fix(material): 修复关键字查询导致无结果的问题

src/main/java/mjkf/xinke/main/controller/MaterialController.java

@@ -1,8 +1,8 @@
 package mjkf.xinke.main.controller;
 
+import cn.hutool.core.util.ObjectUtil;
 import cn.hutool.core.util.StrUtil;
 import com.baomidou.mybatisplus.core.conditions.query.LambdaQueryWrapper;
-import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
 import com.jgy.xxs.core.common.util.CommonUtil;
 import com.jgy.xxs.core.http.exp.NcHttpException;
 import com.jgy.xxs.core.http.resp.HttpResponse;
@@ -70,7 +70,7 @@ public class MaterialController {
         if (parentId != null) {
             query.eq(Material::getParentId, parentId);
         }
-        if (keyWord != null) {
+        if (keyWord != null && ObjectUtil.isNotEmpty(keyWord)) {
             query.and(q -> q
                     .like(Material::getCategory1, keyWord).or()
                     .like(Material::getCategory2, keyWord).or()