python2.5版本中实现简单的json模块
2014-05-26 20:22
866 查看
项目开发中用到了一个工具,使用python2.5版本的,但是现在需要使用json模块,2.5版本中还没有集成json模块,python2.5又是集成在工具中的,不好升级,况且工具又是前人写的,都不熟悉,由于只用到了dumps这个函数,所有就自己从python2.7版本的源码中扒了这函数下来。
这里最主要的是两个类,json和encoder:
改编后如下:
(1)myJson
(2)myencoder:
这样就可以使用我们自己写的json类了:
{"a": "中文", "b": 2}
在扒这函数中用的笨方法是先把2.7版本的源码拷下来,然后电脑上再装python2.5版本的,然后根据编译器报的错一点一点修改,就搞定了。其他的函数我想应该也差不多这么做就能实现,但是因为没用到,就不花时间去扒了。
这里最主要的是两个类,json和encoder:
改编后如下:
(1)myJson
r"""JSON (JavaScript Object Notation) <http://json.org> is a subset of JavaScript syntax (ECMA-262 3rd edition) used as a lightweight data interchange format. :mod:`json` exposes an API familiar to users of the standard library :mod:`marshal` and :mod:`pickle` modules. It is the externally maintained version of the :mod:`json` library contained in Python 2.6, but maintains compatibility with Python 2.4 and Python 2.5 and (currently) has significant performance advantages, even without using the optional C extension for speedups. Encoding basic Python object hierarchies:: >>> import json >>> json.dumps(['foo', {'bar': ('baz', None, 1.0, 2)}]) '["foo", {"bar": ["baz", null, 1.0, 2]}]' >>> print json.dumps("\"foo\bar") "\"foo\bar" >>> print json.dumps(u'\u1234') "\u1234" >>> print json.dumps('\\') "\\" >>> print json.dumps({"c": 0, "b": 0, "a": 0}, sort_keys=True) {"a": 0, "b": 0, "c": 0} >>> from StringIO import StringIO >>> io = StringIO() >>> json.dump(['streaming API'], io) >>> io.getvalue() '["streaming API"]' Compact encoding:: >>> import json >>> json.dumps([1,2,3,{'4': 5, '6': 7}], sort_keys=True, separators=(',',':')) '[1,2,3,{"4":5,"6":7}]' Pretty printing:: >>> import json >>> print json.dumps({'4': 5, '6': 7}, sort_keys=True, ... indent=4, separators=(',', ': ')) { "4": 5, "6": 7 } Decoding JSON:: >>> import json >>> obj = [u'foo', {u'bar': [u'baz', None, 1.0, 2]}] >>> json.loads('["foo", {"bar":["baz", null, 1.0, 2]}]') == obj True >>> json.loads('"\\"foo\\bar"') == u'"foo\x08ar' True >>> from StringIO import StringIO >>> io = StringIO('["streaming API"]') >>> json.load(io)[0] == 'streaming API' True Specializing JSON object decoding:: >>> import json >>> def as_complex(dct): ... if '__complex__' in dct: ... return complex(dct['real'], dct['imag']) ... return dct ... >>> json.loads('{"__complex__": true, "real": 1, "imag": 2}', ... object_hook=as_complex) (1+2j) >>> from decimal import Decimal >>> json.loads('1.1', parse_float=Decimal) == Decimal('1.1') True Specializing JSON object encoding:: >>> import json >>> def encode_complex(obj): ... if isinstance(obj, complex): ... return [obj.real, obj.imag] ... raise TypeError(repr(o) + " is not JSON serializable") ... >>> json.dumps(2 + 1j, default=encode_complex) '[2.0, 1.0]' >>> json.JSONEncoder(default=encode_complex).encode(2 + 1j) '[2.0, 1.0]' >>> ''.join(json.JSONEncoder(default=encode_complex).iterencode(2 + 1j)) '[2.0, 1.0]' Using json.tool from the shell to validate and pretty-print:: $ echo '{"json":"obj"}' | python -m json.tool { "json": "obj" } $ echo '{ 1.2:3.4}' | python -m json.tool Expecting property name enclosed in double quotes: line 1 column 3 (char 2) """ __version__ = '2.0.9' __all__ = [ 'dump', 'dumps', 'load', 'loads', 'JSONDecoder', 'JSONEncoder', ] __author__ = 'Bob Ippolito <bob@redivi.com>' from myencoder import JSONEncoder _default_encoder = JSONEncoder( skipkeys=False, ensure_ascii=True, check_circular=True, allow_nan=True, indent=None, separators=None, encoding='utf-8', default=None, ) def dumps(obj, skipkeys=False, ensure_ascii=True, check_circular=True, allow_nan=True, cls=None, indent=None, separators=None, encoding='utf-8', default=None, sort_keys=False, **kw): """Serialize ``obj`` to a JSON formatted ``str``. If ``skipkeys`` is false then ``dict`` keys that are not basic types (``str``, ``unicode``, ``int``, ``long``, ``float``, ``bool``, ``None``) will be skipped instead of raising a ``TypeError``. If ``ensure_ascii`` is false, all non-ASCII characters are not escaped, and the return value may be a ``unicode`` instance. See ``dump`` for details. 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. Since the default item separator is ``', '``, the output might include trailing whitespace when ``indent`` is specified. You can use ``separators=(',', ': ')`` to avoid this. If ``separators`` is an ``(item_separator, dict_separator)`` tuple then it will be used instead of the default ``(', ', ': ')`` separators. ``(',', ':')`` is the most compact JSON representation. ``encoding`` is the character encoding for str instances, default is UTF-8. ``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 encoding == 'utf-8' 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, encoding=encoding, default=default, sort_keys=sort_keys, **kw).encode(obj)
(2)myencoder:
"""Implementation of JSONEncoder """ import re import sys try: from _json import encode_basestring_ascii as c_encode_basestring_ascii except ImportError: c_encode_basestring_ascii = None try: from _json import make_encoder as c_make_encoder except ImportError: c_make_encoder = None ESCAPE = re.compile(r'[\x00-\x1f\\"\b\f\n\r\t]') ESCAPE_ASCII = re.compile(r'([\\"]|[^\ -~])') HAS_UTF8 = re.compile(r'[\x80-\xff]') ESCAPE_DCT = { '\\': '\\\\', '"': '\\"', '\b': '\\b', '\f': '\\f', '\n': '\\n', '\r': '\\r', '\t': '\\t', } # for i in range(0x20): # ESCAPE_DCT.setdefault(chr(i), '\\u{0:04x}'.format(i)) # #ESCAPE_DCT.setdefault(chr(i), '\\u%04x' % (i,)) # INFINITY = float('inf') INFINITY = 123456789 FLOAT_REPR = repr def encode_basestring(s): """Return a JSON representation of a Python string """ def replace(match): return ESCAPE_DCT[match.group(0)] return '"' + ESCAPE.sub(replace, s) + '"' def py_encode_basestring_ascii(s): """Return an ASCII-only JSON representation of a Python string """ if isinstance(s, str) and HAS_UTF8.search(s) is not None: s = s.decode('utf-8') def replace(match): s = match.group(0) try: return ESCAPE_DCT[s] except KeyError: n = ord(s) if n < 0x10000: # return '\\u{0:04x}'.format(n) return '\\u%04x' % (n,) else: # surrogate pair n -= 0x10000 s1 = 0xd800 | ((n >> 10) & 0x3ff) s2 = 0xdc00 | (n & 0x3ff) # return '\\u{0:04x}\\u{1:04x}'.format(s1, s2) return '\\u%04x\\u%04x' % (s1, s2) return '"' + str(ESCAPE_ASCII.sub(replace, s)) + '"' encode_basestring_ascii = ( c_encode_basestring_ascii or py_encode_basestring_ascii) class JSONEncoder(object): """Extensible JSON <http://json.org> encoder for Python data structures. Supports the following objects and types by default: +-------------------+---------------+ | Python | JSON | +===================+===============+ | dict | object | +-------------------+---------------+ | list, tuple | array | +-------------------+---------------+ | str, unicode | string | +-------------------+---------------+ | int, long, float | number | +-------------------+---------------+ | True | true | +-------------------+---------------+ | False | false | +-------------------+---------------+ | None | null | +-------------------+---------------+ To extend this to recognize other objects, subclass and implement a ``.default()`` method with another method that returns a serializable object for ``o`` if possible, otherwise it should call the superclass implementation (to raise ``TypeError``). """ item_separator = ', ' key_separator = ': ' def __init__(self, skipkeys=False, ensure_ascii=True, check_circular=True, allow_nan=True, sort_keys=False, indent=None, separators=None, encoding='utf-8', default=None): """Constructor for JSONEncoder, with sensible defaults. If skipkeys is false, then it is a TypeError to attempt encoding of keys that are not str, int, long, float or None. If skipkeys is True, such items are simply skipped. If *ensure_ascii* is true (the default), all non-ASCII characters in the output are escaped with \uXXXX sequences, and the results are str instances consisting of ASCII characters only. If ensure_ascii is False, a result may be a unicode instance. This usually happens if the input contains unicode strings or the *encoding* parameter is used. If check_circular is true, then lists, dicts, and custom encoded objects will be checked for circular references during encoding to prevent an infinite recursion (which would cause an OverflowError). Otherwise, no such check takes place. If allow_nan is true, then NaN, Infinity, and -Infinity will be encoded as such. This behavior is not JSON specification compliant, but is consistent with most JavaScript based encoders and decoders. Otherwise, it will be a ValueError to encode such floats. If sort_keys is true, then the output of dictionaries will be sorted by key; this is useful for regression tests to ensure that JSON serializations can be compared on a day-to-day basis. 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. Since the default item separator is ', ', the output might include trailing whitespace when indent is specified. You can use separators=(',', ': ') to avoid this. If specified, separators should be a (item_separator, key_separator) tuple. The default is (', ', ': '). To get the most compact JSON representation you should specify (',', ':') to eliminate whitespace. If specified, default is a function that gets called for objects that can't otherwise be serialized. It should return a JSON encodable version of the object or raise a ``TypeError``. If encoding is not None, then all input strings will be transformed into unicode using that encoding prior to JSON-encoding. The default is UTF-8. """ self.skipkeys = skipkeys self.ensure_ascii = ensure_ascii self.check_circular = check_circular self.allow_nan = allow_nan self.sort_keys = sort_keys self.indent = indent if separators is not None: self.item_separator, self.key_separator = separators if default is not None: self.default = default self.encoding = encoding def default(self, o): """Implement this method in a subclass such that it returns a serializable object for ``o``, or calls the base implementation (to raise a ``TypeError``). For example, to support arbitrary iterators, you could implement default like this:: def default(self, o): try: iterable = iter(o) except TypeError: pass else: return list(iterable) # Let the base class default method raise the TypeError return JSONEncoder.default(self, o) """ raise TypeError(repr(o) + " is not JSON serializable") def encode(self, o): """Return a JSON string representation of a Python data structure. >>> JSONEncoder().encode({"foo": ["bar", "baz"]}) '{"foo": ["bar", "baz"]}' """ # This is for extremely simple cases and benchmarks. if isinstance(o, basestring): if isinstance(o, str): _encoding = self.encoding if (_encoding is not None and not (_encoding == 'utf-8')): o = o.decode(_encoding) if self.ensure_ascii: return encode_basestring_ascii(o) else: return encode_basestring(o) # This doesn't pass the iterator directly to ''.join() because the # exceptions aren't as detailed. The list call should be roughly # equivalent to the PySequence_Fast that ''.join() would do. chunks = self.iterencode(o, _one_shot=True) if not isinstance(chunks, (list, tuple)): chunks = list(chunks) return ''.join(chunks) def iterencode(self, o, _one_shot=False): """Encode the given object and yield each string representation as available. For example:: for chunk in JSONEncoder().iterencode(bigobject): mysocket.write(chunk) """ if self.check_circular: markers = {} else: markers = None if self.ensure_ascii: _encoder = encode_basestring_ascii else: _encoder = encode_basestring if self.encoding != 'utf-8': def _encoder(o, _orig_encoder=_encoder, _encoding=self.encoding): if isinstance(o, str): o = o.decode(_encoding) return _orig_encoder(o) def floatstr(o, allow_nan=self.allow_nan, _repr=FLOAT_REPR, _inf=INFINITY, _neginf=-INFINITY): # Check for specials. Note that this type of test is processor # and/or platform-specific, so do tests which don't depend on the # internals. if o != o: text = 'NaN' elif o == _inf: text = 'Infinity' elif o == _neginf: text = '-Infinity' else: return _repr(o) if not allow_nan: raise ValueError( "Out of range float values are not JSON compliant: " + repr(o)) return text if (_one_shot and c_make_encoder is not None and self.indent is None and not self.sort_keys): _iterencode = c_make_encoder( markers, self.default, _encoder, self.indent, self.key_separator, self.item_separator, self.sort_keys, self.skipkeys, self.allow_nan) else: _iterencode = _make_iterencode( markers, self.default, _encoder, self.indent, floatstr, self.key_separator, self.item_separator, self.sort_keys, self.skipkeys, _one_shot) return _iterencode(o, 0) def _make_iterencode(markers, _default, _encoder, _indent, _floatstr, _key_separator, _item_separator, _sort_keys, _skipkeys, _one_shot, ## HACK: hand-optimized bytecode; turn globals into locals ValueError=ValueError, basestring=basestring, dict=dict, float=float, id=id, int=int, isinstance=isinstance, list=list, long=long, str=str, tuple=tuple, ): def _iterencode_list(lst, _current_indent_level): if not lst: yield '[]' return if markers is not None: markerid = id(lst) if markerid in markers: raise ValueError("Circular reference detected") markers[markerid] = lst buf = '[' if _indent is not None: _current_indent_level += 1 newline_indent = '\n' + (' ' * (_indent * _current_indent_level)) separator = _item_separator + newline_indent buf += newline_indent else: newline_indent = None separator = _item_separator first = True for value in lst: if first: first = False else: buf = separator if isinstance(value, basestring): yield buf + _encoder(value) elif value is None: yield buf + 'null' elif value is True: yield buf + 'true' elif value is False: yield buf + 'false' elif isinstance(value, (int, long)): yield buf + str(value) elif isinstance(value, float): yield buf + _floatstr(value) else: yield buf if isinstance(value, (list, tuple)): chunks = _iterencode_list(value, _current_indent_level) elif isinstance(value, dict): chunks = _iterencode_dict(value, _current_indent_level) else: chunks = _iterencode(value, _current_indent_level) for chunk in chunks: yield chunk if newline_indent is not None: _current_indent_level -= 1 yield '\n' + (' ' * (_indent * _current_indent_level)) yield ']' if markers is not None: del markers[markerid] def _iterencode_dict(dct, _current_indent_level): if not dct: yield '{}' return if markers is not None: markerid = id(dct) if markerid in markers: raise ValueError("Circular reference detected") markers[markerid] = dct yield '{' if _indent is not None: _current_indent_level += 1 newline_indent = '\n' + (' ' * (_indent * _current_indent_level)) item_separator = _item_separator + newline_indent yield newline_indent else: newline_indent = None item_separator = _item_separator first = True if _sort_keys: items = sorted(dct.items(), key=lambda kv: kv[0]) else: items = dct.iteritems() for key, value in items: if isinstance(key, basestring): pass # JavaScript is weakly typed for these, so it makes sense to # also allow them. Many encoders seem to do something like this. elif isinstance(key, float): key = _floatstr(key) elif key is True: key = 'true' elif key is False: key = 'false' elif key is None: key = 'null' elif isinstance(key, (int, long)): key = str(key) elif _skipkeys: continue else: raise TypeError("key " + repr(key) + " is not a string") if first: first = False else: yield item_separator yield _encoder(key) yield _key_separator if isinstance(value, basestring): yield _encoder(value) elif value is None: yield 'null' elif value is True: yield 'true' elif value is False: yield 'false' elif isinstance(value, (int, long)): yield str(value) elif isinstance(value, float): yield _floatstr(value) else: if isinstance(value, (list, tuple)): chunks = _iterencode_list(value, _current_indent_level) elif isinstance(value, dict): chunks = _iterencode_dict(value, _current_indent_level) else: chunks = _iterencode(value, _current_indent_level) for chunk in chunks: yield chunk if newline_indent is not None: _current_indent_level -= 1 yield '\n' + (' ' * (_indent * _current_indent_level)) yield '}' if markers is not None: del markers[markerid] def _iterencode(o, _current_indent_level): if isinstance(o, basestring): yield _encoder(o) elif o is None: yield 'null' elif o is True: yield 'true' elif o is False: yield 'false' elif isinstance(o, (int, long)): yield str(o) elif isinstance(o, float): yield _floatstr(o) elif isinstance(o, (list, tuple)): for chunk in _iterencode_list(o, _current_indent_level): yield chunk elif isinstance(o, dict): for chunk in _iterencode_dict(o, _current_indent_level): yield chunk else: if markers is not None: markerid = id(o) if markerid in markers: raise ValueError("Circular reference detected") markers[markerid] = o o = _default(o) for chunk in _iterencode(o, _current_indent_level): yield chunk if markers is not None: del markers[markerid] return _iterencode
这样就可以使用我们自己写的json类了:
# -*- coding: utf-8 -*- import myJson dicts = {"a":"中文","b":2} jsonStr = myJson.dumps(dicts,ensure_ascii=False) print jsonStr输出结果:
{"a": "中文", "b": 2}
在扒这函数中用的笨方法是先把2.7版本的源码拷下来,然后电脑上再装python2.5版本的,然后根据编译器报的错一点一点修改,就搞定了。其他的函数我想应该也差不多这么做就能实现,但是因为没用到,就不花时间去扒了。
相关文章推荐
- python —— 使用logging模块简单实现日志系统
- python-json模块简单使用
- Python中-JSON模块的简单介绍
- 用python的wxpython模块实现一个简单的与用户可以交互计算器
- python读写json文件的简单实现
- python json模块简单运用
- Python读写json文件的简单实现
- python 利用sklearn自带的模块 快速简单实现文章的 tfidf向量空间的表示
- python中json格式数据输出的简单实现方法
- Python处理json字符串转化为字典的简单实现
- Python实现简单生成验证码功能【基于random模块】
- python 多进程通信模块的简单实现
- Python入门简单的静态网页爬虫2.0 (实现各模块的具体方法)
- 【python学习笔记】flask实现简单的接收json返回json的接口
- Python学习—paramiko模块实现简单的ssh与sftp
- python序列化pickle模块和json模块简单学习
- python-简单的用户与密码登录模块实现
- Python处理json字符串转化为字典的简单实现
- python的2.5与2.7版本中ftp模块的一个小区别
- 简单介绍Python中的JSON模块