1. csv文件写入

​ 写入文件是一个非常简单的事情. 直接在pipeline中开启文件即可. 但这里要说明的是. 如果我们只在process_item中进行处理文件是不够优雅的. 总不能有一条数据就open一次吧

class CaipiaoFilePipeline:
    
    def process_item(self, item, spider):
        with open("caipiao.txt", mode="a", encoding='utf-8') as f:
            # 写入文件
            f.write(f"{item['qihao']}, {'_'.join(item['red_ball'])}, {'_'.join(item['blue_ball'])}\n")
        return item

​ 我们希望的是, 能不能打开一个文件, 然后就用这一个文件句柄来完成数据的保存. 答案是可以的. 我们可以在pipeline中创建两个方法, 一个是open_spider(), 另一个是close_spider(). 看名字也能明白其含义:

​ open_spider(), 在爬虫开始的时候执行一次
​ close_spider(), 在爬虫结束的时候执行一次

​ 有了这俩货, 我们就可以很简单的去处理这个问题

class CaipiaoFilePipeline:

    def open_spider(self, spider):
        self.f = open("caipiao.txt", mode="a", encoding='utf-8')

    def close_spider(self, spider):
        if self.f:
            self.f.close()

    def process_item(self, item, spider):
        # 写入文件
        self.f.write(f"{item['qihao']}, {'_'.join(item['red_ball'])}, {'_'.join(item['blue_ball'])}\n")
        return item

​ 在爬虫开始的时候打开一个文件, 在爬虫结束的时候关闭这个文件. 满分~

​ 对了, 别忘了设置settings

ITEM_PIPELINES = {
   'caipiao.pipelines.CaipiaoFilePipeline': 300,
}

2. mysql数据库写入

​ 有了上面的示例, 写入数据库其实也就很顺其自然了, 首先, 在open_spider中创建好数据库连接. 在close_spider中关闭链接. 在proccess_item中对数据进行保存工作.

先把mysql相关设置丢到settings里

# MYSQL配置信息
MYSQL_CONFIG = {
   "host": "localhost",
   "port": 3306,
   "user": "root",
   "password": "root",
   "database": "spider",
}

from caipiao.settings import MYSQL_CONFIG as mysql
import pymysql

class CaipiaoMySQLPipeline:

    def open_spider(self, spider):
        self.conn = pymysql.connect(host=mysql["host"], port=mysql["port"], user=mysql["user"], password=mysql["password"], database=mysql["database"])

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

    def process_item(self, item, spider):
        # 写入文件
        try:
            cursor = self.conn.cursor()
            sql = "insert into caipiao(qihao, red, blue) values(%s, %s, %s)"
            red = ",".join(item['red_ball'])
            blue = ",".join(item['blue_ball'])
            cursor.execute(sql, (item['qihao'], red, blue))
            self.conn.commit()
            spider.logger.info(f"保存数据{item}")
        except Exception as e:
            self.conn.rollback()
            spider.logger.error(f"保存数据库失败!", e, f"数据是: {item}")  # 记录错误日志
        return item

别忘了把pipeline设置一下

ITEM_PIPELINES = {
   'caipiao.pipelines.CaipiaoMySQLPipeline': 301,
}

3. mongodb数据库写入

​ mongodb数据库写入和mysql写入如出一辙…不废话直接上代码吧

MONGO_CONFIG = {
   "host": "localhost",
   "port": 27017,
   'has_user': True,
   'user': "python_admin",
   "password": "root",
   "db": "python"
}

from caipiao.settings import MONGO_CONFIG as mongo
import pymongo

class CaipiaoMongoDBPipeline:
    def open_spider(self, spider):
        client = pymongo.MongoClient(host=mongo['host'],
                                     port=mongo['port'])
        db = client[mongo['db']]
        if mongo['has_user']:
            db.authenticate(mongo['user'], mongo['password'])
        self.client = client
        self.collection = db['caipiao']

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

    def process_item(self, item, spider):
        self.collection.insert({"qihao": item['qihao'], 'red': item["red_ball"], 'blue': item['blue_ball']})
        return item

ITEM_PIPELINES = {
    # 三个管道可以共存~
   'caipiao.pipelines.CaipiaoFilePipeline': 300,
   'caipiao.pipelines.CaipiaoMySQLPipeline': 301,
   'caipiao.pipelines.CaipiaoMongoDBPipeline': 302,
}