如何在更改文件名时*不*更改文件扩展名？

import os

def change_filename_without_extension(file_path, new_filename):
    # 获取文件的目录和扩展名
    directory, filename_with_extension = os.path.split(file_path)
    name, extension = os.path.splitext(filename_with_extension)
    
    # 构建新的文件名
    new_filename_with_extension = new_filename + extension
    
    # 构建新的完整文件路径
    new_file_path = os.path.join(directory, new_filename_with_extension)
    
    # 重命名文件
    os.rename(file_path, new_file_path)
    return new_file_path

# 示例用法
file_path = 'path/to/your/file.txt'
new_filename = 'new_file_name'
new_file_path = change_filename_without_extension(file_path, new_filename)
print(f'File has been renamed to: {new_file_path}')