在配置cas支持客户端自定义页面时报...报错

配置时，参考网上的，先是配置web.xml，

如下：<listener>
<listener-class>org.jasig.cas.client.session.SingleSignOutHttpSessionListener</listener-class>
</listener>
<!-- CAS -->
<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 Filter</filter-name>
<filter-class>com.cas.client.validation.RemoteAuthenticationFilter</filter-class>
<init-param>
<param-name>localLoginUrl</param-name>
<param-value>http://localhost:8080/casclient</param-value>
</init-param>
<init-param>
<param-name>casServerLoginUrl</param-name>
<param-value>https://localhost:8443/cas-server/remoteLogin</param-value>
</init-param>
<init-param>
<param-name>edu.yale.its.tp.cas.client.filter.validateUrl</param-name>
<param-value>https://localhost:8443/cas-server/serviceValidate</param-value>
</init-param>
<init-param>   
            <param-name>edu.yale.its.tp.cas.client.filter.serverName</param-name>  
            <param-value>http://localhost:8080</param-value>  
  </init-param>  
</filter>


<filter-mapping>
<filter-name>CAS Single Sign Out Filter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
<filter-mapping>
<filter-name>CAS Filter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>

而后，编写com.cas.client.validation.RemoteAuthenticationFilter，其如下：

package com.cas.client.validation;


import java.io.IOException;
import java.net.URL;
import java.net.URLEncoder;


import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;


import org.jasig.cas.client.util.AbstractCasFilter;
import org.jasig.cas.client.util.CommonUtils;
import org.jasig.cas.client.validation.Assertion;


public class RemoteAuthenticationFilter extends AbstractCasFilter {
    
    public static final String CONST_CAS_GATEWAY = "_const_cas_gateway_";


    /**
     * 本地登陆页面URL.
     */
    private String localLoginUrl;
    
    /**
     * The URL to the CAS Server login.
     */
    private String casServerLoginUrl;


    /**
     * Whether to send the renew request or not.
     */
    private boolean renew = false;


    /**
     * Whether to send the gateway request or not.
     */
    private boolean gateway = false;


    protected void initInternal(final FilterConfig filterConfig) throws ServletException {
        super.initInternal(filterConfig);
        setCasServerLoginUrl(getPropertyFromInitParams(filterConfig, "casServerLoginUrl", null));
        log.trace("Loaded CasServerLoginUrl parameter: " + this.casServerLoginUrl);
        setLocalLoginUrl(getPropertyFromInitParams(filterConfig, "localLoginUrl", null));
        log.trace("Loaded LocalLoginUrl parameter: " + this.localLoginUrl);
        setRenew(Boolean.parseBoolean(getPropertyFromInitParams(filterConfig, "renew", "false")));
        log.trace("Loaded renew parameter: " + this.renew);
        setGateway(Boolean.parseBoolean(getPropertyFromInitParams(filterConfig, "gateway", "false")));
        log.trace("Loaded gateway parameter: " + this.gateway);
    }


    public void init() {
        super.init();
        CommonUtils.assertNotNull(this.localLoginUrl, "localLoginUrl cannot be null.");
        CommonUtils.assertNotNull(this.casServerLoginUrl, "casServerLoginUrl cannot be null.");
    }


    public final void doFilter(final ServletRequest servletRequest,
            final ServletResponse servletResponse, final FilterChain filterChain)
            throws IOException, ServletException {
        final HttpServletRequest request = (HttpServletRequest) servletRequest;
        final HttpServletResponse response = (HttpServletResponse) servletResponse;
        final HttpSession session = request.getSession(false);
        final String ticket = request.getParameter(getArtifactParameterName());
        final Assertion assertion = session != null ? (Assertion) session
                .getAttribute(CONST_CAS_ASSERTION) : null;
        final boolean wasGatewayed = session != null
                && session.getAttribute(CONST_CAS_GATEWAY) != null;


        // 如果访问路径为localLoginUrl且带有validated参数则跳过
        URL url = new URL(localLoginUrl);
        final boolean isValidatedLocalLoginUrl = request.getRequestURI().endsWith(url.getPath()) &&
            CommonUtils.isNotBlank(request.getParameter("validated"));
        
        if (!isValidatedLocalLoginUrl && CommonUtils.isBlank(ticket) && assertion == null && !wasGatewayed) {
            log.debug("no ticket and no assertion found");
            if (this.gateway) {
                log.debug("setting gateway attribute in session");
                request.getSession(true).setAttribute(CONST_CAS_GATEWAY, "yes");
            }


            final String serviceUrl = constructServiceUrl(request, response);


            if (log.isDebugEnabled()) {
                log.debug("Constructed service url: " + serviceUrl);
            }


            String urlToRedirectTo = CommonUtils.constructRedirectUrl(
                    this.casServerLoginUrl, getServiceParameterName(),
                    serviceUrl, this.renew, this.gateway);


            // 加入localLoginUrl
            urlToRedirectTo += (urlToRedirectTo.contains("?") ? "&" : "?") + "loginUrl=" + URLEncoder.encode(localLoginUrl, "utf-8");


            if (log.isDebugEnabled()) {
                log.debug("redirecting to \"" + urlToRedirectTo + "\"");
            }
            
            response.sendRedirect(urlToRedirectTo);
            return;
        }


        if (session != null) {
            log.debug("removing gateway attribute from session");
            session.setAttribute(CONST_CAS_GATEWAY, null);
        }


        filterChain.doFilter(request, response);
    }


    public final void setRenew(final boolean renew) {
        this.renew = renew;
    }


    public final void setGateway(final boolean gateway) {
        this.gateway = gateway;
    }


    public final void setCasServerLoginUrl(final String casServerLoginUrl) {
        this.casServerLoginUrl = casServerLoginUrl;
    }


    public final void setLocalLoginUrl(String localLoginUrl) {
        this.localLoginUrl = localLoginUrl;
    }
    
}
最后编写登录页面，启动tomcat报错信息如下：

严重: Exception starting filter CAS Filter
java.lang.IllegalArgumentException: serverName or service must be set.
at org.jasig.cas.client.util.CommonUtils.assertTrue(CommonUtils.java:116)
at org.jasig.cas.client.util.AbstractCasFilter.init(AbstractCasFilter.java:103)
at com.cas.client.validation.RemoteAuthenticationFilter.init(RemoteAuthenticationFilter.java:57)
at org.jasig.cas.client.util.AbstractCasFilter.init(AbstractCasFilter.java:84)
at org.apache.catalina.core.ApplicationFilterConfig.initFilter(ApplicationFilterConfig.java:279)
at org.apache.catalina.core.ApplicationFilterConfig.getFilter(ApplicationFilterConfig.java:260)
at org.apache.catalina.core.ApplicationFilterConfig.<init>(ApplicationFilterConfig.java:105)
at org.apache.catalina.core.StandardContext.filterStart(StandardContext.java:4809)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5485)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:901)
at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:877)
at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:632)
at org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.java:1247)
at org.apache.catalina.startup.HostConfig$DeployDirectory.run(HostConfig.java:1898)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:439)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
at java.util.concurrent.FutureTask.run(FutureTask.java:138)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:895)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:918)
at java.lang.Thread.run(Thread.java:662)
2014-7-17 11:15:23 org.apache.catalina.core.StandardContext startInternal
严重: Error filterStart
2014-7-17 11:15:23 org.apache.catalina.core.StandardContext startInternal
严重: Context [/casclient] startup failed due to previous errors