filter中获取spring bean

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.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;import org.apache.commons.lang.StringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.web.context.WebApplicationContext;import com.alibaba.fastjson.JSON;
import com.viewalloc.base.common.model.contants.ResultCodeType;
import com.viewalloc.base.common.model.dto.InvokeResult;
import com.viewalloc.base.common.redis.VARedisTemplate;
import com.viewalloc.scan.admin.common.utils.CookieUtils;public class LoginFilter  implements Filter {    private WebApplicationContext wac;    private Logger log = LoggerFactory.getLogger(this.getClass());    @Override
    public void destroy() {    }    private static final String[] NO_FILTER_URL = new String[]{"/api/user/session","/api/user/logout","login.html","/api/version"};    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
            throws IOException, ServletException {
        VARedisTemplate redis = wac.getBean(VARedisTemplate.class);
    }    @Override
    public void init(FilterConfig arg0) throws ServletException {
        wac = (WebApplicationContext) arg0.getServletContext().getAttribute(WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE);
    }}