Data Parsing and Scraping in Java: From Beginner to Your First Parser

Why Java, not Python? (Spoiler: the choice is not obvious)

When it comes to parsing and data scraping, Python with its BeautifulSoup and Scrapy most often comes to mind. But let's be honest: in the world of enterprise development, high-load systems, and microservices, Java remains king. If you already write in Java or are just looking at this language, then parsing in it is not just "possible," but often necessary: high speed, built-in multithreading, powerful tools for working with HTTP and HTML.

In this article, we will break down how to parse websites in Java from scratch. You will learn which libraries to use, how to avoid getting banned, and how to build your first working parser. The code examples will be as practical as possible — take them and run them.

What is Parsing and Data Scraping (and why you need it)

Before diving into the code, let's clarify the terms. Parsing is the analysis of a structure (HTML, JSON, XML) and extracting the necessary information. Scraping is the process of collecting data from web pages, which includes both parsing and downloading pages, as well as link traversal.

Why is this needed? Real-life examples:

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• Monitoring competitor prices (collecting data from online stores).
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• Collecting contacts and email addresses for B2B lead generation.
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• Automating the collection of news or posts from social networks.
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• Analyzing product reviews and ratings.
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In Java, all this is done quickly, stably, and with minimal memory consumption.

Java Toolkit for Parsing: Choosing Libraries

For parsing and data scraping in Java, there are several powerful libraries. Here is the basic set that will cover 95% of tasks:

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• Jsoup — the main library for parsing HTML. It can visit websites, extract elements using CSS selectors, and work with attributes and text.
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• Apache HttpClient or Java 11+ HttpClient — for fine-tuning requests, working with cookies, sessions, and headers.
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• Selenium WebDriver — if the site uses JavaScript to load data. It renders the page like a real browser (Chrome, Firefox).
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• OkHttp — a lightweight and fast alternative to HttpClient.
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For most static sites, Jsoup + the built-in HttpClient are sufficient. For dynamic ones, we add Selenium.

Writing Your First Parser in Java with Jsoup

Let's start simple: we'll parse article titles from a blog. Let's say we need to collect all the titles from the main page of pythonlib.ru (hypothetically).

Add the dependency in Maven (pom.xml):

<dependency>\n    <groupId>org.jsoup</groupId>\n    <artifactId>jsoup</artifactId>\n    <version>1.17.2</version>\n</dependency>

Now the code itself:

import org.jsoup.Jsoup;\nimport org.jsoup.nodes.Document;\nimport org.jsoup.nodes.Element;\nimport org.jsoup.select.Elements;\n\npublic class SimpleParser {\n    public static void main(String[] args) {\n        try {\n            // 1. Load the page\n            Document doc = Jsoup.connect("https://pythonlib.ru")\n                    .userAgent("Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36")\n                    .timeout(10000)\n                    .get();\n\n            // 2. Select all h2 titles (or any other selector)\n            Elements headlines = doc.select("h2.entry-title a");\n\n            // 3. Print the text and links\n            for (Element headline : headlines) {\n                String title = headline.text();\n                String link = headline.attr("href");\n                System.out.println("Title: " + title);\n                System.out.println("Link: " + link);\n                System.out.println("---");\n            }\n\n        } catch (Exception e) {\n            e.printStac