```

feat(content): 添加内容服务参数验证和空值处理

- 在 CmsContentServiceImpl 中多个方法添加 Assert.notNull 参数验证
- 为 queryById、queryByIdWithPermission、update 等方法添加内容ID非空检查
- 处理点赞数为空时的默认值设置，避免空指针异常
- 在 controller 层修复注释参数名大小写问题
```

src/main/java/com/kexue/skills/controller/CmsContentController.java

@@ -2,6 +2,7 @@ package com.kexue.skills.controller;
 
 import com.github.pagehelper.PageInfo;
 import com.kexue.skills.annotation.RequireAuth;
+import com.kexue.skills.common.Assert;
 import com.kexue.skills.common.CommonResult;
 import com.kexue.skills.entity.CmsContent;
 import com.kexue.skills.entity.base.IdDto;
@@ -289,7 +290,7 @@ public class CmsContentController {
     /**
      * 获取CmsContent的content字段内容
      *
-     * @param QueryContentDto 包含contentId和languageType的DTO对象
+     * @param queryContentDto 包含contentId和languageType的DTO对象
      * @return content或contentEn字段的内容
      */
     @PostMapping("/getContent")

src/main/java/com/kexue/skills/service/impl/CmsContentServiceImpl.java

@@ -3,6 +3,7 @@ package com.kexue.skills.service.impl;
 import com.github.pagehelper.PageHelper;
 import com.github.pagehelper.PageInfo;
 import com.github.pagehelper.util.StringUtil;
+import com.kexue.skills.common.Assert;
 import com.kexue.skills.common.LoginUserCacheUtil;
 import com.kexue.skills.entity.CmsContent;
 import com.kexue.skills.entity.CmsContentView;
@@ -218,6 +219,7 @@ public class CmsContentServiceImpl implements CmsContentService {
      */
     @Override
     public CmsContent queryById(Long contentId) {
+        Assert.notNull(contentId, "内容ID不能为空");
         CmsContent content = this.cmsContentMapper.queryById(contentId);
         if (content == null) {
             return null;
@@ -265,6 +267,7 @@ public class CmsContentServiceImpl implements CmsContentService {
      * @return 实例对象
      */
     public CmsContent queryByIdWithPermission(Long contentId, Long userId) {
+        Assert.notNull(contentId, "内容ID不能为空");
         CmsContent content = this.cmsContentMapper.queryById(contentId);
         if (content == null) {
             return null;
@@ -324,6 +327,7 @@ public class CmsContentServiceImpl implements CmsContentService {
      */
     @Override
     public CmsContent update(CmsContent cmsContent) {
+        Assert.notNull(cmsContent.getContentId(), "内容ID不能为空");
         // 设置更新时间
         cmsContent.setUpdateTime(new Date());
         // 更新数据
@@ -344,6 +348,7 @@ public class CmsContentServiceImpl implements CmsContentService {
      */
     @Override
     public int updateAuditStatus(Long contentId, Integer auditStatus, Long reviewerId, String reviewerName, String auditComment, String updateBy) {
+        Assert.notNull(contentId, "内容ID不能为空");
         return this.cmsContentMapper.updateAuditStatus(contentId, auditStatus, reviewerId, reviewerName, auditComment, updateBy);
     }
 
@@ -358,6 +363,7 @@ public class CmsContentServiceImpl implements CmsContentService {
      */
     @Override
     public int updatePublishStatus(Long contentId, Integer publishStatus, String publishTime, String updateBy) {
+        Assert.notNull(contentId, "内容ID不能为空");
         return this.cmsContentMapper.updatePublishStatus(contentId, publishStatus, publishTime, updateBy);
     }
 
@@ -369,6 +375,7 @@ public class CmsContentServiceImpl implements CmsContentService {
      */
     @Override
     public int increaseViewCount(Long contentId) {
+        Assert.notNull(contentId, "内容ID不能为空");
         // 增加阅读量
         int result = this.cmsContentMapper.increaseViewCount(contentId);
         
@@ -393,6 +400,7 @@ public class CmsContentServiceImpl implements CmsContentService {
      */
     @Override
     public int logicDeleteById(Long contentId, String updateBy) {
+        Assert.notNull(contentId, "内容ID不能为空");
         return this.cmsContentMapper.logicDeleteById(contentId, updateBy);
     }
 
@@ -404,6 +412,7 @@ public class CmsContentServiceImpl implements CmsContentService {
      */
     @Override
     public int deleteById(Long contentId) {
+        Assert.notNull(contentId, "内容ID不能为空");
         return this.cmsContentMapper.deleteById(contentId);
     }
 
@@ -415,6 +424,7 @@ public class CmsContentServiceImpl implements CmsContentService {
      */
     @Override
     public int addFavorite(Long contentId) {
+        Assert.notNull(contentId, "内容ID不能为空");
         // 获取当前登录用户ID
         Long userId = Long.parseLong(StpUtil.getLoginId().toString());
         // 获取当前登录用户名
@@ -425,6 +435,9 @@ public class CmsContentServiceImpl implements CmsContentService {
         if (content == null) {
             return 0;
         }
+        if(Objects.isNull(content.getLikeCount())){
+            content.setLikeCount(0);
+        }
         
         // 检查用户是否已经收藏过该内容
         CmsContentLike existingLike = cmsContentLikeMapper.queryByUserIdAndContentId(userId, contentId);
@@ -475,6 +488,7 @@ public class CmsContentServiceImpl implements CmsContentService {
      */
     @Override
     public int removeFavorite(Long contentId) {
+        Assert.notNull(contentId, "内容ID不能为空");
         // 获取当前登录用户ID
         Long userId = Long.parseLong(StpUtil.getLoginId().toString());
         
@@ -513,6 +527,7 @@ public class CmsContentServiceImpl implements CmsContentService {
      */
     @Override
     public boolean isFavorited(Long contentId) {
+        Assert.notNull(contentId, "内容ID不能为空");
         try {
             // 获取当前登录用户ID
             Long userId = Long.parseLong(StpUtil.getLoginId().toString());
@@ -532,6 +547,7 @@ public class CmsContentServiceImpl implements CmsContentService {
      */
     @Override
     public int addView(Long contentId) {
+        Assert.notNull(contentId, "内容ID不能为空");
         try {
             // 获取当前登录用户ID
             Long userId = Long.parseLong(StpUtil.getLoginId().toString());
@@ -903,6 +919,7 @@ public class CmsContentServiceImpl implements CmsContentService {
     
     @Override
     public String getContent(Long contentId, Integer languageType) {
+        Assert.notNull(contentId, "内容ID不能为空");
         CmsContent cmsContent = this.cmsContentMapper.queryById(contentId);
         if (cmsContent == null) {
             return null;