Interceptor拦截器入门知识及其工作原理

Interceptor拦截器入门知识及其工作原理

一、入门知识

1.1总述

1.2案例代码

import com.hechixueyuan.forestfiredetectionsystem.pojo.Result;
import com.hechixueyuan.forestfiredetectionsystem.utils.JwtUtils;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Component;
import org.springframework.util.StringUtils;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;
@Slf4j
//定义拦截器
@Component
public class LoginCheckInterceptor implements HandlerInterceptor {@Override
//    该方法在目标资源方法运行前运行，返回Ture则放行，返回false则不放行public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {String url = request.getRequestURI().toString();log.info("请求url：{}",url);// 1. 处理跨域：允许OPTIONS预检请求直接放行if ("OPTIONS".equalsIgnoreCase(request.getMethod())) {log.info("OPTIONS预检请求，放行");
//            在拦截器中的放行操作是return turereturn true;}if(url.contains("login")){log.info("登录操作，放行...");return true;}
//        获取请求头当中的令牌String jwt = request.getHeader("token");
// 5. 判断令牌是否存在if (!StringUtils.hasLength(jwt)) {log.info("令牌不存在，返回错误信息");
//            不能放行return false;}// 6. 解析令牌，失败则返回未登录try {JwtUtils.parseJWT(jwt); // 确保JwtUtils的parseJWT方法正确实现} catch (Exception e) {log.info("令牌解析失败，错误信息：{}", e.getMessage());
//            不能放行return false;}// 7. 令牌有效，放行log.info("令牌有效，放行...");return true;}@Overridepublic void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {System.out.println("postHandle");}@Overridepublic void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {System.out.println("afterCompletion");}
}

二、工作原理