一、需求背景：
在使用token进行登录的过程中，如果token过期了，需要重新输入用户名和密码登录，这种体验肯定是不好的，因为如果一直在使用系统，系统应该一直能够保持登录状态，而不是用着用着就突然退出系统重新登录。
二、解决方法：
生成token的接口需要提供，token和刷新的refresh_token ,过期时间。当时间快过期时，重新调用后端接口去获取新的token。
token：包含了凭证相关信息（过期时间相对refresh_token短）
refresh_token：包含凭证相关信息（过期时间相对token长）
过期时间：给客户端计算何时需要使用refresh_token来换取新的token
生成token参照，里面在加上 refresh_token和过期时间就可以。
JAVA开发（JWTUtil工具类实现token源码赏析）_茅河野人的博客-CSDN博客
三、后端验证token的示例：
既可以通过过滤器，也可以使用拦截器来拦截。
import javax.annotation.Resource;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cloud.gateway.filter.GatewayFilterChain;
import org.springframework.cloud.gateway.filter.GlobalFilter;
import org.springframework.core.Ordered;
import org.springframework.core.io.buffer.DataBufferFactory;
import org.springframework.data.redis.core.ValueOperations;
import org.springframework.http.HttpStatus;
import org.springframework.http.MediaType;
import org.springframework.http.server.reactive.ServerHttpRequest;
import org.springframework.http.server.reactive.ServerHttpResponse;
import org.springframework.stereotype.Component;
import org.springframework.web.server.ServerWebExchange;
import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONObject;
import com.ruoyi.common.core.constant.CacheConstants;
import com.ruoyi.common.core.constant.Constants;
import com.ruoyi.common.core.domain.R;
import com.ruoyi.common.core.utils.StringUtils;
import com.ruoyi.common.redis.service.RedisService;
import com.ruoyi.gateway.config.properties.IgnoreWhiteProperties;
import reactor.core.publisher.Mono;/*** 网关鉴权*/
@Component
public class AuthFilter implements GlobalFilter, Ordered
{private static final Logger log = LoggerFactory.getLogger(AuthFilter.class);private final static long EXPIRE_TIME = Constants.TOKEN_EXPIRE * 60;// 排除过滤的 uri 地址，nacos自行添加@Autowiredprivate IgnoreWhiteProperties ignoreWhite;@Resource(name = "stringRedisTemplate")private ValueOperations<String, String> sops;@Autowiredprivate RedisService redisService;@Overridepublic Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain){String url = exchange.getRequest().getURI().getPath();// 跳过不需要验证的路径if (StringUtils.matches(url, ignoreWhite.getWhites())){return chain.filter(exchange);}String token = getToken(exchange.getRequest());if (StringUtils.isBlank(token)){return setUnauthorizedResponse(exchange, "令牌不能为空");}String userStr = sops.get(getTokenKey(token));if (StringUtils.isNull(userStr)){return setUnauthorizedResponse(exchange, "登录状态已过期");}JSONObject obj = JSONObject.parseObject(userStr);String userid = obj.getString("userid");String username = obj.getString("username");if (StringUtils.isBlank(userid) || StringUtils.isBlank(username)){return setUnauthorizedResponse(exchange, "令牌验证失败");}// 设置过期时间redisService.expire(getTokenKey(token), EXPIRE_TIME);// 设置用户信息到请求ServerHttpRequest mutableReq = exchange.getRequest().mutate().header(CacheConstants.DETAILS_USER_ID, userid).header(CacheConstants.DETAILS_USERNAME, username).build();ServerWebExchange mutableExchange = exchange.mutate().request(mutableReq).build();return chain.filter(mutableExchange);}private Mono<Void> setUnauthorizedResponse(ServerWebExchange exchange, String msg){ServerHttpResponse response = exchange.getResponse();response.getHeaders().setContentType(MediaType.APPLICATION_JSON);response.setStatusCode(HttpStatus.OK);log.error("[鉴权异常处理]请求路径:{}", exchange.getRequest().getPath());return response.writeWith(Mono.fromSupplier(() -> {DataBufferFactory bufferFactory = response.bufferFactory();return bufferFactory.wrap(JSON.toJSONBytes(R.fail(msg)));}));}private String getTokenKey(String token){return CacheConstants.LOGIN_TOKEN_KEY + token;}/*** 获取请求token*/private String getToken(ServerHttpRequest request){String token = request.getHeaders().getFirst(CacheConstants.HEADER);if (StringUtils.isNotEmpty(token) && token.startsWith(CacheConstants.TOKEN_PREFIX)){token = token.replace(CacheConstants.TOKEN_PREFIX, "");}return token;}@Overridepublic int getOrder(){return -200;}
}
