在Java项目中配置Redis拦截器

在Java项目中配置Redis拦截器

在javaWeb项目中，免不了使用Redis作为缓存，但是在开始学习时，会在每个请求前进行拦截进行是否有缓存判断，这样十分没有效率。通常方法应该是利用RedisKey进行缓存命中判断，来进行统一的拦截判断。

一、在Redis中存入RedisKey以及相应的Data RedisKey：为相应的请求参数进行MD5加密后生成的字符串。 Data：为相应请求的返回结果。

二、编写拦截器以及RedisKey生成方法

package com.dbh123.interceptor;

import com.fasterxml.jackson.databind.ObjectMapper;
import org.apache.commons.codec.digest.DigestUtils;
import org.apache.commons.io.IOUtils;
import org.apache.commons.lang3.StringUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.stereotype.Component;
import org.springframework.web.servlet.HandlerInterceptor;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.util.Map;

@Component
public class RedisCacheInterceptor implements HandlerInterceptor {
          
   

    @Autowired
    private RedisTemplate<String, String> redisTemplate;
    private static ObjectMapper mapper = new ObjectMapper();

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
          
   
        //判断请求方法只有get方法才拦截 因为只有在请求结果时才会用到缓存
        if (!StringUtils.equals(request.getMethod() , "get")){
          
   
            //当不为get方法时 因为这里用到graphQL，所以还需在post中拦截graphql请求
            if (!StringUtils.equals(request.getRequestURI() , "/graphql")){
          
   
                return true;
            }
        }
        //创建Rediskey
        String redisKey = createRedisKey(request);
        //从Redis获取数据
        String data = this.redisTemplate.opsForValue().get(redisKey);
        if (StringUtils.isEmpty(data)) {
          
   
        //若为空则缓存未命中 通过
            return true;
        }
        //命中填加缓存数据 返回
        response.setCharacterEncoding("UTF-8");
        response.setContentType("application/json; charset=utf-8");
        response.getWriter().write(data);
        return false;
    }


    /**
     *  ReidsKey 创建方法
     * @param request
     * @return
     * @throws Exception
     */
    public static String createRedisKey(HttpServletRequest request) throws
            Exception {
          
   
        //1.获取url
        String paramStr = request.getRequestURI();
        //2.获取参数
        Map<String, String[]> parameterMap = request.getParameterMap();
        if (parameterMap.isEmpty()) {
          
   
            //参数为空，及为post方法并通过输入流获取数据 加入参数
            paramStr += IOUtils.toString(request.getInputStream(), "UTF-8");}
            else {
          
   
            //将参数加入url中
            paramStr += mapper.writeValueAsString(request.getParameterMap());
        }
        //调用MD5方法将url生成Rediskey
        String redisKey = "WEB_DATA_" + DigestUtils.md5Hex(paramStr);
        return redisKey;
    }

}

三、注册拦截器

package com.dbh123.configuration;

import cn.itcast.haoke.dubbo.api.interceptor.RedisCacheInterceptor;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

@Configuration
public class WebConfig implements WebMvcConfigurer {
          
   
    @Autowired
    private RedisCacheInterceptor redisCacheInterceptor;
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
          
   
        registry.addInterceptor(this.redisCacheInterceptor).addPathPatterns("/**");
    }
}