CAS做单点登陆（SSO）——集成Java Web 项目

添加cas-client的jar包

下载cas-client，地址：http://www.ja-sig.org/downloads/cas-clients/，当前最新版本是cas-client-3.2.1-release.zip。然后解压cas-client-3.2.1-release.zip，在modules拷贝cas-client-core-3.2.1.jar到应用的WEB-INF/lib目录中。

撰写支持CAS集成的客户化包

除了在web.xml添加CAS内置的filter外（具体看配置web.xml），我们需要撰写自己支持CAS集成的客户化包。大致思路如下：

@Override
public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {

    HttpServletRequest request = (HttpServletRequest)servletRequest;
    HttpServletResponse response = (HttpServletResponse)servletResponse;

    HttpSession session = request.getSession();
    //在session中自定义一个参数，以它来校验是否完成过自动登陆
    Object user_login = session.getAttribute(AURORA_USER_LOGIN);
    if (user_login != null){
        //登陆过，就继续执行其他filter
        filterChain.doFilter(request, response);
        return;
    }
    //通过CAS的API获得登陆账号
    String loginName = AssertionHolder.getAssertion().getPrincipal().getName();
    try {
        //执行本系统的登陆。跟平常同时校验用户名和密码不同，这里只有用户名。
        executeLoginProc(request,response,loginName);
    } catch (Exception e) {
        logger.log(Level.SEVERE, "executeLoginProc error:", e);
        return;
    }
    //登陆成功
    session.setAttribute(AURORA_USER_LOGIN, Boolean.TRUE);
    //跳转到登陆成功后的页面
    response.sendRedirect(roleSelectPageUrl);
}

把这个class打包成一个jar拷贝到应用的WEB-INF/lib目录中。

如果有兴趣，还可以简单了解下org.jasig.cas.client.authentication.AuthenticationFilter这个CAS内置filter的功能

<p>public final void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
    HttpServletRequest request = (HttpServletRequest)servletRequest;
    HttpServletResponse response = (HttpServletResponse)servletResponse;
    HttpSession session = request.getSession(false);
 //检查自定义属性"_const_cas_assertion_"
    Assertion assertion = session != null ? (Assertion)session.getAttribute("_const_cas_assertion_") : null;</p><p>    if (assertion != null) {
      //已经成功登陆过CAS
      filterChain.doFilter(request, response);
      return;
    }
    //拿到url，并检查url参数中的ticket是否有效
    String serviceUrl = constructServiceUrl(request, response);
    String ticket = CommonUtils.safeGetParameter(request, getArtifactParameterName());
    boolean wasGatewayed = this.gatewayStorage.hasGatewayedAlready(request, serviceUrl);</p><p>    if ((CommonUtils.isNotBlank(ticket)) || (wasGatewayed)) {
      //ticket有效
      filterChain.doFilter(request, response);
      return;
    }</p><p>    this.log.debug("no ticket and no assertion found");
    String modifiedServiceUrl;
    String modifiedServiceUrl;
    if (this.gateway) {
      this.log.debug("setting gateway attribute in session");
      modifiedServiceUrl = this.gatewayStorage.storeGatewayInformation(request, serviceUrl);
    } else {
      modifiedServiceUrl = serviceUrl;
    }</p><p>    if (this.log.isDebugEnabled()) {
      this.log.debug("Constructed service url: " + modifiedServiceUrl);
    }</p><p>    String urlToRedirectTo = CommonUtils.constructRedirectUrl(this.casServerLoginUrl, getServiceParameterName(), modifiedServiceUrl, this.renew, this.gateway);</p><p>    if (this.log.isDebugEnabled()) {
      this.log.debug("redirecting to \"" + urlToRedirectTo + "\"");
    }
    //重定向到cas的登陆页面
    response.sendRedirect(urlToRedirectTo);
  }
</p>

 

修改web.xml

在应用WEB-INF/web.xml添加filter的内容，效果如下所示

<!-- ======================== 单点登录开始 ======================== -->
    <!-- 用于单点退出，该过滤器用于实现单点登出功能，可选配置-->
    <listener>
        <listener-class>org.jasig.cas.client.session.SingleSignOutHttpSessionListener</listener-class>
    </listener>

    <!-- 该过滤器用于实现单点登出功能，可选配置。 -->
    <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>

    <!-- 该过滤器负责用户的认证工作，必须启用它 -->
    <filter>
        <filter-name>CASFilter</filter-name>
        <filter-class>org.jasig.cas.client.authentication.AuthenticationFilter</filter-class>
        <init-param>
            <param-name>casServerLoginUrl</param-name>
            <param-value>https://sso.aurora-framework.org:8080/cas/login</param-value>
            <!--这里的server是服务端的IP-->
        </init-param>
        <init-param>
            <param-name>serverName</param-name>
            <param-value>https://sso.aurora-framework.org:8080</param-value>
        </init-param>
    </filter>
    <filter-mapping>
        <filter-name>CASFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>

    <!-- 该过滤器负责对Ticket的校验工作，必须启用它 -->
    <filter>
        <filter-name>CAS Validation Filter</filter-name>
        <filter-class>
            org.jasig.cas.client.validation.Cas20ProxyReceivingTicketValidationFilter</filter-class>
        <init-param>
            <param-name>casServerUrlPrefix</param-name>
            <param-value>https://sso.aurora-framework.org:8080/cas</param-value>
        </init-param>
        <init-param>
            <param-name>serverName</param-name>
            <param-value>https://sso.aurora-framework.org:8080</param-value>
        </init-param>
    </filter>
    <filter-mapping>
        <filter-name>CAS Validation Filter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>

    <!--
        该过滤器负责实现HttpServletRequest请求的包裹，
        比如允许开发者通过HttpServletRequest的getRemoteUser()方法获得SSO登录用户的登录名，可选配置。
    -->
    <filter>
        <filter-name>CAS HttpServletRequest Wrapper Filter</filter-name>
        <filter-class>
            org.jasig.cas.client.util.HttpServletRequestWrapperFilter</filter-class>
    </filter>
    <filter-mapping>
        <filter-name>CAS HttpServletRequest Wrapper Filter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>

    <!--
        该过滤器使得开发者可以通过org.jasig.cas.client.util.AssertionHolder来获取用户的登录名。
        比如AssertionHolder.getAssertion().getPrincipal().getName()。
    -->
    <filter>
        <filter-name>CAS Assertion Thread Local Filter</filter-name>
        <filter-class>org.jasig.cas.client.util.AssertionThreadLocalFilter</filter-class>
    </filter>
    <filter-mapping>
        <filter-name>CAS Assertion Thread Local Filter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>

    <!-- 自动根据单点登录的结果设置本系统的用户信息-->
    <filter>
        <display-name>AutoSetUserAdapterFilter</display-name>
        <filter-name>AutoSetUserAdapterFilter</filter-name>
        <filter-class>aurora.plugin.sso.cas.AutoSetUserFilter</filter-class>
        <init-param>
            <param-name>roleSelectPageUrl</param-name>
            <param-value>https://sso.aurora-framework.org:8080/yourapp/role_select.screen</param-value>
        </init-param>
    </filter>
    <filter-mapping>
        <filter-name>AutoSetUserAdapterFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>
    <!-- ======================== 单点登录结束 ======================== -->

 

前面几个都是CAS的标准配置，最后一个AutoSetUserAdapterFilter（自定义，可以取其他任意名字）才是我们支持cas的客户化程序。其中roleSelectPageUrl是指用户完成单点登录后跳转的页面。

本文档撰写时Java web项目和CAS用同一个tomcat，所以都用的https。否则只需要配置CAS的链接为HTTPS，本项目连接用HTTP。

 

修改CAS的认证逻辑

CAS默认的逻辑是用户名和密码一致就可以登陆，现在需要把原web系统的用户名和密码校验挪到CAS中。这里假设原先web系统中有一张sys_user表存储了用户名和MD5散列后的密码。

 

打开cas/WEB-INF/deployerConfigContext.xml

1. 注释掉SimpleTestUsernamePasswordAuthenticationHandler这个Handler，并添加

    

   <bean class="org.jasig.cas.adaptors.jdbc.QueryDatabaseAuthenticationHandler">
       <property ref="dataSource" name="dataSource"></property>
       <property name="sql" value="select t.encrypted_user_password from sys_user t where t.user_name=?"></property>
       <property ref="MD5PasswordEncoder" name="passwordEncoder"></property>
   </bean>

   
    

2.  在文件末尾之前加入数据库的链接：

   <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
       <property name="driverClassName">
           <value>oracle.jdbc.driver.OracleDriver</value>
       </property>
       <property name="url">
           <value>jdbc:oracle:thin:@yourIP:1521:yourOracleInstanceId</value>
       </property>
       <property name="username">
           <value>yourName</value>
       </property>
       <property name="password">
           <value>yourPassword</value>
       </property>
   </bean>
   <bean id="MD5PasswordEncoder" class="org.jasig.cas.authentication.handler.DefaultPasswordEncoder">
       <constructor-arg index="0">
           <value>MD5</value>
       </constructor-arg>
   </bean>

    

3. cas加入jdbc支持
   复制cas-server-3.5.2\modules\cas-server-support-jdbc-3.5.2.jar和Oracle驱动（这里采用oracle数据）的ojdbc14.jar或者classes12.jar放到cas/WEB-INF/lib目录下。

4. 重新登陆Web系统

   重启tomcat，在浏览器中输入https://sso.aurora-framework.org:8080/yourapp/，自动跳转到如下页面：

5. 输入web系统预先定义的用户名和密码，并跳转到自定义（web.xml中定义的）登陆成功后的页面。