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Showing posts with the label 工具方法

A New Collection of Thoughtful Learning Apps — Now Available on iOS & Android

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I’m excited to share a set of mobile apps I’ve recently completed and published on both the Google Play Store and the Apple App Store. These apps are designed with a simple goal in mind: to make meaningful, structured content more accessible, whether you’re studying theology or improving your English vocabulary. 📱 Now Available on Both Platforms All apps are live and available for download: Google Play Developer Page: https://play.google.com/store/apps/dev?id=5835943159853189043 Apple App Store Developer Page: https://apps.apple.com/ca/developer/q-z-l-corp/id1888794100 📖 Theology & Confession Study Apps For those interested in Reformed theology and classical Christian teachings, I’ve developed a series of apps that present foundational texts in a clean, focused reading format: The Belgic Confession Canons of Dort Heidelberg Catechism Westminster Shorter Catechism Each app is designed to provide a distraction-free experience, making it easier to read, reflect, and revisit these im...
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Java如何安全按字节长度截断String（UTF-8完整解决方案）

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Java如何安全按字节长度截断String（UTF-8完整解决方案） 在Java开发中，我们经常需要对字符串进行长度限制，比如： 数据库字段有字节长度限制 接口参数有大小限制 日志或消息需要截断 很多人第一反应是使用： value.substring(0, n) 但这种方式在涉及 UTF-8 编码 时是 不安全的 。 问题本质：字符长度 ≠ 字节长度 在 UTF-8 编码中： 英文字符 → 1 byte 中文字符 → 3 bytes Emoji → 4 bytes 例如： "hello" → 5 bytes "你好" → 6 bytes "😊" → 4 bytes 因此： substring 按字符截断，无法控制字节大小 --- Java 标准库有没有现成方法？ 答案是： 没有直接可用的方法 。 虽然 Java 提供了： CharsetEncoder ByteBuffer String.getBytes() 但都需要手动处理，且实现复杂，不适合直接使用。 --- 错误实现方式（常见坑） ❌ 方式1：substring value.substring(0, 50); 问题：可能超过字节限制 ❌ 方式2：直接截断 byte[] new String(bytes, 0, maxBytes, UTF_8); 问题： 可能截断多字节字符 产生乱码（�） --- 正确实现：UTF-8安全按字节截断 public static String truncateUtf8(String value, int maxBytes) { if (value == null) return null; byte[] bytes = value.getBytes(StandardCharsets.UTF_8); if (bytes.length <= maxBytes) return value; int len = maxBytes; // 找到字符起点 int star...
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