Python json格式化打印实现过程解析

import json
import requests

def test_json():
  r=requests.get('https://home.testing-studio.com/categories.json')
  print(r.json())
  print(json.dumps(r.json(), indent=2,ensure_ascii=False)) # r.json()是json对象，indent表示缩进，ensure_ascii设置编码
格式化打印前：

def dumps(obj, *, skipkeys=False, ensure_ascii=True, check_circular=True,
    allow_nan=True, cls=None, indent=None, separators=None,
    default=None, sort_keys=False, **kw):
  """Serialize ``obj`` to a JSON formatted ``str``.

  If ``skipkeys`` is true then ``dict`` keys that are not basic types
  (``str``, ``int``, ``float``, ``bool``, ``None``) will be skipped
  instead of raising a ``TypeError``.

  If ``ensure_ascii`` is false, then the return value can contain non-ASCII
  characters if they appear in strings contained in ``obj``. Otherwise, all
  such characters are escaped in JSON strings.

  If ``check_circular`` is false, then the circular reference check
  for container types will be skipped and a circular reference will
  result in an ``OverflowError`` (or worse).

  If ``allow_nan`` is false, then it will be a ``ValueError`` to
  serialize out of range ``float`` values (``nan``, ``inf``, ``-inf``) in
  strict compliance of the JSON specification, instead of using the
  JavaScript equivalents (``NaN``, ``Infinity``, ``-Infinity``).

  If ``indent`` is a non-negative integer, then JSON array elements and
  object members will be pretty-printed with that indent level. An indent
  level of 0 will only insert newlines. ``None`` is the most compact
  representation.

  If specified, ``separators`` should be an ``(item_separator, key_separator)``
  tuple. The default is ``(', ', ': ')`` if *indent* is ``None`` and
  ``(',', ': ')`` otherwise. To get the most compact JSON representation,
  you should specify ``(',', ':')`` to eliminate whitespace.

  ``default(obj)`` is a function that should return a serializable version
  of obj or raise TypeError. The default simply raises TypeError.

  If *sort_keys* is true (default: ``False``), then the output of
  dictionaries will be sorted by key.

  To use a custom ``JSONEncoder`` subclass (e.g. one that overrides the
  ``.default()`` method to serialize additional types), specify it with
  the ``cls`` kwarg; otherwise ``JSONEncoder`` is used.

  """
  # cached encoder
  if (not skipkeys and ensure_ascii and
    check_circular and allow_nan and
    cls is None and indent is None and separators is None and
    default is None and not sort_keys and not kw):
    return _default_encoder.encode(obj)
  if cls is None:
    cls = JSONEncoder
  return cls(
    skipkeys=skipkeys, ensure_ascii=ensure_ascii,
    check_circular=check_circular, allow_nan=allow_nan, indent=indent,
    separators=separators, default=default, sort_keys=sort_keys,
    **kw).encode(obj)