快速入门Interceptor拦截器

1.概念

2.执行流程

3.WebConfig配置类

package com.hz.config;

import com.hz.interceptor.LoginCheckInterceptor;
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//配置类
public class WebConfig implements WebMvcConfigurer {

    @Autowired
    private LoginCheckInterceptor loginCheckInterceptor;
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(loginCheckInterceptor).addPathPatterns("/**").excludePathPatterns("/login");
    }
}

4.LoginCheckInterceptor示例

package com.hz.interceptor;

import com.alibaba.fastjson.JSONObject;
import com.hz.pojo.Result;
import com.hz.utils.JwtUtils;
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;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@Slf4j
@Component
public class LoginCheckInterceptor implements HandlerInterceptor {
    @Override//目标资源方法运行前运行，返回true，放行，返回false，不放行
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {

        //获取请求url
        String url = request.getRequestURL().toString();
        log.info("请求的url: {}",url);

        //判断请求的url中是否包含login
        if(url.contains("login")){
            log.info("登录操作，放行~~~");
            //放行
            return true;
        }

        //获取请求头中的令牌（token）
        String jwt = request.getHeader("token");

        //判断令牌是否存在，如不存在，则返回错误提示信息
        if(!StringUtils.hasLength(jwt)){
            log.info("请求头token为空，返回未登录的信息");
            Result error = Result.error("NOT_LOGIN");
            //手动转换
            //对象 ---> JSON
            String notLogin = JSONObject.toJSONString(error);
            response.getWriter().write(notLogin);
            return false;
        }

        //解析token，如果解析失败，返回错误结果
        try {
            JwtUtils.parseJWT(jwt);
        } catch (Exception e) {
            e.printStackTrace();
            log.info("解析令牌失败，返回未登录的错误信息");
            Result error = Result.error("NOT_LOGIN");
            //手动转换
            //对象 ---> JSON
            String notLogin = JSONObject.toJSONString(error);
            response.getWriter().write(notLogin);
            return false;
        }

        //放行
        log.info("令牌合法，放行~~~");
        return true;

    }

    @Override//目标资源方法运行后运行
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {

    }

    @Override//视图渲染完毕后运行，最后运行
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {

    }
}