Automated Web Scraping with Java

It’s a common strategy in any business industry to check out your competition. Investigating your direct competitors is a great way to price your goods, figure out what your customers are looking for, and even get clues on your rivals’ business strategies.

However, while standard web scraping is easy to do for just one website, things get complicated if you need to research hundreds of thousands of them.

That’s where automated web scraping with Java comes in. Java technology is the base for many types of automated web scraping, but several different Java-based web scraping tools are available on the web that all work slightly differently.

In this article, we’ll walk you through how automated web scraping works, as well as several of the best web scraping tools available today.

A Quick Introduction to Automated Web Scraping

Essentially, automated web scraping is the process by which a program isolates and compiles data from one or more websites without your intervention. One type of web scraping involves downloading the HTML of the web page in question, then searching that data for the variables you’re looking for. Your program may or may not compile the results for you after, depending on its functionality.

If you wanted to, you could easily go to a website, find the material you wanted, copy and paste it into your own dataset, and then move on with your project. Java (and other coding languages that we don’t cover here) can automate this process for you.

However, you need an interface that can handle the scraping process for you to do this. Java is just the code you use to tell the program what to do.

The advantages to automating the web scraping process like this are numerous. For one, a program can scrape websites more quickly than you ever could by hand. With a little extra coding knowledge, you can have your program automatically compile the results into easy-to-read datasets, too.

While a web scraping program will take a bit of extra time to set up initially, that time invested will pay for itself in effort over time. For example, you can easily tweak the final program to look for different data or multiple data types once you finish.

Web Scraping Tools

While you always have the option of building your own scraper tool, novice coders and programmers will find it helpful to use one of the many free web scraping tools available online. However, keep in mind that, at least as far as Java goes, there is no single “perfect” web scraping tool out there. Each has benefits and drawbacks, so make sure to pick the one that works best for what you need to do.

JSoup

JSoup is one of the most popular Java web scraping tools. It is entirely open source, meaning JSoup and its documentation are free to download and use. Jsoup is popular among users for two main reasons:

• User-friendliness – the interface is easy to learn and simple to use
• Efficiency – the JSoup program can make sense of virtually any website, even if it has messy and inefficient HTML code

JSoup uses Jquery, DOM, and CSS to isolate data from files, strings, and URLs. You’ll need either Maven or Gradle to use JSoup.

HtmlUnit

HtmlUnit is another popular Java-based web scraper. It describes itself as a “GUI-less browser,” which means it doesn’t use a specialized user interface for web scraping. Instead, it mimics a standard browser, such as Chrome, Internet Explorer, or Firefox.

Because HtmlUnit mainly uses XPath, it doesn’t always work well for JQuery-heavy web applications. However, HtmlUnit excels at anything that requires a lot of website testing since it can simulate almost anything that a real web browser can do.

Jaunt

Jaunt is another “headless” web scraper (meaning it’s GUI-free, just like HtmlUnit). With Jaunt, your Java programs can conduct DOM navigation and searching, HTTP requests and responses, and parse just about any HTML code, just like JSoup.

Essentially, Jaunt is like a combination of HtmlUnit and JSoup. However, Jaunt doesn’t support JavaScript, so you can’t use it for any applications that require it.

Selenium

Like HtmlUnit, Selenium is a browser-based administration program that was created for testing purposes, but it’s robust enough to handle web scraping as well. Unlike HtmlUnit, though, Selenium isn’t just one program, but rather a whole suite of web testing programs designed for different things.

The trouble with Selenium is that, while it’s rather powerful, you’ll have to build the web scraping program yourself. Selenium provides the programs you can use, but those are just the building blocks of your web scraping tool, not the final product.

In most cases, you’ll want to start with Selenium’s WebDriver project, but you’ll have to build or download the rest of the program’s functionality yourself. As such, we only recommend Selenium for experts.

Jauntium

Jauntium is a relatively new Java-based web scraping tool that’s based on two successful web scraping programs: Jaunt and Selenium.

It takes all of the good things about Jaunt but integrates them with JavaScript support. It also adds all of the popular features of Selenium, but with a focus on user-friendliness.

Jauntium can work in headless mode, like Jaunt, or non-headless mode like Selenium.

ui4j

ui4J is an open-source project that uses the JavaFX WebKit Engine. The program is lightweight and straightforward, and in essence, it’s just a library that turns your existing Java engine into a web scraping program. You’ll need an interface like Maven to make use of ui4j, just like with JSoup.

Conclusion

While web scraping with Java might seem like a complicated process, it’s a lot easier than you might think. As long as you take the time to learn how to use the associated web scrapers, you don’t even need too much knowledge of Java. While Java knowledge always helps, of course, the documentation included with each of these scrapers will be what helps you most.

The benefits that web scraping can provide for your project or business are worth the time invested, especially with how internet-dependent we are today. However, always keep in mind that many websites don’t take kindly to repeated web scraping, and it can actually conflict with some websites’ terms of service, so use this power sparingly!