Boost Java Projects with Hutool: Essential Utility Library Overview

Today we recommend a very useful Java utility library, Hutool, which provides many enterprise‑level common utilities, helping avoid reinventing the wheel and saving development time.

Hutool (pronounced “hu‑tu”) aims for a carefree approach to coding.

Hutool is a Java toolkit that simplifies code by offering a wide range of utilities such as file I/O, streams, encryption/decryption, encoding, regular expressions, threading, XML handling, and more.

Official website: https://www.hutool.cn/

1. Features

Hutool wraps many JDK methods for files, streams, encryption, encoding, regex, threading, XML, etc., and provides the following components:

tool-aop – JDK dynamic proxy wrapper, offering AOP support without IoC.

hutool-bloomFilter – Bloom filter with various hash algorithms.

hutool-cache – Caching utilities.

hutool-core – Core utilities including bean operations, dates, 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 based on DFA model.

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

hutool-http – Http client built on HttpUrlConnection.

hutool-log – Log facade that auto‑detects the underlying implementation.

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

hutool-setting – Advanced configuration file and Properties handling.

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

hutool-json – JSON utilities.

hutool-captcha – Image captcha implementation.

2. Installation

Add the following dependency to your Maven pom.xml:

<dependency>
    <groupId>cn.hutool</groupId>
    <artifactId>hutool-all</artifactId>
    <version>5.8.23</version>
</dependency>

3. Simple Tests

DateUtil – Date and time utilities.

// Convert between Date, long, Calendar
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 parsing
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);
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.

// Check emptiness
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 = "This is a placeholder:{}";
String result = StrUtil.format(template, "I am the placeholder");
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 conversion and copying.

PmsBrand brand = new PmsBrand();
brand.setId(1L);
brand.setName("Xiaomi");
brand.setShowStatus(0);
Map<String, Object> 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);
BeanUtil.copyProperties(brand, copyBrand);
LOGGER.info("beanUtil copy properties:{}", copyBrand);

MapUtil – Map creation and checks.

Map<Object, Object> 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 image captcha.

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 Hutool utilities, refer to the official site: https://www.hutool.cn/