Apereo CAS 5.3.x:登录到java CAS客户端后，如何从cas服务器获取登录用户

import org.jasig.cas.client.authentication.AttributePrincipal;
import org.jasig.cas.client.util.AbstractCasFilter;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

public class MyCasFilter extends AbstractCasFilter {

    @Override
    protected void initInternal(FilterConfig filterConfig) throws ServletException {
        super.initInternal(filterConfig);
    }

    @Override
    public void doFilter(HttpServletRequest request, HttpServletResponse response, javax.servlet.FilterChain filterChain) throws IOException, ServletException {
        // 检查用户是否已经通过 CAS 认证
        AttributePrincipal principal = (AttributePrincipal) request.getUserPrincipal();
        if (principal != null) {
            // 获取登录用户的名称
            String username = principal.getName();
            // 获取登录用户的属性
            Map<String, Object> attributes = principal.getAttributes();
            // 处理用户信息...
        }

        filterChain.doFilter(request, response);
    }
}