1.搭建虚拟python3环境（Virtualenvwrapper）

参考http://www.cnblogs.com/it-tsz/p/pyhton.html

2.安装scrapy

前提先安装好pip,setuptools，然后安装以下模块

pip install lxml

pip install twisted

pip install pyopenssl

windows下需要安装pywin32(pip install pywin32)

最后安装scrapy

pip install scrapy

3.通过scrapy生成scrapy spider 工程模版

scrapy startproject <project_name> [project_dir]

如：

scrapy startproject budejie

4.生成spider模块

scrapy genspider [options] <name> <domain>

如：

cd budejie

scrapy genspider getbudejievideo budejie.com

5.修改spider模块（getbudejievideo.py）

# -*- coding: utf-8 -*-
import scrapy
import os
import urllib
from lxml import etree

# urlretrieve()的回调函数，显示当前的下载进度
# a为已经下载的数据块
# b为数据块大小
# c为远程文件的大小

def jindu(a, b, c):
    if not a:
        print("连接打开")
    if c < 0:
        print("要下载的文件大小为0")
    else:

        per = 100 * a * b / c

        if per > 100:
            per = 100
        print("\r当前下载进度为：" + '%.2f%%' % per, end='')
    if per == 100:
        return True

''' def __init__(self):
        self.headers = {
        # 'Content-Type': 'application/x-www-form-urlencoded; charset=UTF-8',
        # 'Accept-Encoding': 'gzip, deflate',
        'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/50.0.2661.102 Safari/537.36'
        }
   '''

class GetbudejievideoSpider(scrapy.Spider):
    name = 'getbudejievideo'
    allowed_domains = ['budejie.com']
    start_urls = ['http://budejie.com/video']   

    cur_page = 1

    def parse(self, response):
        print('*' * 100)      

        # 创建video文件保持目录
        path = os.path.join(os.path.abspath(os.path.curdir), 'videos')
        if not os.path.exists(path):
            os.mkdir(path)
        # 获取当前页所有video 的url

        try:
            data = etree.HTML(response.text)
            video_urls = data.xpath('//div[@class="j-video-c"]/div[@data-mp4]')

            # <a href="2" class="pagenxt">下一页</a>
            nextpage = data.xpath('//a[@class="pagenxt"]')
            if nextpage:
                nextpage = nextpage[0].get('href')

        except Exception:
            print('lxml parse failed------------------------------')
            return
        if not video_urls:
            return
        # 下载当前页下所有video url对应的视频文件
        for v in video_urls:
            # if v:
            video_url = v.get('data-mp4')
            print('下载：{}'.format(video_url))
            p = os.path.join(path, v.get('data-mp4').split('/')[-1])

            print(p)

            if not os.path.exists(p):
                try:
                    urllib.request.urlretrieve(video_url, p, jindu)
                except Exception:
                    print("\n下载文件：{}失败".format(video_url))

        # 检测是否有下一页
        if nextpage:
            if nextpage == '1':
                return
            nextpage_url = self.start_urls【0】 + '/' + nextpage

            self.cur_page += 1
            print('\n下载第{}页视频数据:{}'.format(self.cur_page, nextpage_url))
            #通过生成器对新生成的url继续回调parse
            yield scrapy.Request(nextpage_url, callback=self.parse)

        else:
            return
4.修改配置文件settings.py以下参数选项
。。。
#以下为模拟浏览器验证

# Crawl responsibly by identifying yourself (and your website) on the user-agent
# USER_AGENT = 'budejie (+http://www.budejie.com)'
USER_AGENT = 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/65.0.3325.181 Safari/537.36'

# Obey robots.txt rules 跳过robots协议验证
ROBOTSTXT_OBEY = False
。。。
5.通过scrapy开启爬虫数据采集
scrapy crawl getbudejievideo
6.测试成功。
通过该案例，进一步学习了scrapy,xpath等相关知识，实践过程中提高了分析问题和解决问题的能力，继续加油！

不使用外部xpath库源代码修改spider模块（getbudejievideo.py）修改如下：

# -*- coding: utf-8 -*-
import scrapy
import os
import urllib
import re

# urlretrieve()的回调函数，显示当前的下载进度
# a为已经下载的数据块
# b为数据块大小
# c为远程文件的大小

def jindu(a, b, c):
    if not a:
        print("连接打开")
    if c < 0:
        print("要下载的文件大小为0")
    else:
        # global myper
        per = 100 * a * b / c

        if per > 100:
            per = 100
        print("\r当前下载进度为：" + '%.2f%%' % per, end='')
    if per == 100:
        return True

class GetbudejievideoSpider(scrapy.Spider):
    name = 'getbudejievideo'
    allowed_domains = ['www.budejie.com']
    start_urls = ['http://www.budejie.com/video']

    cur_page = 1

    def parse(self, response):
        print('下载url:{}'.format(response.url))
        # 创建video文件保持目录
        path = os.path.join(os.path.abspath(os.path.curdir), 'videos')
        if not os.path.exists(path):
            os.mkdir(path)
        # 获取当前页所有video 的url
        print('-' * 100)
        try:
            # data = etree.HTML(response.text)
            video_urls = response.xpath('//div[@class="j-video-c"]/div[@data-mp4]').extract()
            v_urls=[]
            for i in video_urls:
                v= re.findall(r'data-mp4="(.*?)"', i,re.M)
                if v:
                    v_urls.append(v[0])
            # <a href="2" class="pagenxt">下一页</a>
            nextpage = response.xpath('//a[@class="pagenxt"]').extract()
            if nextpage:
                nextpage = re.findall(r'href="(.*?)"', nextpage[0])

        except Exception:
            print('lxml parse failed:')
            return
        if not v_urls:
            return
        # 下载当前页下所有video url对应的视频文件
        for v in v_urls:
            # video_url = v.get('data-mp4')
            print('下载：{}'.format(v))
            p = os.path.join(path, v.split('/')[-1])

            print(p)

            if not os.path.exists(p):
                try:
                    urllib.request.urlretrieve(v, p, jindu)
                except Exception:
                    print("\n下载文件：{}失败".format(v))

        # 检测是否有下一页
        if nextpage:
            if nextpage[0] == '1':
                return

            nextpage_url = self.start_urls[0] + '/' + nextpage[0]
            print(nextpage_url)

            self.cur_page += 1
            print('\n下载第{}页视频数据:{}'.format(self.cur_page, nextpage_url))
            # 通过生成器对新生成的url继续回调parse
            yield scrapy.Request(nextpage_url, callback=self.parse)
        else:
            return

附属调试模块：（debug.py）

from scrapy import cmdline

if __name__ == '__main__':
    cmdline.execute('scrapy crawl getbudejievideo'.split(' '))

from scrapy import cmdline

if __name__ == '__main__':
    cmdline.execute('scrapy crawl getbudejievideo'.split(' '))