Eclipse中的字段未使用警告

我正在JSF應用程序中實現登錄過濾器。我有一個私人領域稱爲配置。儘管在init和destroy方法中引用了該字段，但Eclipse會顯示警告「字段AuthenticationFilter.config的值未使用」。我在這裏做錯了什麼，或者是Eclipse有點困惑？Eclipse中的字段未使用警告

這裏的AuthenticationFilter類：

package com.mymato.coop; 

import java.io.IOException; 

import javax.servlet.Filter; 
import javax.servlet.FilterChain; 
import javax.servlet.FilterConfig; 
import javax.servlet.ServletException; 
import javax.servlet.ServletRequest; 
import javax.servlet.ServletResponse; 
import javax.servlet.annotation.WebFilter; 
import javax.servlet.http.HttpServletRequest; 
import javax.servlet.http.HttpServletResponse; 

@WebFilter("/restricted/*") 
public class AuthenticationFilter implements Filter { 

     private FilterConfig config; 

     public void doFilter(ServletRequest req, ServletResponse resp, 
      FilterChain chain) throws IOException, ServletException { 
     if (((HttpServletRequest) req).getSession().getAttribute(
      LoginBean.AUTH_KEY) == null) { 
      ((HttpServletResponse) resp).sendRedirect("../login.xhtml"); 
     } else { 
      chain.doFilter(req, resp); 
     } 
     } 

     public void init(FilterConfig config) throws ServletException { 
     this.config = config; 
     } 

     public void destroy() { 
     config = null; 
     } 
    }

來源

2016-07-23 tommccann