refactor: 使用 Hutool工具类优化空值判断- 在多个控制器和服务实现类中，将原始的空值判断替换为 Hutool 工具类中的方法

- 使用 ObjectUtil.isNull() 替换原始的 == null 判断
- 使用 ObjectUtil.isNotNull() 替换原始的 != null 判断
- 在某些情况下，使用 StrUtil.isBlank() 替换原始的 == null 判断，以更准确地检查字符串是否为空

biji-houdaun/src/main/java/com/test/bijihoudaun/controller/GroupingController.java

@@ -1,6 +1,7 @@
 package com.test.bijihoudaun.controller;
 
 import cn.hutool.core.util.StrUtil;
+import cn.hutool.core.util.ObjectUtil;
 import com.test.bijihoudaun.common.response.R;
 import com.test.bijihoudaun.entity.Grouping;
 import com.test.bijihoudaun.service.GroupingService;
@@ -24,7 +25,7 @@ public class GroupingController {
     @Operation(summary = "创建分组")
     @PostMapping
     public R<Grouping> createGrouping(@RequestBody Grouping grouping) {
-        if (grouping.getParentId() == null) {
+        if (ObjectUtil.isNull(grouping.getParentId())) {
             grouping.setParentId(0L);
         }
         Grouping created = groupingService.createGrouping(grouping);

biji-houdaun/src/main/java/com/test/bijihoudaun/controller/ImageController.java

@@ -1,6 +1,7 @@
 package com.test.bijihoudaun.controller;
 
 
+import cn.hutool.core.util.StrUtil;
 import com.test.bijihoudaun.common.response.R;
 import com.test.bijihoudaun.entity.Image;
 import com.test.bijihoudaun.service.ImageService;
@@ -63,7 +64,7 @@ public class ImageController {
     @GetMapping("/preview/{url}")
     @Operation(summary = "在线预览", description = "浏览器直接打开文件流")
     public void preview(@PathVariable String url, HttpServletResponse resp) throws IOException {
-        if (url == null) {
+        if (StrUtil.isBlank(url)) {
             resp.setStatus(404);
             R.fail("文件不存在");
         }
@@ -113,7 +114,7 @@ public class ImageController {
      * @return 对应的MIME类型
      */
     private String getContentTypeFromFileExtension(String fileName) {
-        if (fileName == null || fileName.lastIndexOf('.') == -1) {
+        if (StrUtil.isBlank(fileName) || !StrUtil.contains(fileName, '.')) {
             return "application/octet-stream";
         }
 

biji-houdaun/src/main/java/com/test/bijihoudaun/controller/MarkdownController.java

@@ -1,5 +1,6 @@
 package com.test.bijihoudaun.controller;
 
+import cn.hutool.core.util.ObjectUtil;
 import com.test.bijihoudaun.common.response.R;
 import com.test.bijihoudaun.entity.MarkdownFile;
 import com.test.bijihoudaun.entity.MarkdownFileVO;
@@ -36,7 +37,7 @@ public class MarkdownController {
     @GetMapping("/{id}")
     public R<String> getMarkdownContent(@PathVariable Long id) {
         MarkdownFile file = markdownFileService.getMarkdownById(id);
-        if (file != null) {
+        if (ObjectUtil.isNotNull(file)) {
             return R.success(file.getContent());
         }
         return R.fail();
@@ -89,7 +90,7 @@ public class MarkdownController {
             @PathVariable Long id,
             @RequestBody String title) {
         MarkdownFile updatedFile = markdownFileService.updateMarkdownTitle(id, title);
-        if (updatedFile != null) {
+        if (ObjectUtil.isNotNull(updatedFile)) {
             return R.success(updatedFile);
         }
         return R.fail("文件未找到或更新失败");

biji-houdaun/src/main/java/com/test/bijihoudaun/controller/UserController.java

@@ -1,6 +1,7 @@
 package com.test.bijihoudaun.controller;
 
 import com.test.bijihoudaun.bo.UpdatePasswordBo;
+import cn.hutool.core.util.ObjectUtil;
 import com.test.bijihoudaun.common.response.R;
 import com.test.bijihoudaun.entity.User;
 import com.test.bijihoudaun.service.RegistrationCodeService;
@@ -69,7 +70,7 @@ public class UserController {
         String username = userDetails.getUsername();
         User user = userService.getOne(new com.baomidou.mybatisplus.core.conditions.query.QueryWrapper<User>().eq("username", username));
 
-        if (user == null) {
+        if (ObjectUtil.isNull(user)) {
             return R.fail("无法获取用户信息，删除失败");
         }
 

biji-houdaun/src/main/java/com/test/bijihoudaun/service/impl/GroupingServiceImpl.java

@@ -1,6 +1,7 @@
 package com.test.bijihoudaun.service.impl;
 
 import com.baomidou.mybatisplus.core.conditions.query.LambdaQueryWrapper;
+import cn.hutool.core.util.ObjectUtil;
 import com.baomidou.mybatisplus.core.conditions.update.LambdaUpdateWrapper;
 import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
 import com.test.bijihoudaun.entity.Grouping;
@@ -39,7 +40,7 @@ public class GroupingServiceImpl
 
     @Override
     public List<Grouping> getAllGroupings(Long parentId) {
-        if (parentId == null){
+        if (ObjectUtil.isNull(parentId)){
             return groupingMapper.selectList(null);
         }
         return groupingMapper.selectList(new LambdaQueryWrapper<Grouping>()

biji-houdaun/src/main/java/com/test/bijihoudaun/service/impl/ImageServiceImpl.java

@@ -2,6 +2,7 @@ package com.test.bijihoudaun.service.impl;
 
 import cn.hutool.core.collection.CollUtil;
 import cn.hutool.core.stream.CollectorUtil;
+import cn.hutool.core.util.ObjectUtil;
 import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
 
 import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
@@ -68,7 +69,7 @@ public class ImageServiceImpl
     @Override
     public boolean deleteImage(Long id) {
         Image image = imageMapper.selectById(id);
-        if (image == null) {
+        if (ObjectUtil.isNull(image)) {
             return false;
         }
         try {
@@ -87,7 +88,7 @@ public class ImageServiceImpl
     @Override
     public boolean deleteImageByUrl(String url) {
         Image image = imageMapper.selectOne(new QueryWrapper<Image>().eq("url", url));
-        if (image == null) {
+        if (ObjectUtil.isNull(image)) {
             return false;
         }
         try {
@@ -109,7 +110,7 @@ public class ImageServiceImpl
         }
         for (String url : urls) {
             Image image = imageMapper.selectOne(new QueryWrapper<Image>().eq("url", url));
-            if (image != null) {
+            if (ObjectUtil.isNotNull(image)) {
                 this.deleteImageByUrl(url);
             }
         }

biji-houdaun/src/main/java/com/test/bijihoudaun/service/impl/MarkdownFileServiceImpl.java

@@ -1,6 +1,7 @@
 package com.test.bijihoudaun.service.impl;
 
 import cn.hutool.core.collection.CollUtil;
+import cn.hutool.core.util.ObjectUtil;
 import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
 import com.baomidou.mybatisplus.core.conditions.update.LambdaUpdateWrapper;
 import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
@@ -40,7 +41,7 @@ public class MarkdownFileServiceImpl
         long id;
         markdownFile.setUpdatedAt(new Date());
         // 如果ID为空或0，则视为新文件
-        if (markdownFile.getId() == null || markdownFile.getId() == 0L) {
+        if (ObjectUtil.isNull(markdownFile.getId()) || markdownFile.getId() == 0L) {
             long l = snowflakeIdGenerator.nextId();
             markdownFile.setId(l);
             markdownFile.setCreatedAt(new Date());
@@ -97,7 +98,7 @@ public class MarkdownFileServiceImpl
     @Override
     public MarkdownFile updateMarkdownTitle(Long id, String title) {
         MarkdownFile file = this.getById(id);
-        if (file != null) {
+        if (ObjectUtil.isNotNull(file)) {
             file.setTitle(title);
             file.setUpdatedAt(new Date());
             this.updateById(file);

biji-houdaun/src/main/java/com/test/bijihoudaun/service/impl/RegistrationCodeServiceImpl.java

@@ -1,5 +1,6 @@
 package com.test.bijihoudaun.service.impl;
 
+import cn.hutool.core.util.ObjectUtil;
 import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
 import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
 import com.test.bijihoudaun.entity.RegistrationCode;
@@ -36,7 +37,7 @@ public class RegistrationCodeServiceImpl extends ServiceImpl<RegistrationCodeMap
         queryWrapper.eq("code", code);
         RegistrationCode registrationCode = getOne(queryWrapper);
 
-        if (registrationCode == null) {
+        if (ObjectUtil.isNull(registrationCode)) {
             return false;
         }
 

biji-houdaun/src/main/java/com/test/bijihoudaun/service/impl/SystemSettingServiceImpl.java

@@ -1,5 +1,6 @@
 package com.test.bijihoudaun.service.impl;
 
+import cn.hutool.core.util.ObjectUtil;
 import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
 import com.test.bijihoudaun.entity.SystemSetting;
 import com.test.bijihoudaun.mapper.SystemSettingMapper;
@@ -17,7 +18,7 @@ public class SystemSettingServiceImpl extends ServiceImpl<SystemSettingMapper, S
     public boolean isRegistrationEnabled() {
         SystemSetting setting = getById(REGISTRATION_ENABLED_KEY);
         // 默认开启注册
-        return setting == null || Boolean.parseBoolean(setting.getSettingValue());
+        return ObjectUtil.isNull(setting) || Boolean.parseBoolean(setting.getSettingValue());
     }
 
     @Override

biji-houdaun/src/main/java/com/test/bijihoudaun/service/impl/UserServiceImpl.java

@@ -1,5 +1,6 @@
 package com.test.bijihoudaun.service.impl;
 
+import cn.hutool.core.util.ObjectUtil;
 import com.baomidou.mybatisplus.core.conditions.query.LambdaQueryWrapper;
 
 import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
@@ -33,7 +34,7 @@ public class UserServiceImpl extends ServiceImpl<UserMapper, User> implements Us
     @Override
     public UserDetails loadUserByUsername(String username) throws UsernameNotFoundException {
         User user = userMapper.findByUsername(username);
-        if (user == null) {
+        if (ObjectUtil.isNull(user)) {
             throw new UsernameNotFoundException("User not found with username: " + username);
         }
         return new org.springframework.security.core.userdetails.User(user.getUsername(), user.getPassword(), new ArrayList<>());
@@ -85,13 +86,13 @@ public class UserServiceImpl extends ServiceImpl<UserMapper, User> implements Us
                 .eq(User::getToken, token);
         User user = getOne(queryWrapper);
         // 修改过期检查逻辑
-        return user != null && new Date().before(user.getTokenEnddata());
+        return ObjectUtil.isNotNull(user) && new Date().before(user.getTokenEnddata());
     }
 
     @Override
     public void updatePassword(Long userId, UpdatePasswordBo updatePasswordBo) {
         User user = getById(userId);
-        if (user == null) {
+        if (ObjectUtil.isNull(user)) {
             throw new BusinessException("用户不存在");
         }
         if (!PasswordUtils.verify(updatePasswordBo.getOldPassword(), user.getPassword())) {