Those commonly used tool classes and methods in hutool

Convert

Type conversion utility class , For conversion of various types of data .

// Convert to string 
int a = 1;
String aStr = Convert.toStr(a);
// Convert to array of specified type 
String[] b = {"1", "2", "3", "4"};
Integer[] bArr = Convert.toIntArray(b);
// Convert to date object 
String dateStr = "2017-05-06";
Date date = Convert.toDate(dateStr);
// Convert to list 
String[] strArr = {"a", "b", "c", "d"};
List<String> strList = Convert.toList(String.class, strArr);

DateUtil

Date time tool class , Some commonly used date time operation methods are defined .

//Date、long、Calendar Mutual conversion between 
// current time 
Date date = DateUtil.date();
//Calendar turn Date
date = DateUtil.date(Calendar.getInstance());
// Time stamping Date
date = DateUtil.date(System.currentTimeMillis());
// Automatic recognition of format conversion 
String dateStr = "2017-03-01";
date = DateUtil.parse(dateStr);
// Custom format conversion 
date = DateUtil.parse(dateStr, "yyyy-MM-dd");
// Format output date 
String format = DateUtil.format(date, "yyyy-MM-dd");
// Get part of the year 
int year = DateUtil.year(date);
// Get the month , from 0 Start counting 
int month = DateUtil.month(date);
// Get the start of a day 、 End time 
Date beginOfDay = DateUtil.beginOfDay(date);
Date endOfDay = DateUtil.endOfDay(date);
// Calculate the date time after the offset 
Date newDate = DateUtil.offset(date, DateField.DAY_OF_MONTH, 2);
// Calculate the offset between date and time 
long betweenDay = DateUtil.between(date, newDate, DateUnit.DAY);

StrUtil

String utility class , Some common string manipulation methods are defined .

// Determine if it is an empty string 
String str = "test";
StrUtil.isEmpty(str);
StrUtil.isNotEmpty(str);
// Remove the prefixes and suffixes of strings 
StrUtil.removeSuffix("a.jpg", ".jpg");
StrUtil.removePrefix("a.jpg", "a.");
// Formatted string 
String template = " It's just a placeholder :{}";
String str2 = StrUtil.format(template, " I'm a placeholder ");
LOGGER.info("/strUtil format:{}", str2);

ClassPathResource

obtain classPath The files under the , stay Tomcat Wait for the container ,classPath It's usually WEB-INF/classes.

// Access is defined in src/main/resources Profile in folder 
ClassPathResource resource = new ClassPathResource("generator.properties");
Properties properties = new Properties();
properties.load(resource.getStream());
LOGGER.info("/classPath:{}", properties);

ReflectUtil

Java Reflection tools , It can be used to reflect the methods of getting classes and creating objects .

// Get all the methods of a class 
Method[] methods = ReflectUtil.getMethods(PmsBrand.class);
// Get the specified method of a class 
Method method = ReflectUtil.getMethod(PmsBrand.class, "getId");
// Use reflection to create objects 
PmsBrand pmsBrand = ReflectUtil.newInstance(PmsBrand.class);
// The method of reflecting the execution object 
ReflectUtil.invoke(pmsBrand, "setId", 1);

NumberUtil

Digital processing tools , It can be used for addition, subtraction, multiplication and division of various types of numbers and judgment types .

double n1 = 1.234;
double n2 = 1.234;
double result;
// Yes float、double、BigDecimal Do addition, subtraction, multiplication and division 
result = NumberUtil.add(n1, n2);
result = NumberUtil.sub(n1, n2);
result = NumberUtil.mul(n1, n2);
result = NumberUtil.div(n1, n2);
// Keep two decimal places 
BigDecimal roundNum = NumberUtil.round(n1, 2);
String n3 = "1.234";
// Judge whether it is a number 、 Integers 、 Floating point numbers 
NumberUtil.isNumber(n3);
NumberUtil.isInteger(n3);
NumberUtil.isDouble(n3);

BeanUtil

JavaBean Tool class of , Can be used for Map And JavaBean The mutual transformation of objects and the copy of object properties .

PmsBrand brand = new PmsBrand();
brand.setId(1L);
brand.setName(" millet ");
brand.setShowStatus(0);
//Bean turn Map
Map<String, Object> map = BeanUtil.beanToMap(brand);
LOGGER.info("beanUtil bean to map:{}", map);
//Map turn Bean
PmsBrand mapBrand = BeanUtil.mapToBean(map, PmsBrand.class, false);
LOGGER.info("beanUtil map to bean:{}", mapBrand);
//Bean Property copy 
PmsBrand copyBrand = new PmsBrand();
BeanUtil.copyProperties(brand, copyBrand);
LOGGER.info("beanUtil copy properties:{}", copyBrand);

CollUtil

Tool class for collection operation , Some common set operations are defined .

// Array to list 
String[] array = new String[]{"a", "b", "c", "d", "e"};
List<String> list = CollUtil.newArrayList(array);
//join： When the array is converted to a string, add the connection symbol 
String joinStr = CollUtil.join(list, ",");
LOGGER.info("collUtil join:{}", joinStr);
// Reconverts a string separated by a join symbol to a list 
List<String> splitList = StrUtil.split(joinStr, ',');
LOGGER.info("collUtil split:{}", splitList);
// Create a new Map、Set、List
HashMap<Object, Object> newMap = CollUtil.newHashMap();
HashSet<Object> newHashSet = CollUtil.newHashSet();
ArrayList<Object> newList = CollUtil.newArrayList();
// Determine whether the list is empty 
CollUtil.isEmpty(list);

MapUtil

Map Operation tool class , Can be used to create Map Object and judgment Map Is it empty .

// Add multiple key value pairs to Map in 
Map<Object, Object> map = MapUtil.of(new String[][]{
    {"key1", "value1"},
    {"key2", "value2"},
    {"key3", "value3"}
});
// Judge Map Is it empty 
MapUtil.isEmpty(map);
MapUtil.isNotEmpty(map);

AnnotationUtil

Annotation tool class , Can be used to get comments and values specified in comments .

// Get the specified class 、 Method 、 Field 、 List of annotations on the constructor 
Annotation[] annotationList = AnnotationUtil.getAnnotations(HutoolController.class, false);
LOGGER.info("annotationUtil annotations:{}", annotationList);
// Get the specified type annotation 
Api api = AnnotationUtil.getAnnotation(HutoolController.class, Api.class);
LOGGER.info("annotationUtil api value:{}", api.description());
// Gets the value of the specified type annotation 
Object annotationValue = AnnotationUtil.getAnnotationValue(HutoolController.class, RequestMapping.class);

SecureUtil

Encryption and decryption tool class , Can be used for MD5 encryption .

//MD5 encryption 
String str = "123456";
String md5Str = SecureUtil.md5(str);
LOGGER.info("secureUtil md5:{}", md5Str);

CaptchaUtil

Verification code tool class , Can be used to generate graphic verification codes .

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