pyspider爬虫学习-教程3-Render-with-PhantomJS.md
博客专区 > sijinge 的博客 > 博客详情
pyspider爬虫学习-教程3-Render-with-PhantomJS.md
sijinge 发表于3个月前
pyspider爬虫学习-教程3-Render-with-PhantomJS.md
  • 发表于 3个月前
  • 阅读 13
  • 收藏 0
  • 点赞 0
  • 评论 0

腾讯云 新注册用户 域名抢购1元起>>>   

摘要: pyspider爬虫学习-教程3 Render with PhantomJS
Level 3: Render with PhantomJS
==============================
#有时web页面太复杂,无法找到API请求。现在是时候迎接[PhantomJS]的力量了
Sometimes web page is too complex to find out the API request. It's time to meet the power of [PhantomJS].
#使用PhantomJS,你应该已经安装PhantomJS(http://phantomjs.org/download.html)。如果你运行的是'all'模式的pyspider,如果在“路径”中有excutable,则会启用PhantomJS。
To use PhantomJS, you should have PhantomJS [installed](http://phantomjs.org/download.html). If you are running pyspider with `all` mode, PhantomJS is enabled if excutable in the `PATH`.
#确保phantomjs正在运行
Make sure phantomjs is working by running
```
$ pyspider phantomjs
```
如果输出是Web服务器运行在25555端口上,则继续教程的其余部分
Continue with the rest of the tutorial if the output is
```
Web server running on port 25555
```
#使用PhantomJS
Use PhantomJS
-------------
#
#当pyspider与PhantomJS连接在一起时,您可以通过向'self.crawl'添加一个参数“fetch_type='js'”来启用这个特性。我们使用PhantomJS获取频道列表[http://www.twitch.tv/directory/game/Dota%202](http://www.twitch.tv/directory/game/Dota%202)中使用AJAX加载我们讨论[Level 2](tutorial/AJAX-and-more-HTTP#ajax):
When pyspider with PhantomJS connected, you can enable this feature by adding a parameter `fetch_type='js'` to `self.crawl`. We use PhantomJS to scrape channel list of  [http://www.twitch.tv/directory/game/Dota%202](http://www.twitch.tv/directory/game/Dota%202) which is loaded with AJAX we discussed in [Level 2](tutorial/AJAX-and-more-HTTP#ajax):

```
class Handler(BaseHandler):
    def on_start(self):
        self.crawl('http://www.twitch.tv/directory/game/Dota%202',
                   fetch_type='js', callback=self.index_page)
             
    def index_page(self, response):
        return {
            "url": response.url,
            "channels": [{
                "title": x('.title').text(),
                "viewers": x('.info').contents()[2],
                "name": x('.info a').text(),
            } for x in response.doc('.stream.item').items()]
        }
```
#我使用了一些API来处理流列表。你可以找到完整的API参考[PyQuery完整的API](https://pythonhosted.org/pyquery/api.html)
> I used some API to handle the list of streams. You can find complete API reference from [PyQuery complete API](https://pythonhosted.org/pyquery/api.html)

#在页面运行JavaScript脚本
Running JavaScript on Page
--------------------------
#在这一部分中我们将尝试截取图像[http://www.pinterest.com/categories/popular/](http://www.pinterest.com/categories/popular/)。在开始时,只有25个图像显示,当你滚动到页面底部时,会加载更多的图片。
We will try to scrape images from [http://www.pinterest.com/categories/popular/](http://www.pinterest.com/categories/popular/) in this section. Only 25 images is shown at the beginning, more images would be loaded when you scroll to the bottom of the page.
#我们可以使用[`js_script` parameter](/apis/self.crawl/#enable-javascript-fetcher-need-support-by-fetcher)来对图像进行尽可能多的抓取,设置一些JavaScript代码包装的函数来模拟滚动操作
To scrape images as many as posible we can use a [`js_script` parameter](/apis/self.crawl/#enable-javascript-fetcher-need-support-by-fetcher) to set some function wrapped JavaScript codes to simulate the scroll action: 

```
class Handler(BaseHandler):
    def on_start(self):
        self.crawl('http://www.pinterest.com/categories/popular/',
                   fetch_type='js', js_script="""
                   function() {
                       window.scrollTo(0,document.body.scrollHeight);
                   }
                   """, callback=self.index_page)

    def index_page(self, response):
        return {
            "url": response.url,
            "images": [{
                "title": x('.richPinGridTitle').text(),
                "img": x('.pinImg').attr('src'),
                "author": x('.creditName').text(),
            } for x in response.doc('.item').items() if x('.pinImg')]
        }
```
# 脚本在加载页面后执行(可以通过[`js_run_at` parameter](/apis/self.crawl/#enable-javascript-fetcher-need-support-by-fetcher)进行更改)。
> * Script would been executed after page loaded(can been changed via [`js_run_at` parameter](/apis/self.crawl/#enable-javascript-fetcher-need-support-by-fetcher))
#我们滚动页面加载后,你可以滚动多次在[`setTimeout`]时间内(https://developer.mozilla.org/en-US/docs/Web/API/WindowTimers.setTimeout)。PhantomJS将在超时之前获取尽可能多的项目。
> * We scroll once after page loaded, you can scroll multiple times using [`setTimeout`](https://developer.mozilla.org/en-US/docs/Web/API/WindowTimers.setTimeout). PhantomJS will fetch as many items as possible before timeout arrived.
#在线实例
Online demo: [http://demo.pyspider.org/debug/tutorial_pinterest](http://demo.pyspider.org/debug/tutorial_pinterest)

[PhantomJS]:           http://phantomjs.org/
标签: PySpider Python ajax
共有 人打赏支持
粉丝 0
博文 39
码字总数 36811
×
sijinge
如果觉得我的文章对您有用,请随意打赏。您的支持将鼓励我继续创作!
* 金额(元)
¥1 ¥5 ¥10 ¥20 其他金额
打赏人
留言
* 支付类型
微信扫码支付
打赏金额:
已支付成功
打赏金额: