scrapy框架ItemPipeline的使用

ITEM_PIPELINES = {
    'myproject.pipelines.PricePipeline': 300,
    'myproject.pipelines.JsonWriterPipeline': 800,
}

import json
class JsonWriterPipeline(object):
    def __init__(self):
        self.file = open('items.json', 'wb')
    def process_item(self, item, spider):
        line = json.dumps(dict(item),ensure_ascii=False) + "\n"
        self.file.write(line)
        return item

import json
import codecs
class JsonWriterPipeline(object):
    def __init__(self):
        self.file = codecs.open('items.json', 'w', encoding='utf-8')
    def process_item(self, item, spider):
        line = json.dumps(dict(item), ensure_ascii=False) + "\n"
        self.file.write(line)
        return item
    def spider_closed(self, spider):
        self.file.close()

item = RecruitItem()
item['name']=name.encode('utf-8')
item['detailLink']=detailLink.encode('utf-8')
item['catalog']=catalog.encode('utf-8')
item['recruitNumber']=recruitNumber.encode('utf-8')
item['workLocation']=workLocation.encode('utf-8')
item['publishTime']=publishTime.encode('utf-8')

import pymongo
class MongoPipeline(object):
    collection_name = 'scrapy_items'
    def __init__(self, mongo_uri, mongo_db):
        self.mongo_uri = mongo_uri
        self.mongo_db = mongo_db
    @classmethod
    def from_crawler(cls, crawler):
        return cls(
            mongo_uri=crawler.settings.get('MONGO_URI'),
            mongo_db=crawler.settings.get('MONGO_DATABASE', 'items')
        )
    def open_spider(self, spider):
        self.client = pymongo.MongoClient(self.mongo_uri)
        self.db = self.client[self.mongo_db]
    def close_spider(self, spider):
        self.client.close()
    def process_item(self, item, spider):
        self.db[self.collection_name].insert(dict(item))
        return item