Upgrade Guide
To upgrade to Hutool 3.9, follow these steps:
Conclusion
Hutool 3.9 brings significant updates and improvements to the library. The new hutool.crypto module, improved performance, and enhanced support for Java 11 and later make this update a must-have for Hutool users. We recommend upgrading to Hutool 3.9 to take advantage of these new features and improvements.
Changelog
References
Based on the version numbering conventions of the Hutool project, there is no official release versioned "3.9". The Hutool project skipped from version 3.x (3.2.x) directly to 4.x (4.0.0) around late 2017/early 2018.
It is highly probable that you are either:
Below is a report on the transition from Hutool 3.x to 4.x (the likely "upgrade" path from a 3.9 concept), and an overview of the library's capabilities.
In the ever-evolving ecosystem of Java development, few libraries have achieved the quiet ubiquity of Hutool. Dubbed the "Java Sweet Tool," Hutool has, since its inception, aimed to reduce boilerplate code and wrap complex JDK operations into simple, chainable methods. While newer versions (4.x, 5.x, and 6.x) exist, the Hutool 3.9 UPD (Update) remains a legendary milestone for developers stuck on legacy Java 8 or those who value stability over rapid iteration.
Released as the final major feature update of the 3.x branch, Hutool 3.9 wasn't just a patch—it was a paradigm shift. This article dissects every major component of the 3.9 update, explaining why it remains relevant, how to migrate to it, and the specific "UPD" features that changed Java utility coding forever.
If you are maintaining a legacy system:
Maven Coordinates (Current Standard):
<dependency>
<groupId>cn.hutool</groupId>
<artifactId>hutool-all</artifactId>
<version>5.8.26</version> <!-- Or latest 6.x -->
</dependency>
The Convert class in Hutool 3.9 received its most significant upgrade. Previously, conversion between primitive arrays, collections, and strings was cumbersome.
New in 3.9 UPD:
// Hutool 3.9 UPD example
int[] intArray = 1, 2, 3;
String str = Convert.toStr(intArray); // Previously returned null; now returns "[1, 2, 3]"
Months later, Lina was promoted. In her farewell speech, she raised a cup of coffee and said:
"Thank you, Hutool. You taught me that even the sharpest tool can slip. And that's okay—as long as you have a patch, a plan, and people who care enough to fix it."
Old Kai nodded from the back. He had already updated to Hutool 4.0, but he kept a copy of 3.9.1 in his .m2/repository—not for the code, but for the memory.
The stack trace that almost broke the city. And the quiet patch that saved it.
The end.
Hutool 3.9 UPD represents a legacy yet pivotal version of the popular Java utility library Hutool, widely recognized for its "sweet" approach to simplifying Java development. While modern versions have advanced to the 5.x branch, the 3.9 update remains a point of reference for developers maintaining older systems or transitioning legacy codebases. Overview of Hutool 3.9 UPD
Hutool is a comprehensive Java toolset designed to reduce the cost of learning complex APIs and increase developer productivity. The "UPD" (Update) in version 3.9 focused on refining the core library to eliminate common boilerplate code through static method encapsulation. Key Focus Areas for 3.9:
Performance Optimization: Significant internal refactoring to speed up common string and collection operations.
JSON Support: Enhanced handling of JSON data, providing more flexible parsing and generation tools.
Cryptographic Enhancements: Expanded capabilities in the hutool-crypto module, offering better support for symmetric and asymmetric algorithms. Core Modules in Hutool
The 3.9 release maintained the modular architecture that allows developers to include only what they need: Hutool 3.9 UPD
hutool-core: The foundation, covering Bean operations, dates, and various utility classes.
hutool-http: A lightweight HTTP client that simplifies web requests.
hutool-poi: Streamlines complex Excel and Word operations using Apache POI.
hutool-crypto: Simplifies encryption, decryption, and digest algorithms.
hutool-db: Offers database operations based on ActiveRecord thinking. Why Version 3.9 Matters
Version 3.9 was one of the final major releases before the library underwent significant structural changes in subsequent branches. It is frequently cited in automotive engineering contexts—specifically for tools like HU Tool 3.9 used in BMW coding and SSH enabling—though this is a distinct, specialized tool unrelated to the general-purpose Java Hutool library. hutool/README-EN.md at v5-master - GitHub
Hutool version 3.9 is an older release of the popular Java utility library. The Hutool project is currently maintained in v5-master, with newer releases significantly expanding its modular capabilities.
The 3.9 series (specifically 3.9.0) focused on broadening the library's utility across core Java functions, providing "sweeter" alternatives to standard library code. Key Updates in Hutool 3.9
Enhanced Bean Tools: Improvements were made to BeanUtil, specifically regarding more flexible property copying and deep conversion between Java beans and maps.
Expanded IO & File Utilities: Additions to IoUtil and FileUtil aimed at reducing the verbosity of stream handling and file system operations, such as more robust directory walking and faster stream piping.
Cryptographic Improvements: Enhancements to the SecureUtil facade provided simpler entry points for MD5, SHA-256, and AES/DES encryption routines, following the project's goal of replacing complex boilerplate with single-function calls.
Collection Tooling: Refinements in CollUtil added better support for filtering, transformation, and empty-safe operations on standard Java collections. Project Context
Hutool is designed as a "small and full" Java toolset that encapsulates commonly used code into static methods.
Core Modules: The library is divided into modules like hutool-core (basic tools), hutool-log (logging facade), and hutool-setting (enhanced properties).
Evolution: While v3.9 established many of these core patterns, developers are now encouraged to use the v5.x branch available on the Hutool GitHub repository for better performance and support for modern Java versions. hutool/README-EN.md at v5-master - GitHub
, a professional software package used for BMW vehicle diagnostics, coding, and service history management
This tool is widely used by automotive technicians for BMW "Head Unit" (HU) and "Multimedia Graphics Unit" (MGU) systems. Key Features of Hutool 3.9 MGU Bench Programming : Supports programming MGU units on a bench setup. Service History Management
: Allows users to read current service history from the car, write new entries, and edit existing service records. FSC Map Generation
: Includes tools for generating "Navigation Map Update" (FSC) codes. USB Coding & Activations
: Provides advanced coding solutions via USB for various BMW infotainment features. Practical Guide for Use Hardware Connection
: Most advanced programming (like MGU "No-Solder") requires specific connection adapters to link the unit to your PC. Activation & Licensing
: The software is typically licensed per PC. Users must provide a serial number and activation code to register the tool. Software Updates
: Updates are managed through a dedicated platform where users can enter renewal activation codes to extend their subscription service. Service History Updates
: When writing a new service entry, the tool adds the new record to the top of the existing list in the vehicle's internal database.
For more technical details or to purchase the license, users typically visit specialized automotive platforms like BlackBOX Sistemi or community-led groups like the BMW HU & MGU Engineering Tools connection diagrams for a particular BMW model? USER MANUAL - XTOOLTECH Upgrade Guide To upgrade to Hutool 3
The 3.9 update introduced several performance improvements and architectural changes to keep the library efficient:
hutool-crypto Module: A major addition that centralized cryptographic functions like symmetrical and asymmetrical encryption, hashing, and signature tools.
Java 11 Compatibility: Enhanced support was added to ensure smoother integration with Java 11 environments.
Performance Tuning: General optimizations were applied across the library to reduce overhead in high-throughput applications. Key Sub-Module Structure
Hutool is designed as a modular library, allowing developers to import specific tools or the entire suite via the Hutool-all package:
hutool-core: The foundation, covering bean operations, date manipulation, and general file/IO utilities.
hutool-db: Simplifies database operations using an "ActiveRecord" approach to minimize JDBC boilerplate.
hutool-extra: Provides wrappers for third-party tools, such as template engines, mail clients, QR code generators, and FTP services.
hutool-system: Tools for retrieving system parameters like JVM information. Usage and Availability
Developers primarily use Hutool to replace custom "util" packages, reducing the risk of bugs from poorly maintained internal wrappers. For the most up-to-date documentation and installation guides, visit the official Hutool Documentation. hutool/README-EN.md at v5-master - GitHub
Exploring Hutool 3.9: Key Updates and Performance Enhancements
In the ecosystem of Java development, efficiency is often measured by how much "boilerplate" code you can eliminate. For years, Hutool has stood out as a premier "Swiss Army Knife" for Java developers, providing a comprehensive set of utilities that simplify everything from file manipulation to cryptographic operations.
The release of Hutool 3.9 marked a significant milestone in the library’s evolution, focusing on refining core tools and expanding support for modern development workflows. Here is a deep dive into the most impactful updates in version 3.9. 1. Strengthened Cryptography (Crypto) Module
One of the most notable UPD (updates) in 3.9 is the enhancement of the Hutool-crypto package. Security requirements are constantly shifting, and version 3.9 addressed this by:
BCrypt Support: Improved implementation of the BCrypt hashing algorithm, making it easier to handle secure password storage with built-in salting.
SM2/SM3/SM4 Optimization: For developers working with Chinese national standard (Guomi) algorithms, 3.9 provided better stability and performance for these specific cryptographic ciphers. 2. Enhanced HTTP Client Capabilities
Hutool-http is often preferred over heavier libraries like Apache HttpClient for its simplicity. In 3.9, several refinements were made to the HttpRequest and HttpResponse classes:
Timeout Handling: More granular control over connection and read timeouts.
Cookie Management: Refined automated cookie handling, allowing for more seamless session persistence during multi-step web scraping or API testing. 3. Date and Time Utilities (DateUtil)
The DateUtil class is perhaps the most used part of Hutool. The 3.9 update focused on "safety" and "localization":
Parsing Robustness: Version 3.9 introduced smarter string-to-date parsing, capable of identifying more esoteric date formats without requiring explicit pattern strings.
Performance: Internal optimizations reduced the overhead when performing massive batch conversions of timestamps. 4. File and IO Improvements
Working with files in Java can be notoriously verbose. Hutool 3.9 streamlined this further:
WatchMonitor Enhancements: The file monitoring utility became more stable, particularly on Windows environments, reducing the "missed event" bug that occasionally plagued earlier versions.
Tailer Functionality: Improvements to the Tailer class allowed for smoother real-time log monitoring (similar to the Linux tail -f command). 5. Bean and Reflection Utilities Conclusion
Hutool 3
The mapping of data between objects (Beans) is a daily task for backend engineers.
CopyOptions: 3.9 introduced more flexible CopyOptions, allowing developers to ignore specific properties or handle null values with greater precision during bean copying.
Reflection Performance: By caching more metadata internally, ReflectUtil saw a measurable speed boost when accessing private fields and methods. Why the 3.9 Update Mattered
While newer versions (like Hutool 5.x and 6.x) have since been released, the Hutool 3.9 UPD was a "stabilization" release. It bridged the gap between the older Java 7 paradigms and the more modern, streamlined Java 8+ coding styles. It ensured that the library remained lightweight (under 10MB) while offering features that usually require five or six separate dependencies. Summary of Key Changes Update Highlight JSON
Faster parsing and better support for nested Map structures. Setting Added support for more flexible configuration file formats. System
Better detection of JVM and OS-level environmental variables. How to Update
If you are still maintaining legacy projects using the 3.x branch, ensure your pom.xml reflects the update:
Hutool 3.9 remains a testament to the library's philosophy: "Small yet complete." It simplified the complex, standardized the scattered, and helped Java developers get back to writing business logic instead of utility methods.
The request for a "long piece for Hutool 3.9 UPD" likely refers to the legacy v3.x series
, a comprehensive Java tool library. While the library is currently in its v5.x and v7.x (milestone) stages, the v3.9.x updates were critical milestones that established its "no-dependency" philosophy and core module structure.
Below is an overview of the significance and key features of the Hutool 3.9 updates. 1. The v3.9.x Philosophy: "Small but Complete"
Hutool 3.9 focused on stabilizing the library's foundation. During this era, the project transitioned into a more modularized structure, ensuring that developers could include only what they needed (e.g., hutool-core hutool-http hutool-json ) to keep the final JAR size minimal. 2. Core Module Enhancements
The 3.9 update introduced and refined several "sweet" features that remain staples of the library today: Hutool-Core (The Foundation): StrUtil & ReUtil:
Major performance improvements for string manipulation and regex extraction.
Simplified type conversion (e.g., converting a String to a Date or a Map to a Bean) became significantly more robust.
Enhanced "Copy Properties" functionality, allowing for deep and shallow copies between POJOs with minimal configuration. Hutool-Http (Lightweight Networking): This version prioritized a simple HttpUtil.get() HttpUtil.post()
interface, providing a lightweight alternative to heavier libraries like Apache HttpClient or OkHttp for standard REST calls. Hutool-Json: Improvements to
allowed for seamless conversion between JSON strings, Maps, and Java Beans, specifically handling complex nested objects better than earlier 3.x versions. 3. Key API Improvements in 3.9 The "UPD" (Update) cycle for 3.9 specifically addressed: Java 8 Compatibility: Better support for LocalDateTime types within the conversion and formatting utilities. Security Fixes: Patching vulnerabilities in the (task scheduling) and to prevent path traversal issues. Global Exception Handling: Standardizing how the library throws UtilException
and its subclasses to provide clearer stack traces for debugging. 4. Legacy Context
If you are looking for specific documentation for this version, it is important to note that the official Hutool site Maven Central
Using the new CronUtil in 3.9 UPD:
CronUtil.schedule("0 0 2 * * *", () ->
FileUtil.clean(FileUtil.file("/temp/logs"));
);
CronUtil.start(); // Runs a lightweight cron scheduler inside your JVM.
The announcement echoed through Maven Central like a town crier’s bell:
Hutool 3.9 is released! New features, better performance, and cleaner APIs!
The developers rejoiced. They updated their pom.xml files, ran mvn clean install, and watched their tests turn green. The release was smooth. Too smooth.