Introducing Hutool: A Comprehensive Java Utility Library

Hutool (pronounced “hu‑tu”) is a Java utility library that aggregates a wide range of common functions—file I/O, encryption/decryption, date handling, regular expressions, threading, XML processing, and more—into convenient utility classes, helping developers avoid reinventing the wheel and speeding up development.

1. Features

to‑aop: JDK dynamic proxy wrapper providing AOP support without an IoC container.

hutool‑bloomFilter: Bloom filter implementation with various hash algorithms.

hutool‑cache: Caching utilities.

hutool‑core: Core utilities including Bean operations, date handling, and general helpers.

hutool‑cron: Cron‑like scheduling module.

hutool‑crypto: Encryption and decryption utilities.

hutool‑db: JDBC wrapper based on ActiveRecord concepts.

hutool‑dfa: Multi‑keyword search using DFA model.

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

hutool‑http: HttpUrlConnection‑based HTTP client.

hutool‑log: Automatic detection of logging implementations.

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

hutool‑setting: Enhanced configuration file and Properties handling.

hutool‑system: System parameter utilities (JVM info, etc.).

hutool‑json: JSON processing utilities.

hutool‑captcha: Image captcha generation.

2. Installation

Add the following dependency to your Maven pom.xml :

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

3. Simple Tests

DateUtil – common date‑time operations:

// Date, long, Calendar conversion
Date date = DateUtil.date(); // current time
date = DateUtil.date(Calendar.getInstance()); // Calendar to Date
date = DateUtil.date(System.currentTimeMillis()); // timestamp to Date
String dateStr = "2017-03-01";
date = DateUtil.parse(dateStr); // auto format detection
date = DateUtil.parse(dateStr, "yyyy-MM-dd"); // custom format
String format = DateUtil.format(date, "yyyy-MM-dd");
int year = DateUtil.year(date);
int month = DateUtil.month(date); // 0‑based
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 – string utilities:

// Empty check
String str = "test";
StrUtil.isEmpty(str);
StrUtil.isNotEmpty(str);
// Remove suffix/prefix
StrUtil.removeSuffix("a.jpg", ".jpg");
StrUtil.removePrefix("a.jpg", "a.");
// Format string
String template = "这只是个占位符:{}";
String result = StrUtil.format(template, "我是占位符");
LOGGER.info("/strUtil format:{}", result);

NumberUtil – numeric operations:

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);

BeanUtil – JavaBean ↔ Map conversion and property copying:

PmsBrand brand = new PmsBrand();
brand.setId(1L);
brand.setName("小米");
brand.setShowStatus(0);
Map
map = BeanUtil.beanToMap(brand);
LOGGER.info("beanUtil bean to map:{}", map);
PmsBrand mapBrand = BeanUtil.mapToBean(map, PmsBrand.class, false);
LOGGER.info("beanUtil map to bean:{}", mapBrand);
PmsBrand copyBrand = new PmsBrand();
BeanUtil.copyProperties(brand, copyBrand);
LOGGER.info("beanUtil copy properties:{}", copyBrand);

MapUtil – map creation and emptiness checks:

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

SecureUtil – MD5 hashing:

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

CaptchaUtil – generate 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();
}

Hutool provides many additional utilities; exploring its official website (https://www.hutool.cn/) can reveal further helpful methods that significantly improve development efficiency.