[Java知识库]拦截器引入redisUtil为null

原因：拦截器在bean初始化前执行的，这时候redisUtil是null，需要通过下面这个方式去获取

主要解决的代码：
WebApplicationContext wac = WebApplicationContextUtils.getRequiredWebApplicationContext(request.getServletContext());
redisOpsUtil = wac.getBean(RedisOpsUtil.class);

package com.hzh.studyonline.config;
import com.hzh.studyonline.util.JwtUtil;
import com.hzh.studyonline.util.RedisOpsUtil;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.context.support.WebApplicationContextUtils;
import org.springframework.web.method.HandlerMethod;
import org.springframework.web.servlet.HandlerInterceptor;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.lang.reflect.Method;

//新建拦截器，在token验证前执行
@Slf4j
public class AuthenticationInterceptor implements HandlerInterceptor {
    @Autowired
    RedisOpsUtil redisOpsUtil;

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {

        String token = request.getHeader("token");
        String phone = request.getHeader("phone");
        // 如果不是映射到方法直接通过
        if(!(handler instanceof HandlerMethod)){
            return true;
        }
        //如果接口或者类上有@JwtIgnore注解，意思该接口不需要token就能访问，需要放行
        HandlerMethod handlerMethod = (HandlerMethod) handler;
        Method method = handlerMethod.getMethod();
        //先从类上获取该注解，判断类上是否加了@JwtIgnore ，代表不需要token，直接放行
        JwtIgnore annotation = handlerMethod.getBeanType().getAnnotation(JwtIgnore.class);
        if(annotation == null){
            //再从方法上获取该注解
            if(method.isAnnotationPresent(JwtIgnore.class)){
                annotation = method.getAnnotation(JwtIgnore.class);
                log.info("请求方法 {} 上有注解 {} ",method.getName(),annotation);
            }
        }
        if (annotation!=null){
            return true;
        }

        //开始检验没有权限的接口
        //1、jwt解析正确
        JwtUtil jwtUtil = new JwtUtil();
        boolean parse = jwtUtil.parse(token);
        //2、从redis中获取的token一致
        if (redisOpsUtil==null){
            //拦截器在bean初始化前执行的，这时候redisUtil是null，需要通过下面这个方式去获取
            WebApplicationContext wac = WebApplicationContextUtils.getRequiredWebApplicationContext(request.getServletContext());
            redisOpsUtil = wac.getBean(RedisOpsUtil.class);
        }
        String redisToken =(String) redisOpsUtil.hget("token", phone);
        if (redisToken==null){
            log.info("redisToken过期 电话是：{} 的用户 ",phone);
            return false;
        }
        if (parse==true && redisToken.equals(token)){
            return true;
        }
        return false;
    }


}