the self-cultivation of reptiles _4I. Introduction to the SCRAPY framework
Scrapy is an application framework written with pure Python for crawling Web site data and extracting structural data, which is very versatile.
The power of the framework, users only need to customize the development of a few modules can be easily implemented a crawler, used to crawl Web content and a variety of pictures, very convenient.
Scrapy uses the Twisted [‘tw?st?d] (its main opponent is Tornado) a
(shown by the green arrows). Here is a brief description of each component and a link to the detailed content. The data flow is described below
Paste_image.png
Component
Scrapy EngineThe engine is responsible for controlling the flow of data across all components in the system and triggering events when the corresponding action occurs. For more information, see the Data Flow section below.
Scheduler (Scheduler)The scheduler accepts the request from the engine and queue them up so that
for controlling the flow of data in all components of the system and triggering events when the corresponding action occurs. See the Data Flow section below for more information.
This component is equivalent to the "brain" of a reptile, the dispatch center of the entire reptile. Scheduler (Scheduler)
The scheduler accepts requests from the engine and takes them on the team so that the engine can be supplied to the engine upon request.
The initial crawl URL and subsequent URLs that are fetched i
a lot of learning python programming language friends will learn python web crawler technology, but also specialized in web crawler technology, then how to learn python crawler technology, Let's talk today about the very popular python crawl framework scrapyusing python to crawl data, Next, learn the architecture of scrapy to make it easier to use this tool. I. OverviewShows the general architecture of Scrapy , which contains its main components and the data processing flow of the system (shown
I. OverviewShows the general architecture of Scrapy, which contains its main components and the data processing flow of the system (shown by the green arrows). The following will explain the role of each component and the process of data processing.Second, the component1. Scrapy engine (Scrapy engines)The Scrapy engine is used to control the data processing flow of the entire system and to trigger transactions. More detailed information can be found in the following data processing process.2, Sc
inevitably encounter some needs, we need to modify the image of the cache path.
Analysis:
We notice that the Picasso bottom is actually using okhttp to download the picture, and there is a. Downloader (Downloader Downloader) method when setting up the Picasso. We can pass in a okhttpdownloader (...).
Realize:
1. Method One
Okhttp dependence
Compile ' com.squareu
Scrapy uses the Twisted asynchronous network library to handle network traffic.The overall structure is broadly as follows (note: Images from the Internet):1. Scrapy engine (Scrapy engines)The Scrapy engine is used to control the data processing flow of the entire system and to trigger transactions. More detailed information can be found in the following data processing process.2, Scheduler (Dispatch)The scheduler accepts requests from the Scrapy engine and sorts them into queues and returns the
1, overview
Scrapy is an application framework written with pure Python for crawling Web site data and extracting structural data, which is very versatile.
The power of the framework, users only need to customize the development of a few modules can be easily implemented a crawler, used to crawl Web content and a variety of pictures, very convenient.
Scrapy uses the twisted[' tw?st?d] (its main opponent is Tornado), the asynchronous network framework to handle network traffic, c
, then the above code is no way; ③ again, for example, we want to download a variety of images, for different site sources have different ways to download .... These special needs tell us that the above code is completely out of the way. So for the completeness and scalability of the control, we need a configurator, a monitor, a downloader. And so on special needs to add the plug-in development. Therefore, we can see that under the Org.kymjs.aframe.bi
can be downloaded gradually.
The following is a self-tested streaming media playback and download Tutorial:
1. Build the interface ()
2. Third-Party assistant classes used
: Http://pan.baidu.com/s/1hrvqXA8
3. Start the project-header files and related macros
LO_ViewController.h
#import
#import
#import "M3U8Handler.h"#import "VideoDownloader.h"#import "HTTPServer.h"@interface LO_ViewController : UIViewController
@property (nonatomic, strong)HTTPServer * httpServer;@propert
, as requests.
URL who will prepare it? It looks like the spider is preparing itself, so you can guess that the Scrapy architecture section (not including the spider) mainly does event scheduling, regardless of the URL's storage. Looks like the Gooseeker member center of the crawler Compass, for the target site to prepare a batch of URLs, placed in the compass ready to perform crawler operation. So, the next goal of this open source project is to put the URL management in a centralized disp
structure is broadly as followsScrapy mainly includes the following components:
Engine (scrapy): Used to handle the entire system of data flow processing, triggering transactions (framework core)
Scheduler (Scheduler): Used to accept requests sent by the engine, pressed into the queue, and returned when the engine was requested again. It can be imagined as a priority queue for a URL (crawling the URL of a Web page or a link), which determines what the next URL to crawl is, and remo
duplicate URLs
Downloader (Downloader)Used to download Web content and return Web content to spiders (Scrapy downloader is built on twisted, an efficient asynchronous model)
Reptile (Spiders)Crawlers are primarily working to extract the information they need from a particular Web page, the so-called entity (Item). The user can also extract a link from it
a Web page or a link), which determines what the next URL to crawl is, and removes duplicate URLs
Downloader (Downloader)Used to download Web content and return Web content to spiders (Scrapy downloader is built on twisted, an efficient asynchronous model)
Reptile (Spiders)Crawlers are primarily working to extract the information they need from a particu
crawl, and removes the duplicate URLs
Downloader (Downloader)used to download Web content and return Web content to spiders (Scrapy downloader is built on twisted, an efficient asynchronous model)
Reptile (Spiders)crawlers are primarily working to extract the information they need from a particular Web page, the so-called entity (Item). The user can also
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