketValidator">
    <constructor-arg index="0" value="https://cas.example.com" />
</bean>
<bean id="authenticationUserDetailsService" class="org.springframework.security.core.userdetails.UserDetailsByNameServiceWrapper">
    <constructor-arg ref="userDetailsService" />
</bean>
<bean id="userDetailsService" class="com.example.MyUserDetailsService" />

其中，casServerLoginUrl参数和serviceProperties的配置与web.xml中的相同，authenticationManager是Spring Security的认证管理器，authenticationUserDetailsService和userDetailsService是用户信息服务。

原理解析：

cas-client-autoconfig-support的原理是使用Java的反射机制，动态地加载CAS客户端的配置信息并注入到Java Web应用程序中。在web.xml文件中，CAS客户端的filter和listener是必须的，它们可以监听用户的会话状态并在用户退出登录时向CAS服务器发送注销请求。在Spring配置文件中，CAS客户端的认证过程是通过Spring Security框架实现的，它将CAS服务器返回的票据进行验证，并将用户信息封装成Spring Security认证对象。用户信息可以从数据库、LDAP等数据源中获取。