@TableField(value ="create_time",fill = FieldFill.INSERT)    //插入時(shí)填充字段
    private LocalDateTime createTime;
    @TableField(value ="update_time",fill = FieldFill.INSERT_UPDATE)//插入和更新時(shí)填充字段
    private LocalDateTime updateTime;
    @TableField(value = "create_user",fill = FieldFill.INSERT)//插入時(shí)填充字段
    private Long createUser;
    @TableField(value = "update_user",fill = FieldFill.INSERT_UPDATE)//插入和更新時(shí)填充字段
    private Long updateUser;

package com.reggie_take_out.common;
import com.baomidou.mybatisplus.core.handlers.MetaObjectHandler;
import lombok.extern.slf4j.Slf4j;
import org.apache.ibatis.reflection.MetaObject;
import org.springframework.stereotype.Component;
import java.time.LocalDateTime;
/**
 * 元數(shù)據(jù)對(duì)象處理器
 */
@Component
@Slf4j
public class MyMetaObjectHandler implements MetaObjectHandler {
    /**
     * 執(zhí)行insert語句的時(shí)候執(zhí)行
     *
     * @param metaObject
     */
    @Override
    public void insertFill(MetaObject metaObject) {
        log.info("公共字段自動(dòng)填充——insertFill");
//      自動(dòng)填充
        metaObject.setValue("createTime", LocalDateTime.now());
        metaObject.setValue("updateTime", LocalDateTime.now());
//      獲取session對(duì)象
        metaObject.setValue("createUser", BaseContext.getCurrentId());
        metaObject.setValue("updateUser", BaseContext.getCurrentId());
    }
    /**
     * 執(zhí)行update語句的時(shí)候執(zhí)行
     *
     * @param metaObject
     */
    @Override
    public void updateFill(MetaObject metaObject) {
        log.info("公共字段自動(dòng)填充——updateFill");
        metaObject.setValue("updateTime", LocalDateTime.now());
        metaObject.setValue("updateUser", BaseContext.getCurrentId());
    }
}

 request.getSession().getAttribute("employee");

/**
 * 基于ThreadLocal封裝工具類，用戶保存和獲取當(dāng)前登錄用戶id
 */
public class BaseContext {
    private static ThreadLocal<Long> threadLocal = new ThreadLocal<>();
    public static void setCurrentId(Long id){
        threadLocal.set(id);
    }
    public static Long getCurrentId(){
        return threadLocal.get();
    }
}

/**
 * 檢查用戶是否已經(jīng)完成登錄
 * 過濾器與攔截器的區(qū)別：Filter對(duì)所有訪問進(jìn)行增強(qiáng)（在Tomcat服務(wù)器進(jìn)行配置），Interceptor僅針對(duì)SpringMVC的訪問進(jìn)行增強(qiáng)
 */
@Slf4j
@WebFilter(filterName = "loginCheckFilter", urlPatterns = "/*")  //urlPatterns指定攔截哪些路徑
public class LoginCheckFilter implements Filter {
    //  此對(duì)象的作用：路徑匹配器，  匹配路徑時(shí)支持通配符
    public static final AntPathMatcher PATH_MATCHER = new AntPathMatcher();
    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
//      servletRequest向下強(qiáng)制類型轉(zhuǎn)換
        HttpServletRequest request = (HttpServletRequest) servletRequest;
        HttpServletResponse response = (HttpServletResponse) servletResponse;
        //1. 獲取本次請(qǐng)求的URI( URI:請(qǐng)求的資源路徑)
        String requestURI = request.getRequestURI();
        log.info("攔截到請(qǐng)求:{}", request.getRequestURI());
        // 定義不用處理的請(qǐng)求路徑
        String[] urls = new String[]{
                "/employee/login",
                "/employee/logout",
                "/backend/**",
                "/front/**"
        };
        //2. 判斷本次請(qǐng)求是否需要處理（因?yàn)橛行┱?qǐng)求并不需要用戶登錄）
        boolean check = check(requestURI, urls);
        //3.如果不需要處理，則直接放行
        if (check) {
            log.info("本次請(qǐng)求{}不需要處理", request.getRequestURI());
            filterChain.doFilter(request, response);
            return;
        }
        //4.判斷登錄狀態(tài)，如果已登錄，則直接放行.從session中獲取用戶，如果獲取到說明已經(jīng)登錄
        if (request.getSession().getAttribute("employee") != null) {
            log.info("用戶已登錄，用戶id為{}", request.getSession().getAttribute("employee"));
            Long empId = (Long) request.getSession().getAttribute("employee");
            BaseContext.setCurrentId(empId);
            filterChain.doFilter(request, response);
            return;
        }
        //5.如果未登錄則返回未登錄結(jié)果
        log.info("資源路徑路徑：{}，用戶未登錄{}", request.getRequestURI(), request.getSession().getAttribute("employee"));
//           通過輸出流的方式向客戶端響應(yīng)數(shù)據(jù)   (為什么要返回這個(gè)NOTLOGIN？  因?yàn)榍岸诵枰@個(gè)來進(jìn)行判定是否登錄)
        response.getWriter().write(JSON.toJSONString(R.error("NOTLOGIN")));
//        filterChain.doFilter(request, response);  加上這個(gè)就無法實(shí)現(xiàn)
    }
    /**
     * 檢查本次請(qǐng)求是否需要放行
     *
     * @param requestURI 請(qǐng)求的資源路徑
     * @param urls       放過的路徑
     * @return true 放行
     */
    public boolean check(String requestURI, String[] urls) {
        for (String url : urls) {
            boolean match = PATH_MATCHER.match(url, requestURI);
            if (match) {
//           放行
                return true;
            }
        }
        return false;
    }
}

package com.reggie_take_out.common;
import com.baomidou.mybatisplus.core.handlers.MetaObjectHandler;
import lombok.extern.slf4j.Slf4j;
import org.apache.ibatis.reflection.MetaObject;
import org.springframework.stereotype.Component;
import java.time.LocalDateTime;
/**
 * 元數(shù)據(jù)對(duì)象處理器
 */
@Component
@Slf4j
public class MyMetaObjectHandler implements MetaObjectHandler {
    /**
     * 執(zhí)行insert語句的時(shí)候執(zhí)行
     *
     * @param metaObject
     */
    @Override
    public void insertFill(MetaObject metaObject) {
        log.info("公共字段自動(dòng)填充——insertFill");
//      自動(dòng)填充
        metaObject.setValue("createTime", LocalDateTime.now());
        metaObject.setValue("updateTime", LocalDateTime.now());
//      獲取session對(duì)象
        metaObject.setValue("createUser", BaseContext.getCurrentId());
        metaObject.setValue("updateUser", BaseContext.getCurrentId());
    }
    /**
     * 執(zhí)行update語句的時(shí)候執(zhí)行
     *
     * @param metaObject
     */
    @Override
    public void updateFill(MetaObject metaObject) {
        log.info("公共字段自動(dòng)填充——updateFill");
        metaObject.setValue("updateTime", LocalDateTime.now());
        metaObject.setValue("updateUser", BaseContext.getCurrentId());
    }
}