Introduction to Hutool: A Comprehensive Java Utility Library

Hutool is a Java utility library that aggregates frequently used tools to simplify development, reduce repetitive code, and improve efficiency across various domains such as file I/O, encryption, caching, and more.

Features

tool-aop: JDK dynamic proxy wrapper for AOP without IoC.

hutool-bloomFilter: Bloom filter implementations with several hash algorithms.

hutool-cache: Caching utilities.

hutool-core: Core utilities including Bean operations, dates, and general helpers.

hutool-cron: Cron-like scheduled task module.

hutool-crypto: Encryption and decryption utilities.

hutool-db: JDBC wrapper based on ActiveRecord concepts.

hutool-dfa: Multi-keyword search using DFA models.

hutool-extra: Extensions for third‑party integrations (template engines, mail, etc.).

hutool-http: Http client built on HttpUrlConnection.

hutool-log: Automatic log facade detection.

hutool-script: Script execution wrapper (e.g., JavaScript).

hutool-setting: Enhanced configuration file and Properties handling.

hutool-system: System parameter access (JVM info, etc.).

hutool-json: JSON utilities.

hutool-captcha: Image captcha implementation.

Installation

<dependency>
    <groupId>cn.hutool</groupId>
    <artifactId>hutool-all</artifactId>
    <version>4.6.3</version>
</dependency>

Simple Tests

DateUtil – Demonstrates date conversion, formatting, and arithmetic.

//Date、long、Calendar之间的相互转换
//当前时间
Date date = DateUtil.date();
//Calendar转Date
date = DateUtil.date(Calendar.getInstance());
//时间戳转Date
date = DateUtil.date(System.currentTimeMillis());
//自动识别格式转换
String dateStr = "2017-03-01";
date = DateUtil.parse(dateStr);
//自定义格式化转换
date = DateUtil.parse(dateStr, "yyyy-MM-dd");
//格式化输出日期
String format = DateUtil.format(date, "yyyy-MM-dd");
int year = DateUtil.year(date);
int month = DateUtil.month(date);
Date beginOfDay = DateUtil.beginOfDay(date);
Date endOfDay = DateUtil.endOfDay(date);
Date newDate = DateUtil.offset(date, DateField.DAY_OF_MONTH, 2);
long betweenDay = DateUtil.between(date, newDate, DateUnit.DAY);

StrUtil – Shows string emptiness checks, prefix/suffix removal, and formatting.

String str = "test";
StrUtil.isEmpty(str);
StrUtil.isNotEmpty(str);
StrUtil.removeSuffix("a.jpg", ".jpg");
StrUtil.removePrefix("a.jpg", "a.");
String template = "这只是个占位符:{}";
String str2 = StrUtil.format(template, "我是占位符");
LOGGER.info("/strUtil format:{}", str2);

NumberUtil – Provides arithmetic operations, rounding, and type checks.

double n1 = 1.234;
double n2 = 1.234;
double result;
result = NumberUtil.add(n1, n2);
result = NumberUtil.sub(n1, n2);
result = NumberUtil.mul(n1, n2);
result = NumberUtil.div(n1, n2);
BigDecimal roundNum = NumberUtil.round(n1, 2);
String n3 = "1.234";
NumberUtil.isNumber(n3);
NumberUtil.isInteger(n3);
NumberUtil.isDouble(n3);

MapUtil – Illustrates map creation and emptiness checks.

Map
map = MapUtil.of(new String[][]{
    {"key1", "value1"},
    {"key2", "value2"},
    {"key3", "value3"}
});
MapUtil.isEmpty(map);
MapUtil.isNotEmpty(map);

SecureUtil – Demonstrates MD5 hashing.

String str = "123456";
String md5Str = SecureUtil.md5(str);
LOGGER.info("secureUtil md5:{}", md5Str);

CaptchaUtil – Shows how to generate and serve a line captcha image.

LineCaptcha lineCaptcha = CaptchaUtil.createLineCaptcha(200, 100);
try {
    request.getSession().setAttribute("CAPTCHA_KEY", lineCaptcha.getCode());
    response.setContentType("image/png");
    response.setHeader("Pragma", "No-cache");
    response.setHeader("Cache-Control", "no-cache");
    response.setDateHeader("Expire", 0);
    lineCaptcha.write(response.getOutputStream());
} catch (IOException e) {
    e.printStackTrace();
}

For more utilities and detailed documentation, visit the official Hutool website at https://www.hutool.cn/ and additional resources at https://www.yoodb.com/ . Using Hutool can significantly boost development productivity.