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+---
+title: regions4j
+---
+
+## Introduction
+
+**regions4j** is a lightweight, type-safe Java library that provides comprehensive metadata for world regions based on the ISO 3166-1 standard. It is designed to simplify internationalisation (i18n), telecommunication routing, and regional data management in Java-based enterprise applications.
+
+The library models every ISO 3166-1 country and territory as an enum constant, giving you compile-time safety and IDE autocompletion when referencing regions. With built-in O(1) lookups, zero external dependencies, and Java 8 compatibility, it is suitable for projects of any size — from microservices to monolithic enterprise systems.
+
+## Features
+
+- **ISO 3166-1 Compliant** — Full support for Alpha-2 (`abbreviation`) and Alpha-3 (`code`) formats across all assigned countries and territories.
+- **Telecommunication Metadata** — Includes E.164 international dialling prefixes for every region.
+- **Locality Support** — Default locale tags (`zh_HK`, `en_US`, `en_GB`, etc.) for each region to assist with i18n workflows.
+- **High Performance** — Thread-safe, immutable internal hash maps provide constant-time lookups by abbreviation or code.
+- **Zero Dependencies** — A pure Java library with no external overhead.
+- **Calendar Versioning** — Versions follow a `YYYY.MM` scheme (e.g. `2025.12`) to transparently indicate the freshness of the underlying ISO data, rather than semantic versioning.
+
+## Core Schema
+
+Each region exposes four attributes:
+
+| Attribute      | Type   | Description                     | Example                            |
+|----------------|--------|---------------------------------|------------------------------------|
+| `abbreviation` | String | ISO 3166-1 alpha-2 abbreviation | `HK`, `US`, `GB`, `RU`             |
+| `code`         | String | ISO 3166-1 alpha-3 code         | `HKG`, `USA`, `GBR`, `RUS`         |
+| `callingCode`  | String | E.164 international dialling prefix | `852`, `1`, `44`, `7`              |
+| `locale`       | String | Default language and region tag | `zh_HK`, `en_US`, `en_GB`, `ru_RU` |
+
+## Installation
+
+**Maven:**
+
+```xml
+<dependency>
+    <groupId>com.onixbyte</groupId>
+    <artifactId>regions4j</artifactId>
+    <version>2025.12</version>
+</dependency>
+```
+
+**Gradle (Kotlin DSL):**
+
+```kotlin
+implementation("com.onixbyte:regions4j:2025.12")
+```
+
+> **Versioning note:** This library uses Calendar Versioning (`YYYY.MM`) rather than Semantic Versioning. A version string like `2025.12` tells you immediately that the regional data reflects the ISO 3166-1 state as of December 2025.
+
+## Usage
+
+### Direct Access
+
+Reference any region directly via its enum constant:
+
+```java
+Region uk = Region.UNITED_KINGDOM;
+
+uk.getAbbreviation(); // "GB"
+uk.getCode();         // "GBR"
+uk.getDialCode();     // "44"
+uk.getLocale();       // "en_GB"
+```
+
+### Efficient Lookups
+
+Look up regions from string inputs — ideal for processing web requests, API payloads, or database records:
+
+```java
+// By Alpha-2 abbreviation (case-sensitive)
+Region region = Region.fromAbbreviation("HK");
+
+// By Alpha-3 code (case-insensitive)
+Region region = Region.fromCode("HKG");
+```
+
+### Java Locale Integration
+
+Convert a region's locale string to a `java.util.Locale` for use with standard Java i18n APIs:
+
+```java
+Region region = Region.CHINA;
+Locale javaLocale = Locale.forLanguageTag(region.getLocale().replace("_", "-"));
+javaLocale.getDisplayCountry(Locale.UK); // "China"
+```
+
+## Performance
+
+On first access, the library initialises all regions into immutable `HashMap` structures. Subsequent lookups via `fromAbbreviation()` and `fromCode()` are thread-safe and run in constant time — suitable for high-throughput request paths.
+
+## Requirements
+
+- Java 8 or later
+
+## License
+
+regions4j is open-source software released under the MIT License.
diff --git a/docs/zh-hans/projects/regions4j/index.mdx b/docs/zh-hans/projects/regions4j/index.mdx
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+---
+title: regions4j
+---
+
+## 介绍
+
+**regions4j** 是一个轻量级、类型安全的 Java 库，基于 ISO 3166-1 标准提供全面的世界地区元数据。它旨在简化 Java 企业应用中的国际化（i18n）、电信路由和地区数据管理工作。
+
+该库将每个 ISO 3166-1 国家和地区建模为枚举常量，使您在引用地区时获得编译期安全性和 IDE 自动补全支持。凭借内置的 O(1) 查找、零外部依赖和 Java 8 兼容性，它适用于任何规模的项目 — 从微服务到整体式企业系统。
+
+## 特性
+
+- **ISO 3166-1 合规** — 完整支持所有已分配国家和地区的 Alpha-2（`abbreviation`）和 Alpha-3（`code`）格式。
+- **电信元数据** — 包含每个地区的 E.164 国际拨号前缀。
+- **区域支持** — 每个地区提供默认的区域标签（如 `zh_HK`、`en_US`、`en_GB` 等），辅助 i18n 工作流。
+- **高性能** — 线程安全、不可变的内部哈希映射提供常量时间的缩写或代码查找。
+- **零依赖** — 纯 Java 库，无任何外部依赖。
+- **日历化版本管理** — 版本号采用 `YYYY.MM` 格式（如 `2025.12`），以透明地反映底层 ISO 数据的新鲜度，而非语义化版本号。
+
+## 核心数据模型
+
+每个地区暴露四个属性：
+
+| 属性 | 类型 | 描述 | 示例 |
+|---|---|---|---|
+| `abbreviation` | String | ISO 3166-1 alpha-2 缩写 | `HK`、`US`、`GB`、`RU` |
+| `code` | String | ISO 3166-1 alpha-3 代码 | `HKG`、`USA`、`GBR`、`RUS` |
+| `callingCode` | String | E.164 国际拨号前缀 | `852`、`1`、`44`、`7` |
+| `locale` | String | 默认语言和地区标签 | `zh_HK`、`en_US`、`en_GB`、`ru_RU` |
+
+## 安装
+
+**Maven:**
+
+```xml
+<dependency>
+    <groupId>com.onixbyte</groupId>
+    <artifactId>regions4j</artifactId>
+    <version>2025.12</version>
+</dependency>
+```
+
+**Gradle (Kotlin DSL):**
+
+```kotlin
+implementation("com.onixbyte:regions4j:2025.12")
+```
+
+> **版本说明：** 该库使用日历化版本管理（`YYYY.MM`）而非语义化版本号。版本字符串如 `2025.12` 可以直观地告诉您地区数据反映的是 2025 年 12 月的 ISO 3166-1 状态。
+
+## 使用
+
+### 直接访问
+
+通过枚举常量直接引用任何地区：
+
+```java
+Region uk = Region.UNITED_KINGDOM;
+
+uk.getAbbreviation(); // "GB"
+uk.getCode();         // "GBR"
+uk.getDialCode();     // "44"
+uk.getLocale();       // "en_GB"
+```
+
+### 高效查找
+
+从字符串输入中查找地区 — 非常适合处理 Web 请求、API 负载或数据库记录：
+
+```java
+// 按 Alpha-2 缩写查找（区分大小写）
+Region region = Region.fromAbbreviation("HK");
+
+// 按 Alpha-3 代码查找（不区分大小写）
+Region region = Region.fromCode("HKG");
+```
+
+### Java Locale 集成
+
+将地区的 locale 字符串转换为 `java.util.Locale` 以配合标准 Java i18n API 使用：
+
+```java
+Region region = Region.CHINA;
+Locale javaLocale = Locale.forLanguageTag(region.getLocale().replace("_", "-"));
+javaLocale.getDisplayCountry(Locale.UK); // "China"
+```
+
+## 性能
+
+首次访问时，库会将所有地区初始化到不可变的 `HashMap` 结构中。后续通过 `fromAbbreviation()` 和 `fromCode()` 进行的查找均为线程安全且以常量时间运行 — 适用于高吞吐量的请求路径。
+
+## 要求
+
+- Java 8 或更高版本
+
+## 许可证
+
+regions4j 是采用 MIT 许可证发布的开源软件。