Web Scraping with Java in 2023

You found a good website and now, you want to extract data from the webpage to excel. How would you do that? Copy-pasting is so vintage, especially with interesting web scraping tools available online.

Web scraping is the process of automatically extracting data from websites. Java is one of the languages used to build web scraping APIs. You can use Java to handle complex web scraping tasks, handle large amounts of data and build custom web scraping applications.

In this java web scraping tutorial, we’ll see how to use Java to scrape webpages easily using the popular Jsoup library and other essential tools. So, grab your favorite text editor, fire up your JVM, and let’s get started!

Extract text from any webpage in just one click. Head over to Nanonets website scraper, Add the URL and click “Scrape,” and download the webpage text as a file instantly. Try it for free now.

Why use Java for web scraping?

Java is a good choice for web scraping for the following reasons:

• It is versatile and has a large number of web scraping libraries and frameworks, which make it easy to use.
• Java can handle custom web scraping tasks with higher complexity and offer greater automation as compared to other languages.
• Java has strong support for multithreading. This allows you to scrape multiple web pages simultaneously.
• Java has great data analytics and processing support, which is crucial for handling large data sets.

Some things to keep in mind while using Java for web scraping:

• Use Jsoup or Selenium web scraping libraries to simplify the scraping process.
• Use a powerful proxy server or rotate IP addresses to avoid being blocked.
• Use a scalable architecture that can handle large volumes of data and is easy to maintain over time.

How to scrape website data using Java?

• Step 1: Set up the environment
• Step 2: Inspect the page you want to scrape
• Step 3: Send an HTTP request and scrape the HTML
• Step 4: Extracting specific sections
• Step 5: Export the data to CSV.

Step 1: Set up the environment

In order to get started, create a new project and import the required Java libraries:

• Jsoup: A great library to work with parse HTML and extract data from websites.
• Apache Commons Lang: Provides a complete set of utilities for working with strings, arrays, and other common data types.

You can use Maven or Gradle to manage the dependencies. Here’s how you can add dependencies using Maven

<dependencies>
<dependency>
<groupId>org.jsoup</groupId>
<artifactId>jsoup</artifactId>
<version>1.14.3</version>
</dependency>
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-lang3</artifactId>
<version>3.12.0</version>
</dependency>
</dependencies>

Step 2: Inspect the page you want to scrape

Right-click the page that you want to scrape and select inspect element. Check all the names of the elements to scrape them properly.

Step 3: Send HTTP request

You need to send an HTTP request to the server in order to scrape data from the web page. Use the Java HttpURLConnection class to send HTTP to connect requests.

Here’s how to do it:

String url = "https://www.example.com";
URL obj = new URL(url);
HttpURLConnection con = (HttpURLConnection) obj.openConnection();
// optional request header
con.setRequestProperty("User-Agent", "Mozilla/5.0");
int responseCode = con.getResponseCode();
System.out.println("Response code: " + responseCode);
BufferedReader in = new BufferedReader(new InputStreamReader(con.getInputStream()));
String inputLine;
StringBuilder response = new StringBuilder();
while ((inputLine = in.readLine()) != null) {
response.append(inputLine);
}
in.close();
String html = response.toString();

What is happening in the code?

In the code above, we create a new URL object. And we try to open a connection to its server using HttpURLConnection. We’ve included our identifier as Mozilla Firefox. Finally, we then read the received response from the server using BufferedReader. We append each input line to StringBuilder to convert it into a readable string.

Step 4: Parse the HTML document

In this step, we will parse the HTML document using JSoup. We can select the elements of the webpage that we want to extract by using tag name, class, or ID, and traversing the DOM tree.

Here is the code to use Jsoup to parse HTML.

Document doc = Jsoup.parse(html);
Elements links = doc.select("a[href]");
for (Element link : links) {
String href = link.attr("href");
System.out.println(href);
}

In this code snippet, we first create a new Jsoup Document object from the HTML string. We then use the select method to select all links on the page by their href attribute. We iterate over the links and extract the value of the href attribute using the attr method.

Step 5: Save the data to a CSV

Once we’ve extracted the data we’re interested in, we can save it to a file or database for further analysis. In this example, we’ll save the links to a CSV file using the Apache Commons CSV library.

Writer writer = Files.newBufferedWriter(Paths.get("links.csv"));
CSVPrinter csvPrinter = new CSVPrinter(writer, CSVFormat.DEFAULT);

Extract text from any webpage in just one click. Head over to Nanonets website scraper, Add the URL and click “Scrape,” and download the webpage text as a file instantly. Try it for free now.

What are the advantages of using Java for web scraping?

• Powerful libraries: Java offers several powerful libraries, such as JSoup and HtmlUnit, that simplify the web scraping process and make it more efficient. These libraries provide easy-to-use APIs for parsing HTML, making network requests, and handling JavaScript, cookies, and AJAX.
• Multi-platform compatibility: Java is a platform-independent language that runs on various operating systems and architectures. This compatibility makes Java a versatile choice for web scraping tasks, as your code can be easily run and deployed on different platforms.
• Excellent performance: Java is known for its performance, which is especially important when handling large-scale web scraping tasks. Java’s just-in-time (JIT) compilation and garbage collection ensure that your web scraping code runs efficiently, even when dealing with large amounts of data or complex websites.
• Strong typing and error-checking: Java’s strong typing and compile-time error checking can help prevent bugs and runtime errors in your web scraping code. This feature makes it easier to catch potential issues before deploying your scraper, leading to more stable and reliable code.
• Large community and ecosystem: Java has a vast community of developers and a rich ecosystem of libraries and frameworks, which means you can find solutions, support, and resources for almost any problem you might encounter during web scraping.

What are the drawbacks of using Java for web scraping?

• Steeper learning curve: Java can be more challenging than other languages like Python, especially for beginners. Its syntax and concepts might be harder to grasp for those new to programming or web scraping.
• Verbosity: Java is a verbose language, which can make web scraping code longer and more complex than in other languages like Python. This verbosity can lead to an increase in development time and make it more challenging to read and maintain the code.
• Boilerplate code: Java often requires a significant amount of boilerplate code to set up classes, objects, and methods. This can lead to repetitive and cumbersome code, slowing the development process.
• Less focus on web scraping: While Java has powerful libraries, the language itself is not specifically designed for web scraping tasks. Languages like Python, with dedicated web scraping libraries like Beautiful Soup and Scrapy, might focus more on web scraping tasks and provide a more streamlined experience.
• Lack of modern language features: Java has been around for a long time, and while it continues to evolve, some modern language features, like those found in Python or JavaScript, are not present in Java. These features could make web scraping tasks more efficient and easier to implement.

Extract text from any webpage in just one click. Head over to Nanonets website scraper, Add the URL and click “Scrape,” and download the webpage text as a file instantly. Try it for free now.

Conclusion

Java offers several advantages for web scraping, including powerful libraries, multi-platform compatibility, and excellent performance. However, it also has drawbacks, such as a steeper learning curve, verbosity, and less focus on web scraping compared to other languages like Python.

Carefully consider your project requirements, experience, and preferences when deciding which language to use for web scraping. By following the steps outlined in this article, along with the examples and illustrations provided, you can easily set up a web scraping project using Java and start extracting valuable data from websites.

Another alternative is to use automated website scraping tools like Nanonets. You can use the free website-to-text tool. But, if you need to automate web scraping for larger projects, you can contact Nanonets.

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Source: https://nanonets.com/blog/java-web-scraping-tutorial/