getServletContext()找不到這個路徑

我的一開始的源碼是：

public class BankInterceptor extends HandlerInterceptorAdapter {

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
            throws Exception {
        
         String username =  (String)request.getSession().getAttribute("adminusername");   
            if(username == null){
               
               response.sendRedirect(request.getServletContext().getContextPath()+"/admin/login");
                return false;  
            }else  
                return true;     
    }

 

下面是報錯：

 

 

 

方法一：

getServletContext().getContextPath() 沒有這個方法當然報錯了。
你可以用request.getContextPath();

 

public class BankInterceptor extends HandlerInterceptorAdapter {

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
            throws Exception {
        
         String username =  (String)request.getSession().getAttribute("adminusername");   
            if(username == null){
               
               response.sendRedirect(request.getServletContext().getContextPath()+"/admin/login");
                return false;  
            }else  
                return true;     
    }

方法二：

在一開始的基礎上加上.getSession()

public class BankInterceptor extends HandlerInterceptorAdapter {

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
            throws Exception {
        
         String username =  (String)request.getSession().getAttribute("adminusername");   
            if(username == null){
               
               response.sendRedirect(request.getSession().getServletContext().getContextPath()+"/admin/login");
                return false;  
            }else  
                return true;     
    }