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Those commonly used tool classes and methods in hutool
2022-07-06 11:43:00 【Ride the wind to break the bug】
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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();
}
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