To start using Hutool 3.9, add the following dependency to your pom.xml file (if you're using Maven):
// Current time tracking DateTime now = DateUtil.date(); // Safe wrapper around java.util.Date // Expressive formatting and parsing String customFormat = DateUtil.format(now, "yyyy-MM-dd HH:mm:ss"); DateTime parsedDate = DateUtil.parse("2026-05-28 14:00:00"); // Time delta calculation long dayDifference = DateUtil.betweenDay(now, parsedDate, true); Use code with caution. 3. Simplified Network Interaction ( hutool-http )
Version 3.9 represents the absolute peak refinement of the 3.x lifecycle, ensuring that all included APIs are fully patched and production-stable. Installation Guide
One of the most interesting aspects of the 3.9 build was its strict adherence to a zero-dependency
HttpUtil.downloadFile("https://example.com", FileUtil.file("local_data.json")); Use code with caution. Scenario B: Symmetric AES Encryption and Decryption Hutool 3.9
import com.xiaoleilu.hutool.io.FileUtil; import com.xiaoleilu.hutool.convert.Convert; import com.xiaoleilu.hutool.date.DateUtil; // 1. Read file content String content = FileUtil.readString("config.txt", "UTF-8"); // 2. Convert type Integer port = Convert.toInt(content.trim()); // 3. Get current time String now = DateUtil.now(); System.out.println("Started on port " + port + " at " + now); Use code with caution. Conclusion
: A thin wrapper over JDBC that makes database operations feel more like using an ORM without the overhead. Notable Features of Version 3.9 1. Enhanced Date Handling ( DateUtil )
was a significant milestone in the development of the Hutool Java library, a "Swiss Army Knife" designed to reduce the overhead of repetitive Java coding. Released during the 3.x lifecycle, version 3.9 focused on streamlining common development tasks like date manipulation, HTTP requests, and file I/O by providing highly efficient static methods. Core Philosophy
If you read the developer logs and contribution rules from that era, the founder openly admitted to having an extreme "obsessive-compulsive" drive for clean code. Pull requests were fiercely scrutinized for strict tab indentations and perfect JavaDoc documentation. This rigid discipline in the 3.x branch is precisely why the library gained a reputation for being remarkably bug-free. How Hutool compares to other Java Utils Feature Philosophy Hutool (e.g., 3.9 / 5.x) Apache Commons Guava (Google) Primary Goal Minimize lines of code / Make Java "sweet" Provide heavy-duty low-level components Power Google's massive infrastructure Learning Curve Extremely low (Highly semantic static methods) Moderate to high Design Style All-in-one "Swiss Army Knife" Split into dozens of specialized libraries Opinionated, functional, and strict Dependency Pure Java (Zero external dependencies in core) High (Often brings in other Google libraries) Are you looking to use Hutool in a modern project , or are you maintaining a legacy application that still relies on a 3.x version? hutool/README-EN.md at v5-master - GitHub To start using Hutool 3
: A highly intelligent type-conversion utility. It goes far beyond standard casting, allowing seamless conversion between strings, primitives, arrays, collections, and even custom Beans without throwing standard casting exceptions.
// Chainable: watch specific file pattern public WatchBuilder onFiles(String globPattern, FileHandler handler) patternHandlers.put(globPattern, handler); return this;
The foundational bedrock of the entire library. It contains utilities for basic language features, object manipulation, clone mechanisms, type conversions, and core string tools. 2. Hutool-crypto
com.xiaoleilu hutool-all 3.0.9 Use code with caution. Copied to clipboard Installation Guide One of the most interesting aspects
com.xiaoleilu hutool-all 3.3.0 Use code with caution. Example: Date Manipulation
If you are maintaining a project that requires this specific version, you can add it via Maven:
It also keeps your project lightweight. Instead of loading three different massive libraries for dates, files, and web requests, you just load Hutool. 📦 How to Add Hutool 3.9 to Your Project