在使用google.protobuf 的json_format.MessageToJson时，出现了中文字段变成了ascii编码了，如下:

"WeaponNickName": "\u6c99\u9e70",

因此查阅python google.protobuf中json_format.MessageToJson的引用关系如下：

在json_format.py中有如下代码：

def MessageToJson(
    message,
    including_default_value_fields=False,
    preserving_proto_field_name=False,
    indent=2,
    sort_keys=False,
    use_integers_for_enums=False,
    descriptor_pool=None,
    float_precision=None):
  """Converts protobuf message to JSON format.

  Args:
    message: The protocol buffers message instance to serialize.
    including_default_value_fields: If True, singular primitive fields,
        repeated fields, and map fields will always be serialized.  If
        False, only serialize non-empty fields.  Singular message fields
        and oneof fields are not affected by this option.
    preserving_proto_field_name: If True, use the original proto field
        names as defined in the .proto file. If False, convert the field
        names to lowerCamelCase.
    indent: The JSON object will be pretty-printed with this indent level.
        An indent level of 0 or negative will only insert newlines.
    sort_keys: If True, then the output will be sorted by field names.
    use_integers_for_enums: If true, print integers instead of enum names.
    descriptor_pool: A Descriptor Pool for resolving types. If None use the
        default.
    float_precision: If set, use this to specify float field valid digits.

  Returns:
    A string containing the JSON formatted protocol buffer message.
  """
  printer = _Printer(
      including_default_value_fields,
      preserving_proto_field_name,
      use_integers_for_enums,
      descriptor_pool,
      float_precision=float_precision)
  return printer.ToJsonString(message, indent, sort_keys)

float_precision：这个字段就是设置浮点精度的，我可以设置为3，保留3位小数。

 

接着往下看printer.ToJsonString：

  def ToJsonString(self, message, indent, sort_keys):
    js = self._MessageToJsonObject(message)
    return json.dumps(js, indent=indent, sort_keys=sort_keys)

发现最终调用的是大家熟悉的json.dumps函数，进入看（截取源码片段），

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.

原来这里有个ensure_ascii选项，默认是True，但是上面ToJsonString函数没有传参，因此会变成asciil编码了，因此我们可以修改源码，把ensure_ascii 设置为false。

改变就是逆向的过程，具体操作如下：

在ToJsonString中，增加ensure_ascii参数

  def ToJsonString(self, message, indent, sort_keys, ensure_ascii):
    js = self._MessageToJsonObject(message)
    return json.dumps(js, indent=indent, sort_keys=sort_keys, ensure_ascii=ensure_ascii)

在MessageToJson中加入参数：

def MessageToJson(
    message,
    including_default_value_fields=False,
    preserving_proto_field_name=False,
    indent=2,
    sort_keys=False,
    use_integers_for_enums=False,
    descriptor_pool=None,
    float_precision=None,
    ensure_ascii = True):
  """Converts protobuf message to JSON format.

  Args:
    message: The protocol buffers message instance to serialize.
    including_default_value_fields: If True, singular primitive fields,
        repeated fields, and map fields will always be serialized.  If
        False, only serialize non-empty fields.  Singular message fields
        and oneof fields are not affected by this option.
    preserving_proto_field_name: If True, use the original proto field
        names as defined in the .proto file. If False, convert the field
        names to lowerCamelCase.
    indent: The JSON object will be pretty-printed with this indent level.
        An indent level of 0 or negative will only insert newlines.
    sort_keys: If True, then the output will be sorted by field names.
    use_integers_for_enums: If true, print integers instead of enum names.
    descriptor_pool: A Descriptor Pool for resolving types. If None use the
        default.
    float_precision: If set, use this to specify float field valid digits.

  Returns:
    A string containing the JSON formatted protocol buffer message.
  """
  printer = _Printer(
      including_default_value_fields,
      preserving_proto_field_name,
      use_integers_for_enums,
      descriptor_pool,
      float_precision=float_precision)
  return printer.ToJsonString(message, indent, sort_keys, ensure_ascii)

在调用的地方

_json_result = json_format.MessageToJson(_data, True, True, 2, True, False, None, 3)