無法導入servlet類

請人我是新中的servlet我創建了日食的項目，並在其後添加新的servlet我有很多在它的錯誤的和無法修復無法導入servlet類

和所有導入行上有一個紅色下劃線，並且無法修復它這是配置中的問題嗎？或者什麼

/** 
* Servlet implementation class ServletTest 
*/ 
@WebServlet(
     description = "first servlet test", 
     urlPatterns = { 
       "/ServletTest", 
       "/ServletTestPath" 
     }) 
public class ServletTest extends HttpServlet { 
    private static final long serialVersionUID = 1L; 

    /** 
    * Default constructor. 
    */ 
    public ServletTest() { 
     // TODO Auto-generated constructor stub 
    } 

    /** 
    * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response) 
    */ 
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { 
     // TODO Auto-generated method stub 
     response.getWriter().append("Served at: ").append(request.getContextPath()); 
    } 

}

來源

2016-04-16 Hamada Ibrahim

您是否嘗試過安裝服務器？（如Tomcat） –