我想从 JSON 数据文件中提取用户名。
[{"username": "Cobra", "user_id": 146231486, "event_type": 2,
"title": null, "class_id": 4211, "war_state" : null,
"superpower_expire_date": 1441178060.0, "role": 3, "event_state": 2,
"avatar_id": 4211, "avatar_type" : 2, "recent_gifts": []},
{"username": "Divineshadow", "user_id": 1622533959, "event_type": 2,
"title" : null, "class_id": 1887, "war_state": null,
"superpower_expire_date": null, "role": 2, "event_state" : 2,
"avatar_id": 1887, "avatar_type": 2, "recent_gifts": []}, {"username":
"-TheLastTrojan_", "user_id" : 1387569472, "event_type": 2, "title":
null, "class_id": 1887, "war_state": null, "superpower_expire_date" :
1440106625.0, "role": 1, "event_state": 3, "avatar_id": 1887,
"avatar_type": 2, "recent_gifts": …