我的想法是输入用户名，若用户名不存在则创建一个json文件来记录此用户名，若存在则输出welcome

import json
    username = input("input your username\n")
    file_name = 'username.json'
try:
    with open(file_name):
        name = json.load(file_name)
except FileNotFoundError:
    with open(file_name, 'w'):

        json.dump(username, file_name) 

        print("back in any time")
else:
    print("welcome back " + name)

错误反馈的是

File "program.py", line 6, in <module>
name = json.load(file_name)
File "/usr/lib/python3.6/json/__init__.py", line 296, in load
return loads(fp.read(),
AttributeError: 'str' object has no attribute 'read'

如何解决