scrapy相关 通过设置 FEED_EXPORT_ENCODING 解决 unicode 中文写入json文件出现`\uXXXX`

0.问题现象

爬取 item：

2017-10-16 18:17:33 [scrapy.core.scraper] DEBUG: Scraped from <200 https://www.huxiu.com/v2_action/article_list>
{'author': u'\u5546\u4e1a\u8bc4\u8bba\u7cbe\u9009\xa9',
 'cmt': 5,
 'fav': 194,
 'time': u'4\u5929\u524d',
 'title': u'\u96f7\u519b\u8c08\u5c0f\u7c73\u201c\u65b0\u96f6\u552e\u201d\uff1a\u50cfZara\u4e00\u6837\u5f00\u5e97\uff0c\u8981\u505a\u5f97\u6bd4Costco\u66f4\u597d',
 'url': u'/article/217755.html'}

写入jsonline jl 文件

{"title": "\u8fd9\u4e00\u5468\uff1a\u8d2b\u7a77\u66b4\u51fb", "url": "/article/217997.html", "author": "\u864e\u55c5", "fav": 8, "time": "2\u5929\u524d", "cmt": 5}
{"title": "\u502a\u840d\u8001\u516c\u7684\u65b0\u620f\u6251\u8857\u4e86\uff0c\u9ec4\u6e24\u6301\u80a1\u7684\u516c\u53f8\u8981\u8d54\u60e8\u4e86", "url": "/article/217977.html", "author": "\u5a31\u4e50\u8d44\u672c\u8bba", "fav": 5, "time": "2\u5929\u524d", "cmt": 3}

item 被转 str，默认 ensure_ascii = True，则非 ASCII 字符被转化为 `\uXXXX`，每一个 ‘{xxx}’ 单位被写入文件

目标：注意最后用 chrome 或 notepad++ 打开确认，firefox 打开 jl 可能出现中文乱码，需要手动指定编码。

{"title": "这一周：贫穷暴击", "url": "/article/217997.html", "author": "虎嗅", "fav": 8, "time": "2天前", "cmt": 5}
{"title": "倪萍老公的新戏扑街了，黄渤持股的公司要赔惨了", "url": "/article/217977.html", "author": "娱乐资本论", "fav": 5, "time": "2天前", "cmt": 3}

1.参考资料

scrapy抓取到中文,保存到json文件为unicode,如何解决.

import json
import codecs

class JsonWithEncodingPipeline(object):

    def __init__(self):
        self.file = codecs.open('scraped_data_utf8.json', 'w', encoding='utf-8')

    def process_item(self, item, spider):^M
        line = json.dumps(dict(item), ensure_ascii=False) + "\n"
        self.file.write(line)
        return item

    def close_spider(self, spider):
        self.file.close()

scrapy中输出中文保存中文

Scrapy爬虫框架抓取中文结果为Unicode编码，如何转换UTF-8编码

lidashuang / imax-spider

以上资料实际上就是官方文档举的 pipeline 例子，另外指定  ensure_ascii=False

Write items to a JSON file

The following pipeline stores all scraped items (from all spiders) into a single items.jl file, containing one item per line serialized in JSON format:

import json

class JsonWriterPipeline(object):

    def open_spider(self, spider):
        self.file = open('items.jl', 'w')

    def close_spider(self, spider):
        self.file.close()

    def process_item(self, item, spider):
        line = json.dumps(dict(item)) + "\n"  #另外指定  ensure_ascii=False
        self.file.write(line)
        return item

Note

The purpose of JsonWriterPipeline is just to introduce how to write item pipelines. If you really want to store all scraped items into a JSON file you should use the Feed exports.

2.更好的解决办法：

scrapy 使用item export输出中文到json文件，内容为unicode码，如何输出为中文？

http://stackoverflow.com/questions/18337407/saving-utf-8-texts-in-json-dumps-as-utf8-not-as-u-escape-sequence 里面有提到，将 JSONEncoder 的 ensure_ascii 参数设为 False 即可。

而 scrapy 的 item export 文档里有提到

The additional constructor arguments are passed to the
BaseItemExporter constructor, and the leftover arguments to the
JSONEncoder constructor, so you can use any JSONEncoder constructor
argument to customize this exporter.

因此就在调用 scrapy.contrib.exporter.JsonItemExporter 的时候额外指定 ensure_ascii=False 就可以啦。

3.根据上述解答，结合官网和源代码，直接解决办法：

1.可以通过修改 project settings.py 补充 FEED_EXPORT_ENCODING = 'utf-8'

2.或在cmd中传入 G:\pydata\pycode\scrapy\huxiu_com>scrapy crawl -o new.jl -s FEED_EXPORT_ENCODING='utf-8' huxiu

https://doc.scrapy.org/en/latest/topics/feed-exports.html#feed-export-encoding

FEED_EXPORT_ENCODING

Default: None

The encoding to be used for the feed.

If unset or set to None (default) it uses UTF-8 for everything except JSON output, which uses safe numeric encoding (\uXXXX sequences) for historic reasons.

Use utf-8 if you want UTF-8 for JSON too.

In [615]: json.dump?
Signature: json.dump(obj, fp, 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)
Docstring:
Serialize ``obj`` as a JSON formatted stream to ``fp`` (a
``.write()``-supporting file-like object).

If ``ensure_ascii`` is true (the default), all non-ASCII characters in the
output are escaped with ``\uXXXX`` sequences, and the result is a ``str``
instance consisting of ASCII characters only. If ``ensure_ascii`` is
``False``, some chunks written to ``fp`` may be ``unicode`` instances.
This usually happens because the input contains unicode strings or the
``encoding`` parameter is used. Unless ``fp.write()`` explicitly
understands ``unicode`` (as in ``codecs.getwriter``) this is likely to
cause an error.

C:\Program Files\Anaconda2\Lib\site-packages\scrapy\exporters.py

class JsonLinesItemExporter(BaseItemExporter):

    def __init__(self, file, **kwargs):
        kwargs.setdefault('ensure_ascii', not self.encoding)

class JsonItemExporter(BaseItemExporter):
    def __init__(self, file, **kwargs):
        kwargs.setdefault('ensure_ascii', not self.encoding)

class XmlItemExporter(BaseItemExporter):

    def __init__(self, file, **kwargs):
        if not self.encoding:
            self.encoding = 'utf-8'