import os
#文件索引
def scan_files(directory,prefix=None,postfix=None):
    files_list=[]
    for root, sub_dirs, files in os.walk(directory):
        for special_file in files:
            if postfix:
                if special_file.endswith(postfix):
                    files_list.append(os.path.join(root,special_file))
            elif prefix:
                if special_file.startswith(prefix):
                    files_list.append(os.path.join(root,special_file))
            else:
                files_list.append(os.path.join(root,special_file))
                          
    return files_list