WebClient();org.w3c.css.sac.ErrorHandler

有的页面要动态加载完，爬虫才能拿到完整信息，于是在网上找到了 HTMLunit 封装的办法但是：
执行到 WebClient webClient = new WebClient();
就报：
ClassNotFoundException: org.w3c.css.sac.ErrorHandler
package htmlunit;
 
import java.io.IOException;
import java.net.MalformedURLException;
 
import org.htmlparser.visitors.HtmlPage;
 
import com.gargoylesoftware.htmlunit.FailingHttpStatusCodeException;
import com.gargoylesoftware.htmlunit.WebClient;
 
public class WebClientTest {
    public static void main(String args[]){
        final WebClient webClient = new WebClient();
        HtmlPage page;
        try {
            page = webClient.getPage("http://www.youerw.com");
            System.out.println(page.toString());
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        
        webClient.closeAllWindows();
    }
 
    
}

 org.w3c.css.sac.ErrorHandler这个类你有吗？包都加全了吗？