如何获取字符串中某个具体的数值--通过json.load转化成字典形式获取

r=requests.get('http://httpbin.org/get').text
print(r)
# print(type(r))
# 如果要获取User-Agent的详细数值，需要做JSON转换
r_json=json.loads(r)
print(r_json)
print(type(r_json))
print(r_json['headers']['User-Agent'])

输出结果为：

 "C:\Program Files\Anaconda3\python.exe" "D:/pycharm/test2/python gaoji.py"
 {
   "args": {},
   "headers": {
     "Accept": "*/*",
     "Accept-Encoding": "gzip, deflate",
     "Connection": "close",
     "Host": "httpbin.org",
     "User-Agent": "python-requests/2.11.1"
   },
   "origin": "114.252.235.73",
   "url": "http://httpbin.org/get"
 }

 {'url': 'http://httpbin.org/get', 'headers': {'Connection': 'close', 'Accept': '*/*', 'Accept-Encoding': 'gzip, deflate', 'Host': 'httpbin.org', 'User-Agent': 'python-requests/2.11.1'}, 'origin': '114.252.235.73', 'args': {}}
 <class 'dict'>
 python-requests/2.11.1