diff --git a/src/main/java/run/halo/app/controller/content/ContentCategoryController.java b/src/main/java/run/halo/app/controller/content/ContentCategoryController.java
index e85fb98be..e713fd34a 100644
--- a/src/main/java/run/halo/app/controller/content/ContentCategoryController.java
+++ b/src/main/java/run/halo/app/controller/content/ContentCategoryController.java
@@ -85,7 +85,7 @@ public class ContentCategoryController {
                              @PathVariable("page") Integer page,
                              @SortDefault(sort = "createTime", direction = DESC) Sort sort) {
         // Get category by slug name
-        final Category category = categoryService.getBySlugName(slugName);
+        final Category category = categoryService.getBySlugNameOfNonNull(slugName);
 
         final Pageable pageable = PageRequest.of(page - 1, optionService.getPostPageSize(), sort);
         Page<Post> postPage = postCategoryService.pagePostBy(category.getId(), pageable);
diff --git a/src/main/java/run/halo/app/controller/content/api/CategoryController.java b/src/main/java/run/halo/app/controller/content/api/CategoryController.java
index 1be79ec43..be62bbdeb 100644
--- a/src/main/java/run/halo/app/controller/content/api/CategoryController.java
+++ b/src/main/java/run/halo/app/controller/content/api/CategoryController.java
@@ -58,7 +58,7 @@ public class CategoryController {
     public Page<BasePostSimpleDTO> listPostsBy(@PathVariable("slugName") String slugName,
                                                @PageableDefault(sort = "updateTime", direction = DESC) Pageable pageable) {
         // Get category by slug name
-        Category category = categoryService.getBySlugName(slugName);
+        Category category = categoryService.getBySlugNameOfNonNull(slugName);
 
         Page<Post> postPage = postCategoryService.pagePostBy(category.getId(), pageable);
         return postService.convertToSimple(postPage);
diff --git a/src/main/java/run/halo/app/service/AdminService.java b/src/main/java/run/halo/app/service/AdminService.java
index 5a489c291..d8f1b054f 100644
--- a/src/main/java/run/halo/app/service/AdminService.java
+++ b/src/main/java/run/halo/app/service/AdminService.java
@@ -7,11 +7,11 @@ import run.halo.app.model.params.LoginParam;
 import run.halo.app.security.token.AuthToken;
 
 /**
- * Admin service.
+ * Admin service interface.
  *
  * @author johnniang
  * @author ryanwang
- * @date 19-4-29
+ * @date 2019-04-29
  */
 public interface AdminService {
 
diff --git a/src/main/java/run/halo/app/service/AttachmentService.java b/src/main/java/run/halo/app/service/AttachmentService.java
index e98cf7bf2..3d8360348 100644
--- a/src/main/java/run/halo/app/service/AttachmentService.java
+++ b/src/main/java/run/halo/app/service/AttachmentService.java
@@ -17,6 +17,7 @@ import java.util.List;
  * Attachment service.
  *
  * @author johnniang
+ * @date : 2019-03-14
  */
 public interface AttachmentService extends CrudService<Attachment, Integer> {
 
diff --git a/src/main/java/run/halo/app/service/BackupService.java b/src/main/java/run/halo/app/service/BackupService.java
index 6426fa0c6..eefc8dccc 100644
--- a/src/main/java/run/halo/app/service/BackupService.java
+++ b/src/main/java/run/halo/app/service/BackupService.java
@@ -9,7 +9,7 @@ import java.io.IOException;
  * Backup service interface.
  *
  * @author johnniang
- * @date 19-4-26
+ * @date 2019-04-26
  */
 public interface BackupService {
 
diff --git a/src/main/java/run/halo/app/service/CategoryService.java b/src/main/java/run/halo/app/service/CategoryService.java
index 7de4e678f..130c291e1 100755
--- a/src/main/java/run/halo/app/service/CategoryService.java
+++ b/src/main/java/run/halo/app/service/CategoryService.java
@@ -15,6 +15,8 @@ import java.util.List;
  * Category service.
  *
  * @author johnniang
+ * @author ryanwang
+ * @date : 2019-03-14
  */
 public interface CategoryService extends CrudService<Category, Integer> {
 
@@ -36,6 +38,15 @@ public interface CategoryService extends CrudService<Category, Integer> {
     @NonNull
     Category getBySlugName(@NonNull String slugName);
 
+    /**
+     * Get category by slug name
+     *
+     * @param slugName slug name
+     * @return Category
+     */
+    @NonNull
+    Category getBySlugNameOfNonNull(String slugName);
+
     /**
      * Get Category by name.
      *
diff --git a/src/main/java/run/halo/app/service/JournalCommentService.java b/src/main/java/run/halo/app/service/JournalCommentService.java
index 2267c964c..3adb1a44f 100644
--- a/src/main/java/run/halo/app/service/JournalCommentService.java
+++ b/src/main/java/run/halo/app/service/JournalCommentService.java
@@ -13,7 +13,7 @@ import java.util.List;
  * Journal comment service interface.
  *
  * @author johnniang
- * @date 19-4-25
+ * @date 2019-04-25
  */
 public interface JournalCommentService extends BaseCommentService<JournalComment> {
 
diff --git a/src/main/java/run/halo/app/service/JournalService.java b/src/main/java/run/halo/app/service/JournalService.java
index 4194e92ed..080ab6068 100644
--- a/src/main/java/run/halo/app/service/JournalService.java
+++ b/src/main/java/run/halo/app/service/JournalService.java
@@ -18,7 +18,7 @@ import java.util.List;
  *
  * @author johnniang
  * @author ryanwang
- * @date 19-4-24
+ * @date 2019-04-24
  */
 public interface JournalService extends CrudService<Journal, Integer> {
 
diff --git a/src/main/java/run/halo/app/service/LinkService.java b/src/main/java/run/halo/app/service/LinkService.java
index de2d9591b..da03d9cdb 100755
--- a/src/main/java/run/halo/app/service/LinkService.java
+++ b/src/main/java/run/halo/app/service/LinkService.java
@@ -11,9 +11,10 @@ import run.halo.app.service.base.CrudService;
 import java.util.List;
 
 /**
- * Link service.
+ * Link service interface.
  *
  * @author johnniang
+ * @date 2019-03-14
  */
 public interface LinkService extends CrudService<Link, Integer> {
 
diff --git a/src/main/java/run/halo/app/service/LogService.java b/src/main/java/run/halo/app/service/LogService.java
index 5e93127cc..7b3405670 100644
--- a/src/main/java/run/halo/app/service/LogService.java
+++ b/src/main/java/run/halo/app/service/LogService.java
@@ -6,9 +6,10 @@ import run.halo.app.model.entity.Log;
 import run.halo.app.service.base.CrudService;
 
 /**
- * Log service.
+ * Log service interface.
  *
  * @author johnniang
+ * @date 2019-03-14
  */
 public interface LogService extends CrudService<Log, Long> {
 
diff --git a/src/main/java/run/halo/app/service/MailService.java b/src/main/java/run/halo/app/service/MailService.java
index 4c109dbb9..5d6dc5d13 100644
--- a/src/main/java/run/halo/app/service/MailService.java
+++ b/src/main/java/run/halo/app/service/MailService.java
@@ -3,10 +3,10 @@ package run.halo.app.service;
 import java.util.Map;
 
 /**
- * Mail server
+ * Mail service interface.
  *
  * @author ryanwang
- * @date : 2019-03-17
+ * @date 2019-03-17
  */
 public interface MailService {
 
diff --git a/src/main/java/run/halo/app/service/MenuService.java b/src/main/java/run/halo/app/service/MenuService.java
index 8f099d8e1..72135eef3 100644
--- a/src/main/java/run/halo/app/service/MenuService.java
+++ b/src/main/java/run/halo/app/service/MenuService.java
@@ -11,10 +11,11 @@ import run.halo.app.service.base.CrudService;
 import java.util.List;
 
 /**
- * Menu service.
+ * Menu service interface.
  *
  * @author johnniang
  * @author ryanwang
+ * @date 2019-03-14
  */
 public interface MenuService extends CrudService<Menu, Integer> {
 
diff --git a/src/main/java/run/halo/app/service/OptionService.java b/src/main/java/run/halo/app/service/OptionService.java
index 5658acd21..7f7c49389 100755
--- a/src/main/java/run/halo/app/service/OptionService.java
+++ b/src/main/java/run/halo/app/service/OptionService.java
@@ -18,9 +18,10 @@ import java.util.Map;
 import java.util.Optional;
 
 /**
- * Option service.
+ * Option service interface.
  *
  * @author johnniang
+ * @date 2019-03-14
  */
 public interface OptionService extends CrudService<Option, Integer> {
 
diff --git a/src/main/java/run/halo/app/service/PhotoService.java b/src/main/java/run/halo/app/service/PhotoService.java
index 88e2008d0..fb3759fdd 100644
--- a/src/main/java/run/halo/app/service/PhotoService.java
+++ b/src/main/java/run/halo/app/service/PhotoService.java
@@ -14,9 +14,10 @@ import run.halo.app.service.base.CrudService;
 import java.util.List;
 
 /**
- * Photo service.
+ * Photo service interface.
  *
  * @author johnniang
+ * @date 2019-03-14
  */
 public interface PhotoService extends CrudService<Photo, Integer> {
 
diff --git a/src/main/java/run/halo/app/service/PostCategoryService.java b/src/main/java/run/halo/app/service/PostCategoryService.java
index 9fb73b584..0f7908eca 100644
--- a/src/main/java/run/halo/app/service/PostCategoryService.java
+++ b/src/main/java/run/halo/app/service/PostCategoryService.java
@@ -21,7 +21,7 @@ import java.util.Set;
  * Post category service interface.
  *
  * @author johnniang
- * @date 3/19/19
+ * @date 2019-03-19
  */
 public interface PostCategoryService extends CrudService<PostCategory, Integer> {
 
diff --git a/src/main/java/run/halo/app/service/PostCommentService.java b/src/main/java/run/halo/app/service/PostCommentService.java
index a0e55c3b1..a55c09a03 100644
--- a/src/main/java/run/halo/app/service/PostCommentService.java
+++ b/src/main/java/run/halo/app/service/PostCommentService.java
@@ -12,9 +12,10 @@ import run.halo.app.service.base.BaseCommentService;
 import java.util.List;
 
 /**
- * PostComment service.
+ * Post comment service interface.
  *
  * @author johnniang
+ * @date 2019-03-14
  */
 public interface PostCommentService extends BaseCommentService<PostComment> {
 
diff --git a/src/main/java/run/halo/app/service/PostService.java b/src/main/java/run/halo/app/service/PostService.java
index 8368fef2a..bedf523c3 100755
--- a/src/main/java/run/halo/app/service/PostService.java
+++ b/src/main/java/run/halo/app/service/PostService.java
@@ -17,10 +17,11 @@ import java.util.List;
 import java.util.Set;
 
 /**
- * Post service.
+ * Post service interface.
  *
  * @author johnniang
  * @author ryanwang
+ * @date 2019-03-14
  */
 public interface PostService extends BasePostService<Post> {
 
diff --git a/src/main/java/run/halo/app/service/PostTagService.java b/src/main/java/run/halo/app/service/PostTagService.java
index deb2194cb..8cfb8e770 100644
--- a/src/main/java/run/halo/app/service/PostTagService.java
+++ b/src/main/java/run/halo/app/service/PostTagService.java
@@ -21,7 +21,7 @@ import java.util.Set;
  * Post tag service interface.
  *
  * @author johnniang
- * @date 3/19/19
+ * @date 2019-03-19
  */
 public interface PostTagService extends CrudService<PostTag, Integer> {
 
diff --git a/src/main/java/run/halo/app/service/RecoveryService.java b/src/main/java/run/halo/app/service/RecoveryService.java
index e4ace0e75..0a495a376 100644
--- a/src/main/java/run/halo/app/service/RecoveryService.java
+++ b/src/main/java/run/halo/app/service/RecoveryService.java
@@ -7,7 +7,7 @@ import org.springframework.web.multipart.MultipartFile;
  * Recovery service interface.
  *
  * @author johnniang
- * @date 19-4-26
+ * @date 2019-04-26
  */
 public interface RecoveryService {
 
diff --git a/src/main/java/run/halo/app/service/SheetCommentService.java b/src/main/java/run/halo/app/service/SheetCommentService.java
index a63df91da..dea4a1931 100644
--- a/src/main/java/run/halo/app/service/SheetCommentService.java
+++ b/src/main/java/run/halo/app/service/SheetCommentService.java
@@ -13,7 +13,7 @@ import java.util.List;
  * Sheet comment service interface.
  *
  * @author johnniang
- * @date 19-4-24
+ * @date 2019-04-24
  */
 public interface SheetCommentService extends BaseCommentService<SheetComment> {
 
diff --git a/src/main/java/run/halo/app/service/SheetService.java b/src/main/java/run/halo/app/service/SheetService.java
index 5e0b206d0..be3bbb26e 100644
--- a/src/main/java/run/halo/app/service/SheetService.java
+++ b/src/main/java/run/halo/app/service/SheetService.java
@@ -15,7 +15,7 @@ import java.util.List;
  *
  * @author johnniang
  * @author ryanwang
- * @date 19-4-24
+ * @date 2019-04-24
  */
 public interface SheetService extends BasePostService<Sheet> {
 
diff --git a/src/main/java/run/halo/app/service/TagService.java b/src/main/java/run/halo/app/service/TagService.java
index afd05df33..d9d1e02a1 100644
--- a/src/main/java/run/halo/app/service/TagService.java
+++ b/src/main/java/run/halo/app/service/TagService.java
@@ -8,11 +8,12 @@ import run.halo.app.service.base.CrudService;
 
 import java.util.List;
 
-
 /**
- * Tag service.
+ * Tag service interface.
  *
  * @author johnniang
+ * @author ryanwang
+ * @date 2019-03-14
  */
 public interface TagService extends CrudService<Tag, Integer> {
 
@@ -25,6 +26,15 @@ public interface TagService extends CrudService<Tag, Integer> {
     @NonNull
     Tag getBySlugNameOfNonNull(@NonNull String slugName);
 
+    /**
+     * Get tag by slug name
+     *
+     * @param slugName slug name
+     * @return tag
+     */
+    @NonNull
+    Tag getBySlugName(@NonNull String slugName);
+
     /**
      * Get tag by tag name.
      *
diff --git a/src/main/java/run/halo/app/service/ThemeService.java b/src/main/java/run/halo/app/service/ThemeService.java
index 1835e835d..6ad65d68d 100644
--- a/src/main/java/run/halo/app/service/ThemeService.java
+++ b/src/main/java/run/halo/app/service/ThemeService.java
@@ -14,8 +14,10 @@ import java.util.Optional;
 import java.util.Set;
 
 /**
+ * Theme service interface.
+ *
  * @author ryanwang
- * @date : 2019/3/26
+ * @date 2019-03-26
  */
 public interface ThemeService {
 
diff --git a/src/main/java/run/halo/app/service/ThemeSettingService.java b/src/main/java/run/halo/app/service/ThemeSettingService.java
index 7cdd35404..bec2c5af1 100644
--- a/src/main/java/run/halo/app/service/ThemeSettingService.java
+++ b/src/main/java/run/halo/app/service/ThemeSettingService.java
@@ -12,7 +12,7 @@ import java.util.Map;
  * Theme setting service interface.
  *
  * @author johnniang
- * @date 4/8/19
+ * @date 2019-04-08
  */
 public interface ThemeSettingService {
 
diff --git a/src/main/java/run/halo/app/service/TraceService.java b/src/main/java/run/halo/app/service/TraceService.java
index 586041b89..915152a33 100644
--- a/src/main/java/run/halo/app/service/TraceService.java
+++ b/src/main/java/run/halo/app/service/TraceService.java
@@ -9,7 +9,7 @@ import java.util.List;
  * Trace service interface.
  *
  * @author johnniang
- * @date 19-6-18
+ * @date 2019-06-18
  */
 public interface TraceService {
 
diff --git a/src/main/java/run/halo/app/service/UserService.java b/src/main/java/run/halo/app/service/UserService.java
index ec5c4bab4..3f2563fd4 100755
--- a/src/main/java/run/halo/app/service/UserService.java
+++ b/src/main/java/run/halo/app/service/UserService.java
@@ -11,9 +11,10 @@ import run.halo.app.service.base.CrudService;
 import java.util.Optional;
 
 /**
- * User service.
+ * User service interface.
  *
  * @author johnniang
+ * @date 2019-03-14
  */
 public interface UserService extends CrudService<User, Integer> {
 
diff --git a/src/main/java/run/halo/app/service/impl/AdminServiceImpl.java b/src/main/java/run/halo/app/service/impl/AdminServiceImpl.java
index c21ea412c..801150360 100644
--- a/src/main/java/run/halo/app/service/impl/AdminServiceImpl.java
+++ b/src/main/java/run/halo/app/service/impl/AdminServiceImpl.java
@@ -51,7 +51,7 @@ import static run.halo.app.model.support.HaloConst.*;
  *
  * @author johnniang
  * @author ryanwang
- * @date 19-4-29
+ * @date 2019-04-29
  */
 @Slf4j
 @Service
diff --git a/src/main/java/run/halo/app/service/impl/AttachmentServiceImpl.java b/src/main/java/run/halo/app/service/impl/AttachmentServiceImpl.java
index 86715c4e2..feb5c7ddb 100644
--- a/src/main/java/run/halo/app/service/impl/AttachmentServiceImpl.java
+++ b/src/main/java/run/halo/app/service/impl/AttachmentServiceImpl.java
@@ -32,6 +32,7 @@ import java.util.Objects;
  * AttachmentService implementation
  *
  * @author ryanwang
+ * @author johnniang
  * @date : 2019-03-14
  */
 @Slf4j
diff --git a/src/main/java/run/halo/app/service/impl/BackupServiceImpl.java b/src/main/java/run/halo/app/service/impl/BackupServiceImpl.java
index 483b6308a..ed9133bf7 100644
--- a/src/main/java/run/halo/app/service/impl/BackupServiceImpl.java
+++ b/src/main/java/run/halo/app/service/impl/BackupServiceImpl.java
@@ -14,7 +14,7 @@ import java.nio.charset.StandardCharsets;
  * Backup service implementation.
  *
  * @author johnniang
- * @date 19-4-26
+ * @date 2019-04-26
  */
 @Service
 public class BackupServiceImpl implements BackupService {
diff --git a/src/main/java/run/halo/app/service/impl/BaseCommentServiceImpl.java b/src/main/java/run/halo/app/service/impl/BaseCommentServiceImpl.java
index 860019d77..14c030324 100644
--- a/src/main/java/run/halo/app/service/impl/BaseCommentServiceImpl.java
+++ b/src/main/java/run/halo/app/service/impl/BaseCommentServiceImpl.java
@@ -51,7 +51,7 @@ import java.util.stream.Collectors;
  * Base comment service implementation.
  *
  * @author johnniang
- * @date 19-4-24
+ * @date 2019-04-24
  */
 @Slf4j
 public abstract class BaseCommentServiceImpl<COMMENT extends BaseComment> extends AbstractCrudService<COMMENT, Long> implements BaseCommentService<COMMENT> {
diff --git a/src/main/java/run/halo/app/service/impl/BasePostServiceImpl.java b/src/main/java/run/halo/app/service/impl/BasePostServiceImpl.java
index 7e9d05435..b58d17f78 100644
--- a/src/main/java/run/halo/app/service/impl/BasePostServiceImpl.java
+++ b/src/main/java/run/halo/app/service/impl/BasePostServiceImpl.java
@@ -40,7 +40,7 @@ import static org.springframework.data.domain.Sort.Direction.DESC;
  * Base post service implementation.
  *
  * @author johnniang
- * @date 19-4-24
+ * @date 2019-04-24
  */
 @Slf4j
 public abstract class BasePostServiceImpl<POST extends BasePost> extends AbstractCrudService<POST, Integer> implements BasePostService<POST> {
diff --git a/src/main/java/run/halo/app/service/impl/CategoryServiceImpl.java b/src/main/java/run/halo/app/service/impl/CategoryServiceImpl.java
index c66bf0b8a..647620a37 100644
--- a/src/main/java/run/halo/app/service/impl/CategoryServiceImpl.java
+++ b/src/main/java/run/halo/app/service/impl/CategoryServiceImpl.java
@@ -24,9 +24,10 @@ import java.util.List;
 import java.util.stream.Collectors;
 
 /**
- * CategoryService implementation class
+ * CategoryService implementation class.
  *
  * @author ryanwang
+ * @author johnniang
  * @date : 2019-03-14
  */
 @Slf4j
@@ -146,7 +147,12 @@ public class CategoryServiceImpl extends AbstractCrudService<Category, Integer>
 
     @Override
     public Category getBySlugName(String slugName) {
-        return categoryRepository.getBySlugName(slugName).orElseThrow(() -> new NotFoundException("该分类已存在").setErrorData(slugName));
+        return categoryRepository.getBySlugName(slugName).orElse(null);
+    }
+
+    @Override
+    public Category getBySlugNameOfNonNull(String slugName) {
+        return categoryRepository.getBySlugName(slugName).orElseThrow(() -> new NotFoundException("该分类不存在").setErrorData(slugName));
     }
 
     @Override
diff --git a/src/main/java/run/halo/app/service/impl/JournalCommentServiceImpl.java b/src/main/java/run/halo/app/service/impl/JournalCommentServiceImpl.java
index 7c54da67f..25928445a 100644
--- a/src/main/java/run/halo/app/service/impl/JournalCommentServiceImpl.java
+++ b/src/main/java/run/halo/app/service/impl/JournalCommentServiceImpl.java
@@ -28,7 +28,7 @@ import java.util.stream.Collectors;
  * Journal comment service implementation.
  *
  * @author johnniang
- * @date 19-4-25
+ * @date 2019-04-25
  */
 @Service
 public class JournalCommentServiceImpl extends BaseCommentServiceImpl<JournalComment> implements JournalCommentService {
diff --git a/src/main/java/run/halo/app/service/impl/JournalServiceImpl.java b/src/main/java/run/halo/app/service/impl/JournalServiceImpl.java
index f974905f4..33b00fc29 100644
--- a/src/main/java/run/halo/app/service/impl/JournalServiceImpl.java
+++ b/src/main/java/run/halo/app/service/impl/JournalServiceImpl.java
@@ -29,7 +29,7 @@ import java.util.stream.Collectors;
  *
  * @author johnniang
  * @author ryanwang
- * @date 19-4-24
+ * @date 2019-04-24
  */
 @Service
 public class JournalServiceImpl extends AbstractCrudService<Journal, Integer> implements JournalService {
diff --git a/src/main/java/run/halo/app/service/impl/LinkServiceImpl.java b/src/main/java/run/halo/app/service/impl/LinkServiceImpl.java
index b8affa596..20aa67d9f 100644
--- a/src/main/java/run/halo/app/service/impl/LinkServiceImpl.java
+++ b/src/main/java/run/halo/app/service/impl/LinkServiceImpl.java
@@ -24,7 +24,7 @@ import java.util.stream.Collectors;
  * LinkService implementation class
  *
  * @author ryanwang
- * @date : 2019-03-14
+ * @date 2019-03-14
  */
 @Service
 public class LinkServiceImpl extends AbstractCrudService<Link, Integer> implements LinkService {
diff --git a/src/main/java/run/halo/app/service/impl/LogServiceImpl.java b/src/main/java/run/halo/app/service/impl/LogServiceImpl.java
index 087c8de1b..086e23674 100644
--- a/src/main/java/run/halo/app/service/impl/LogServiceImpl.java
+++ b/src/main/java/run/halo/app/service/impl/LogServiceImpl.java
@@ -15,7 +15,7 @@ import run.halo.app.service.base.AbstractCrudService;
  * LogService implementation class
  *
  * @author ryanwang
- * @date : 2019-03-14
+ * @date 2019-03-14
  */
 @Service
 public class LogServiceImpl extends AbstractCrudService<Log, Long> implements LogService {
diff --git a/src/main/java/run/halo/app/service/impl/MailServiceImpl.java b/src/main/java/run/halo/app/service/impl/MailServiceImpl.java
index 646c362e8..a2d58ca79 100644
--- a/src/main/java/run/halo/app/service/impl/MailServiceImpl.java
+++ b/src/main/java/run/halo/app/service/impl/MailServiceImpl.java
@@ -20,7 +20,7 @@ import java.util.Properties;
  * Mail service implementation.
  *
  * @author ryanwang
- * @date : 2019-03-17
+ * @date 2019-03-17
  */
 @Slf4j
 @Service
diff --git a/src/main/java/run/halo/app/service/impl/MenuServiceImpl.java b/src/main/java/run/halo/app/service/impl/MenuServiceImpl.java
index 67bb25df5..29aa71f65 100644
--- a/src/main/java/run/halo/app/service/impl/MenuServiceImpl.java
+++ b/src/main/java/run/halo/app/service/impl/MenuServiceImpl.java
@@ -21,10 +21,10 @@ import java.util.List;
 import java.util.stream.Collectors;
 
 /**
- * MenuService implementation class
+ * MenuService implementation class.
  *
  * @author ryanwang
- * @date : 2019-03-14
+ * @date 2019-03-14
  */
 @Service
 public class MenuServiceImpl extends AbstractCrudService<Menu, Integer> implements MenuService {
diff --git a/src/main/java/run/halo/app/service/impl/OptionServiceImpl.java b/src/main/java/run/halo/app/service/impl/OptionServiceImpl.java
index 6ee06ff78..cb0966039 100644
--- a/src/main/java/run/halo/app/service/impl/OptionServiceImpl.java
+++ b/src/main/java/run/halo/app/service/impl/OptionServiceImpl.java
@@ -30,7 +30,7 @@ import java.util.*;
  * OptionService implementation class
  *
  * @author ryanwang
- * @date : 2019-03-14
+ * @date 2019-03-14
  */
 @Slf4j
 @Service
diff --git a/src/main/java/run/halo/app/service/impl/PhotoServiceImpl.java b/src/main/java/run/halo/app/service/impl/PhotoServiceImpl.java
index 35e0749c2..f3f82a1c2 100644
--- a/src/main/java/run/halo/app/service/impl/PhotoServiceImpl.java
+++ b/src/main/java/run/halo/app/service/impl/PhotoServiceImpl.java
@@ -29,7 +29,7 @@ import java.util.stream.Collectors;
  * PhotoService implementation class
  *
  * @author ryanwang
- * @date : 2019-03-14
+ * @date 2019-03-14
  */
 @Service
 public class PhotoServiceImpl extends AbstractCrudService<Photo, Integer> implements PhotoService {
diff --git a/src/main/java/run/halo/app/service/impl/PostCategoryServiceImpl.java b/src/main/java/run/halo/app/service/impl/PostCategoryServiceImpl.java
index 90ce4d109..a60f6b2bf 100644
--- a/src/main/java/run/halo/app/service/impl/PostCategoryServiceImpl.java
+++ b/src/main/java/run/halo/app/service/impl/PostCategoryServiceImpl.java
@@ -25,7 +25,7 @@ import java.util.stream.Collectors;
  * Post category service implementation.
  *
  * @author johnniang
- * @date 3/19/19
+ * @date 2019-03-19
  */
 @Service
 public class PostCategoryServiceImpl extends AbstractCrudService<PostCategory, Integer> implements PostCategoryService {
diff --git a/src/main/java/run/halo/app/service/impl/PostCommentServiceImpl.java b/src/main/java/run/halo/app/service/impl/PostCommentServiceImpl.java
index 1b729dd8e..670fab69a 100644
--- a/src/main/java/run/halo/app/service/impl/PostCommentServiceImpl.java
+++ b/src/main/java/run/halo/app/service/impl/PostCommentServiceImpl.java
@@ -32,7 +32,8 @@ import java.util.stream.Collectors;
  * PostCommentService implementation class
  *
  * @author ryanwang
- * @date : 2019-03-14
+ * @author johnniang
+ * @date 2019-03-14
  */
 @Slf4j
 @Service
diff --git a/src/main/java/run/halo/app/service/impl/PostServiceImpl.java b/src/main/java/run/halo/app/service/impl/PostServiceImpl.java
index d5c81bf31..7493bfa89 100644
--- a/src/main/java/run/halo/app/service/impl/PostServiceImpl.java
+++ b/src/main/java/run/halo/app/service/impl/PostServiceImpl.java
@@ -45,6 +45,7 @@ import static org.springframework.data.domain.Sort.Direction.DESC;
  *
  * @author johnniang
  * @author ryanwang
+ * @date 2019-03-14
  */
 @Slf4j
 @Service
diff --git a/src/main/java/run/halo/app/service/impl/PostTagServiceImpl.java b/src/main/java/run/halo/app/service/impl/PostTagServiceImpl.java
index 67c2141e0..2effa4284 100644
--- a/src/main/java/run/halo/app/service/impl/PostTagServiceImpl.java
+++ b/src/main/java/run/halo/app/service/impl/PostTagServiceImpl.java
@@ -25,7 +25,7 @@ import java.util.stream.Collectors;
  * Post tag service implementation.
  *
  * @author johnniang
- * @date 3/19/19
+ * @date 2019-03-19
  */
 @Service
 public class PostTagServiceImpl extends AbstractCrudService<PostTag, Integer> implements PostTagService {
diff --git a/src/main/java/run/halo/app/service/impl/RecoveryServiceImpl.java b/src/main/java/run/halo/app/service/impl/RecoveryServiceImpl.java
index 7199f55b0..ed63bb396 100644
--- a/src/main/java/run/halo/app/service/impl/RecoveryServiceImpl.java
+++ b/src/main/java/run/halo/app/service/impl/RecoveryServiceImpl.java
@@ -33,7 +33,8 @@ import java.util.stream.Collectors;
  * Recovery service implementation.
  *
  * @author johnniang
- * @date 19-4-26
+ * @author ryanwang
+ * @date 2019-04-26
  */
 @Slf4j
 @Service
@@ -64,6 +65,10 @@ public class RecoveryServiceImpl implements RecoveryService {
 
     private final PhotoService photoService;
 
+    private final PostCategoryService postCategoryService;
+
+    private final PostTagService postTagService;
+
     public RecoveryServiceImpl(AttachmentService attachmentService,
                                PostService postService,
                                LinkService linkService,
@@ -75,7 +80,9 @@ public class RecoveryServiceImpl implements RecoveryService {
                                SheetCommentService sheetCommentService,
                                SheetCommentRepository sheetCommentRepository,
                                SheetService sheetService,
-                               PhotoService photoService) {
+                               PhotoService photoService,
+                               PostCategoryService postCategoryService,
+                               PostTagService postTagService) {
         this.attachmentService = attachmentService;
         this.postService = postService;
         this.linkService = linkService;
@@ -88,6 +95,8 @@ public class RecoveryServiceImpl implements RecoveryService {
         this.sheetCommentRepository = sheetCommentRepository;
         this.sheetService = sheetService;
         this.photoService = photoService;
+        this.postCategoryService = postCategoryService;
+        this.postTagService = postTagService;
     }
 
     @Override
@@ -215,12 +224,20 @@ public class RecoveryServiceImpl implements RecoveryService {
         Post createdPost = postService.createOrUpdateBy(post);
 
         Object commentsObject = postMap.get("comments");
+        Object categoriesObject = postMap.get("categories");
+        Object tagsObject = postMap.get("tags");
         // Handle comments
         List<BaseComment> baseComments = handleComment(commentsObject, createdPost.getId());
 
-        // TODO Handle categories
+        // Handle categories
+        List<Category> categories = handleCategories(categoriesObject, createdPost.getId());
 
-        // TODO Handle tags
+        log.debug("Migrated categories of post [{}]: [{}]", categories, createdPost.getId());
+
+        // Handle tags
+        List<Tag> tags = handleTags(tagsObject, createdPost.getId());
+
+        log.debug("Migrated tags of post [{}]: [{}]", tags, createdPost.getId());
 
         List<PostComment> postComments = baseComments.stream()
                 .map(baseComment -> BeanUtils.transformFrom(baseComment, PostComment.class))
@@ -376,6 +393,96 @@ public class RecoveryServiceImpl implements RecoveryService {
         return result;
     }
 
+    @NonNull
+    private List<Category> handleCategories(@Nullable Object categoriesObject, @NonNull Integer postId) {
+        Assert.notNull(postId, "Post id must not be null");
+
+        if (!(categoriesObject instanceof List)) {
+            return Collections.emptyList();
+        }
+
+        List<Object> categoryObjectList = (List<Object>) categoriesObject;
+
+        List<Category> result = new LinkedList<>();
+
+        categoryObjectList.forEach(categoryObject -> {
+            if (!(categoryObject instanceof Map)) {
+                return;
+            }
+
+            Map<String, Object> categoryMap = (Map<String, Object>) categoryObject;
+
+            String slugName = categoryMap.getOrDefault("cateUrl", "").toString();
+
+            Category category = categoryService.getBySlugName(slugName);
+
+            if (null == category) {
+                category = new Category();
+                category.setName(categoryMap.getOrDefault("cateName", "").toString());
+                category.setSlugName(slugName);
+                category.setDescription(categoryMap.getOrDefault("cateDesc", "").toString());
+                category = categoryService.create(category);
+            }
+
+            PostCategory postCategory = new PostCategory();
+            postCategory.setCategoryId(category.getId());
+            postCategory.setPostId(postId);
+            postCategoryService.create(postCategory);
+
+            try {
+                result.add(category);
+            } catch (Exception e) {
+                log.warn("Failed to migrate a category", e);
+            }
+        });
+
+        return result;
+    }
+
+    @NonNull
+    private List<Tag> handleTags(@Nullable Object tagsObject, @NonNull Integer postId) {
+        Assert.notNull(postId, "Post id must not be null");
+
+        if (!(tagsObject instanceof List)) {
+            return Collections.emptyList();
+        }
+
+        List<Object> tagObjectList = (List<Object>) tagsObject;
+
+        List<Tag> result = new LinkedList<>();
+
+        tagObjectList.forEach(tagObject -> {
+            if (!(tagObject instanceof Map)) {
+                return;
+            }
+
+            Map<String, Object> tagMap = (Map<String, Object>) tagObject;
+
+            String slugName = tagMap.getOrDefault("tagUrl", "").toString();
+
+            Tag tag = tagService.getBySlugName(slugName);
+
+            if (null == tag) {
+                tag = new Tag();
+                tag.setName(tagMap.getOrDefault("tagName", "").toString());
+                tag.setSlugName(slugName);
+                tag = tagService.create(tag);
+            }
+
+            PostTag postTag = new PostTag();
+            postTag.setTagId(tag.getId());
+            postTag.setPostId(postId);
+            postTagService.create(postTag);
+
+            try {
+                result.add(tag);
+            } catch (Exception e) {
+                log.warn("Failed to migrate a tag", e);
+            }
+        });
+
+        return result;
+    }
 
     @NonNull
     private List<Menu> handleMenus(@Nullable Object menusObject) {
diff --git a/src/main/java/run/halo/app/service/impl/SheetCommentServiceImpl.java b/src/main/java/run/halo/app/service/impl/SheetCommentServiceImpl.java
index 17f4fdd50..34e4e1c0a 100644
--- a/src/main/java/run/halo/app/service/impl/SheetCommentServiceImpl.java
+++ b/src/main/java/run/halo/app/service/impl/SheetCommentServiceImpl.java
@@ -29,7 +29,7 @@ import java.util.stream.Collectors;
  * Sheet comment service implementation.
  *
  * @author johnniang
- * @date 19-4-24
+ * @date 2019-04-24
  */
 @Service
 public class SheetCommentServiceImpl extends BaseCommentServiceImpl<SheetComment> implements SheetCommentService {
diff --git a/src/main/java/run/halo/app/service/impl/SheetServiceImpl.java b/src/main/java/run/halo/app/service/impl/SheetServiceImpl.java
index 085eab05c..ddb5f9e32 100644
--- a/src/main/java/run/halo/app/service/impl/SheetServiceImpl.java
+++ b/src/main/java/run/halo/app/service/impl/SheetServiceImpl.java
@@ -31,7 +31,7 @@ import java.util.Set;
  *
  * @author johnniang
  * @author ryanwang
- * @date 19-4-24
+ * @date 2019-04-24
  */
 @Service
 public class SheetServiceImpl extends BasePostServiceImpl<Sheet> implements SheetService {
diff --git a/src/main/java/run/halo/app/service/impl/TagServiceImpl.java b/src/main/java/run/halo/app/service/impl/TagServiceImpl.java
index b783a73fc..a8f46fcae 100644
--- a/src/main/java/run/halo/app/service/impl/TagServiceImpl.java
+++ b/src/main/java/run/halo/app/service/impl/TagServiceImpl.java
@@ -17,10 +17,11 @@ import java.util.List;
 import java.util.stream.Collectors;
 
 /**
- * TagService implementation class
+ * TagService implementation class.
  *
+ * @author johnniang
  * @author ryanwang
- * @date : 2019-03-14
+ * @date 2019-03-14
  */
 @Slf4j
 @Service
@@ -51,9 +52,13 @@ public class TagServiceImpl extends AbstractCrudService<Tag, Integer> implements
 
     @Override
     public Tag getBySlugNameOfNonNull(String slugName) {
-        return tagRepository.getBySlugName(slugName).orElseThrow(() -> new NotFoundException("该标签已存在").setErrorData(slugName));
+        return tagRepository.getBySlugName(slugName).orElseThrow(() -> new NotFoundException("该标签不存在").setErrorData(slugName));
     }
 
+    @Override
+    public Tag getBySlugName(String slugName) {
+        return tagRepository.getBySlugName(slugName).orElse(null);
+    }
 
     @Override
     public Tag getByName(String name) {
diff --git a/src/main/java/run/halo/app/service/impl/ThemeServiceImpl.java b/src/main/java/run/halo/app/service/impl/ThemeServiceImpl.java
index 6ec4673ff..9c61f8ab5 100644
--- a/src/main/java/run/halo/app/service/impl/ThemeServiceImpl.java
+++ b/src/main/java/run/halo/app/service/impl/ThemeServiceImpl.java
@@ -53,7 +53,7 @@ import static run.halo.app.model.support.HaloConst.DEFAULT_THEME_ID;
  * Theme service implementation.
  *
  * @author ryanwang
- * @date : 2019/3/26
+ * @date 2019-03-26
  */
 @Slf4j
 @Service
diff --git a/src/main/java/run/halo/app/service/impl/ThemeSettingServiceImpl.java b/src/main/java/run/halo/app/service/impl/ThemeSettingServiceImpl.java
index b9f5cd0b5..6460468ba 100644
--- a/src/main/java/run/halo/app/service/impl/ThemeSettingServiceImpl.java
+++ b/src/main/java/run/halo/app/service/impl/ThemeSettingServiceImpl.java
@@ -24,7 +24,7 @@ import java.util.*;
  * Theme setting service implementation.
  *
  * @author johnniang
- * @date 4/8/19
+ * @date 2019-04-08
  */
 @Slf4j
 @Service
diff --git a/src/main/java/run/halo/app/service/impl/TraceServiceImpl.java b/src/main/java/run/halo/app/service/impl/TraceServiceImpl.java
index abaee5cb6..0304eaa8d 100644
--- a/src/main/java/run/halo/app/service/impl/TraceServiceImpl.java
+++ b/src/main/java/run/halo/app/service/impl/TraceServiceImpl.java
@@ -2,18 +2,16 @@ package run.halo.app.service.impl;
 
 import org.springframework.boot.actuate.trace.http.HttpTrace;
 import org.springframework.boot.actuate.trace.http.HttpTraceRepository;
-import org.springframework.data.domain.Page;
-import org.springframework.data.domain.PageImpl;
-import org.springframework.data.domain.Pageable;
 import org.springframework.stereotype.Service;
-import org.springframework.util.Assert;
 import run.halo.app.service.TraceService;
 
 import java.util.List;
 
 /**
+ * TraceService implementation class.
+ *
  * @author johnniang
- * @date 19-6-18
+ * @date 2019-06-18
  */
 @Service
 public class TraceServiceImpl implements TraceService {
diff --git a/src/main/java/run/halo/app/service/impl/UserServiceImpl.java b/src/main/java/run/halo/app/service/impl/UserServiceImpl.java
index 28879fe26..7905e1b14 100644
--- a/src/main/java/run/halo/app/service/impl/UserServiceImpl.java
+++ b/src/main/java/run/halo/app/service/impl/UserServiceImpl.java
@@ -31,10 +31,11 @@ import java.util.Optional;
 import java.util.concurrent.TimeUnit;
 
 /**
- * UserService implementation class
+ * UserService implementation class.
  *
  * @author ryanwang
- * @date : 2019-03-14
+ * @author johnniang
+ * @date 2019-03-14
  */
 @Service
 public class UserServiceImpl extends AbstractCrudService<User, Integer> implements UserService {