常用工具类-commons-lang3
1.依赖
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-lang3</artifactId>
<version>3.9</version>
</dependency>
2.字符串-StringUtils
public static void stringUtils() {
String s1 = "hello world";
// 缩写，将多余的部分替换为 ...
String abbreviate = StringUtils.abbreviate(s1, 6);
System.out.println(abbreviate); // hel...
// 第一个字母大写
String capitalize = StringUtils.capitalize(s1);
System.out.println(capitalize);
// 追加，以2结尾返回，原字符串；不以2结尾，在h1后面追加2
String appendIfMissing1 = StringUtils.appendIfMissing("h1", "2");
System.out.println(appendIfMissing1); //h12
// 替换字符串的中间部分
String abbreviateMiddle = StringUtils.abbreviateMiddle("15829551111", "****", 10);
System.out.println(abbreviateMiddle); // 158****111
// 扩展字符串
String center = StringUtils.center("12", 6, "k");
System.out.println(center); // kk12kk
// 去掉 \r 转义字符
String chomp = StringUtils.chomp("123\r");
System.out.println(chomp); // 123
// null -> ""
String defaultString = StringUtils.defaultString(null);
System.out.println(defaultString); // ""
String chop = StringUtils.chop("123");
System.out.println(chop); // 12
System.out.println("=============");
// 第二个字符串和第一的不同，从第一字符串索引为1开始比较
String difference = StringUtils.difference("12345", "15678");
System.out.println(difference); // 5678
// 获取数字
String digits = StringUtils.getDigits("a1d23");
System.out.println(digits); // 123
boolean blank = StringUtils.isBlank(" ");
System.out.println(blank); // true
boolean empty = StringUtils.isEmpty(" ");
System.out.println(empty); // false
// 是字符
boolean alpha = StringUtils.isAlpha("adf)");
System.out.println(alpha); // false
// 只有字母和数字
boolean alphanumeric = StringUtils.isAlphanumeric("abc");
System.out.println(alphanumeric); // true
// 是否是大小写混合的
boolean mixedCase = StringUtils.isMixedCase("aBc");
System.out.println(mixedCase); // true
String format = String.format("12 %s 13 %s 14 %d", "a", "b", 1);
System.out.println(format);
}
3.日期-DateUtils
public class DateDemo {
public static void main(String[] args) {
//stringToDate();
//dateAdd();
//instantAndDateConvert();
//instantAdd();
//localDate();
//localTime();
localDateTime();
}
public static void localDateTime() {
LocalDateTime now = LocalDateTime.now();
System.out.println(now); // 2021-12-07T16:20:59.301
// 加10天
LocalDateTime _10 = now.plusDays(10);
System.out.println(_10); // 2021-12-17T16:20:59.301
// 时间比较
if (now.isBefore(_10)) { // true
System.out.println("now 在 _10 之前");
}
// 格式转换
String s1 = now.format(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss"));
System.out.println(s1); // 2021-12-07 16:20:59
String s2 = now.format(DateTimeFormatter.ISO_DATE_TIME);
System.out.println(s2); // 2021-12-07T16:20:59.301
// 转换
// LocalDateTime to Date
Instant instant = now.atZone(ZoneId.systemDefault()).toInstant();
Date date = Date.from(instant);
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
String format = sdf.format(date);
System.out.println(format); // 2021-12-07 16:20:59
// Date To LocalDateTime
Date nowDate = new Date();
LocalDateTime localDateTime = LocalDateTime.ofInstant(nowDate.toInstant(), ZoneId.systemDefault());
System.out.println(localDateTime); // 2021-12-07T16:20:59.329
}
public static void localTime() {
LocalTime now = LocalTime.now();
System.out.println(now); // 16:03:59.251
// 加10小时
LocalTime _10 = now.plusHours(10); // 02:03:59.251
System.out.println(_10);
}
public static void localDate() {
LocalDate now = LocalDate.now();
System.out.println(now); // 2021-12-07
System.out.println(now.lengthOfYear()); // 365
// 加10天
LocalDate _10 = now.plusDays(10);
// LocalData使用final修改，不可变，操作之后会生成一个新对象
System.out.println(now); // 2021-12-07
System.out.println(_10); // 2021-12-17
// 格式化
String s1 = now.format(DateTimeFormatter.BASIC_ISO_DATE);
System.out.println(s1); // 20211207
String s2 = now.format(DateTimeFormatter.ofPattern("yyyy--MM--dd"));
System.out.println(s2); // 2021--12--07
}
public static void instantAdd() {
long second = 1000;
long minute = second * 60;
long hour = minute * 60;
long day = hour * 24;
System.out.println(new Date().getTime()); // 1638862868672 2021-12-07 15:41
Instant instant = Instant.ofEpochMilli(1638862868672L);
System.out.println(instant); // 2021-12-07T07:41:08.672Z
// 加一天
Instant millis = instant.plusMillis(day);
// Instant使用final修改，不可变，操作后会生成一个新对象
System.out.println(instant); // 2021-12-07T07:41:08.672Z
System.out.println(millis); // 2021-12-08T07:41:08.672Z
}
public static void instantAndDateConvert() {
// Instant to Date
Instant instant = Instant.now();
System.out.println(instant); // 2021-12-07T07:38:35.189Z
Date now = Date.from(instant); // 对时区进行自动转 +8小时
System.out.println(now); // Tue Dec 07 15:37:35 CST 2021
// Date to Instant
Instant toInstant = now.toInstant();
System.out.println(toInstant); // 2021-12-07T07:39:29.644Z
}
public static void dateAdd() {
long second = 1000;
long minute = second * 60;
long hour = minute * 60;
long day = hour * 24;
// 当前时间
Date now = new Date();
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
String format = sdf.format(now);
System.out.println(format); // 2021-12-07 15:24:37
// 通过加减毫秒数进行时间的加减
long nextDay = now.getTime() + day;
Date nextDate = new Date(nextDay);
System.out.println(sdf.format(nextDate)); // 2021-12-08 15:25:53
}
public static void stringToDate() {
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
String s = "2021-12-07 15:10:55";
Date date = null;
try {
date = sdf.parse(s);
} catch (ParseException e) {
e.printStackTrace();
}
}
public static void dateToString() {
Date date = new Date();
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
String format = sdf.format(date);
System.out.println(format);
}
}
4.反射
- 获取注解中的值。
public static void getAnnotation() throws Exception {
Field[] declaredFields = User.class.getDeclaredFields();
for (Field field : declaredFields) {
String name = field.getName();
Value annotation = field.getAnnotation(Value.class);
String value = annotation.value();
System.out.println("name" + name + " - " + value);
}
}
- 反射-缺省
public static void introspector(Apple apple) {
try {
BeanInfo beanInfo = Introspector.getBeanInfo(apple.getClass());
PropertyDescriptor[] propertyDescriptors = beanInfo.getPropertyDescriptors();
for (PropertyDescriptor propertyDescriptor : propertyDescriptors) {
// 属性名
String fieldName = propertyDescriptor.getName();
if (fieldName.endsWith("Name")) {
Method readMethod = propertyDescriptor.getReadMethod();
Object invoke = readMethod.invoke(apple);
if (invoke instanceof Integer) {
Method writeMethod = propertyDescriptor.getWriteMethod();
writeMethod.invoke(apple, 10);
}
}
}
} catch (IntrospectionException | IllegalAccessException | InvocationTargetException e) {
e.printStackTrace();
}
}
5.Get和Post请求
/*
<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpmime</artifactId>
<version>4.5.3</version>
</dependency>
*/
public static String get() throws IOException, URISyntaxException {
String idCard = "123456xxx";
String beginTime = "2000-01-02 14:30:00";
String endTime = "2022-01-04 12:33:00";
String cookie = "JSESSIONID=123456xxx";
String urlPath = "https://localhost:8080/get/id/card/";
CloseableHttpClient client = HttpClients.createDefault();
String realUrl = urlPath + idCard + "?beginTime=" + beginTime + "&endTime=" + endTime;
// 使用URL对拼接的请求进行包装，否则由于Get请求时请求地址中有空格会出现异常。
// Caused by: java.net.URISyntaxException:
// Illegal character in query at index 65:
// https://localhost:8080/get/id/card/123456xxx?beginTime=2000-01-02 14:30:00&endTime=2022-01-04 12:33:00
URL url = new URL(realUrl);
URI uri = new URI(url.getProtocol(), url.getHost(), url.getPath(), url.getQuery(), null);
HttpGet httpGet = new HttpGet(uri);
httpGet.setHeader("Cookie", cookie);
try (CloseableHttpResponse response = client.execute(httpGet)) {
if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {
HttpEntity resEntity = response.getEntity();
return EntityUtils.toString(resEntity);
}
} catch (Exception e) {
log.info("e ", e);
}
return null;
}
7.发送请求-携带请求body
/*
<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>fluent-hc</artifactId>
<version>4.5.13</version>
</dependency>
*/
public static void post() {
// 请求URL
String url = "http://127.0.0.1:8080/user";
// 请求body
String body = "body";
try {
Content response = Request.Post(url).bodyByteArray(body.getBytes())
.execute().returnContent();
// 输出响应
System.out.println(response.toString());
} catch (IOException e) {
e.printStackTrace();
}
}
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