diff --git a/src/tree.py b/src/tree.py
index b770efcbed27862e46454c98fa75f23c00da153b..156e547da8071a7a04343cb3d0689542e0c0e57e 100644
--- a/src/tree.py
+++ b/src/tree.py
@@ -14,6 +14,7 @@ formatter = logging.Formatter('%(asctime)s - %(levelname)s - %(message)s')
 handler.setFormatter(formatter)
 logger.addHandler(handler)
 
+
 def load_json(p):
     with open(p, 'r') as f:
         return json.loads(f.read())
@@ -28,7 +29,7 @@ def dump_json(p, j, exist_ok=False, override=False):
             logger.error(f"{p} already exist")
             sys.exit(0)
 
-    with open(p, 'w+') as f:
+    with open(p, 'w+', encoding="utf8") as f:
         f.write(json.dumps(j, indent=2, ensure_ascii=False))
 
 
@@ -94,23 +95,39 @@ class TreeWalker:
         for index, level in enumerate(root_node["children"]):
             level_title = list(level.keys())[0]
             level_node = list(level.values())[0]
-            level_path = os.path.join(self.root, f"{index+1}.{level_title}")
+            level_path = os.path.join(self.root, f"{index + 1}.{level_title}")
             self.load_chapters(level_path, level_node)
             for index, chapter in enumerate(level_node["children"]):
                 chapter_title = list(chapter.keys())[0]
                 chapter_node = list(chapter.values())[0]
-                chapter_path = os.path.join(level_path, f"{index+1}.{chapter_title}")
+                chapter_path = os.path.join(level_path, f"{index + 1}.{chapter_title}")
                 self.load_sections(chapter_path, chapter_node)
                 for index, section_node in enumerate(chapter_node["children"]):
                     section_title = list(section_node.keys())[0]
-                    full_path = os.path.join(chapter_path, f"{index}.{section_title}")
+                    full_path = os.path.join(chapter_path, f"{index + 1}.{section_title}")
                     if os.path.isdir(full_path):
                         self.ensure_exercises(full_path)
+                        # TODO 四级知识点的处理仅为 Java 技能树的临时处理而设定，未来java技能树上线前会删掉这部分代码，将四级节点
+                        # 合并到三级节点
+                        for idx, [num, sub_section_title] in self.sort_dir_list([p for p in os.listdir(full_path)
+                                                                                 if os.path.isdir(os.path.join(full_path, p))]):
+                            order = idx + 1
+                            ensure_path = os.path.join(full_path, f"{order}.{sub_section_title}")
+                            forth_full_path = os.path.join(full_path, f"{num}.{sub_section_title}")
+                            if ensure_path != forth_full_path:
+                                os.rename(forth_full_path, ensure_path)
+                            if os.path.isdir(ensure_path):
+                                self.ensure_exercises(forth_full_path)
 
         tree_path = os.path.join(self.root, "tree.json")
         dump_json(tree_path, self.tree, exist_ok=True, override=True)
         return self.tree
 
+    def sort_dir_list(self, dirs):
+        result = [self.extract_node_env(dir) for dir in dirs]
+        result.sort(key=lambda item: item[0])
+        return result
+
     def load_levels(self, root_node):
         levels = []
         for level in os.listdir(self.root):
@@ -167,7 +184,7 @@ class TreeWalker:
         for index, [number, element] in enumerate(children):
             title = list(element.keys())[0]
             origin = os.path.join(base, f"{number}.{title}")
-            posted = os.path.join(base, f"{index+1}.{title}")
+            posted = os.path.join(base, f"{index + 1}.{title}")
             if origin != posted:
                 self.logger.info(f"rename [{origin}] to [{posted}]")
             os.rename(origin, posted)
@@ -229,8 +246,8 @@ class TreeWalker:
             config = {
                 "node_id": self.gen_node_id(),
                 "keywords": [],
-                "children":[],
-                "export":[]
+                "children": [],
+                "export": []
             }
             dump_json(config_path, config, exist_ok=True, override=True)
         else:
@@ -258,7 +275,8 @@ class TreeWalker:
             return int(number), title
         except Exception as error:
             self.logger.error(f"目录 [{path}] 解析失败，结构不合法，可能是缺少序号")
-            sys.exit(1)
+            # sys.exit(1)
+            raise error
 
     def load_chapter_node(self, full_name):
         config = self.ensure_chapter_config(full_name)
@@ -290,8 +308,8 @@ class TreeWalker:
         config = self.ensure_section_config(section_path)
         for e in config.get("export", []):
             full_name = os.path.join(section_path, e)
+            logger.info(full_name)
             exercise = load_json(full_name)
             if "exercise_id" not in exercise:
                 exercise["exercise_id"] = uuid.uuid4().hex
-                dump_json(full_name, exercise)
-
+                dump_json(full_name, exercise, exist_ok=True, override=True)