Introducing Hutool: A Comprehensive Java Utility Library and Its Usage

The author, Ryan Wang, recommends the Hutool Java utility library, a comprehensive collection of tools that simplify everyday coding tasks, reduce boilerplate, and help developers avoid reinventing the wheel.

Key Modules

hutool-aop – JDK dynamic proxy wrapper providing AOP support without IoC.

hutool-bloomFilter – Bloom filter implementation with various hash algorithms.

hutool-cache – Caching utilities.

hutool-core – Core utilities including Bean operations, date handling, and common 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 based on DFA model.

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

hutool-http – Http client built on HttpUrlConnection.

hutool-log – Automatic detection of logging implementations.

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

hutool-setting – Advanced configuration file and Properties handling.

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

hutool-json – JSON handling utilities.

hutool-captcha – Image captcha generation utilities.

Installation

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

Simple Usage Examples

DateUtil – common date‑time operations:

// Date, long, Calendar conversion
Date date = DateUtil.date();
date = DateUtil.date(Calendar.getInstance());
date = DateUtil.date(System.currentTimeMillis());
String dateStr = "2017-03-01";
date = DateUtil.parse(dateStr);
date = DateUtil.parse(dateStr, "yyyy-MM-dd");
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:

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 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);
NumberUtil.isNumber("1.234");
NumberUtil.isInteger("123");
NumberUtil.isDouble("1.234");

MapUtil – map creation and 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 – generating image captchas:

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();
}

Overall, Hutool provides a rich set of ready‑to‑use utilities that can greatly improve Java development productivity; readers are encouraged to visit the official website for more modules and examples.