How to use maven to implement Jsoup crawler
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First, a brief introduction to Jsoup
Jsoup is a Java HTML parser that can directly parse a URL address and HTML text content. It provides a very labor-saving API that can fetch and manipulate data through DOM,CSS and jQuery-like operations.
What can we do with Jsoup
2.1 scrape and parse HTML to find and extract data from URL, files, or strings
2.2 manipulate HTML elements, attributes, and text using DOM traversal or CSS selectors
2.3 so that we can output the neat text we want
Third, use Jsoup to crawl an example
As can be seen from the picture, we can successfully crawl the title of the popular sales of women's wear from high to low, so that we can analyze the title name of high sales (or comprehensive ranking) in the front column. Thus, the naming rules of popular goods can be analyzed.
IV. Jsoup usage
4.1First, create maven project and inject dependency on maven project
4.2Dependencies need to be imported after injecting dependencies, otherwise using Jsoup in the program will report all errors.
4.3 use the knowledge of JSP to find the target elements
If we find that the ID of the target page is "plist" at some east interface, then we use the
GetElementById ("plist"); method to get his ID
Then get the target title, which can be analyzed from the image above, and the title is controlled by the tag, so we need to use
GetElementsByTag ("em"); to capture the part of em
Finally, loop out his part.
V. Summary
Jsoup can only be used for simple page capture, in actual development, many websites use Ajax technology to make the module in the dynamic change or anti-crawler technology, so this technology has limitations. Students who are familiar with front-end jsp technology should be able to handle it.
Finally, all the codes are attached.
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