DateTimeFormatter

介绍

与传统的 SimpleDateFormat 相比，DateTimeFormat 是线程安全的

创建对象

public class DateTimeFormatTest {
    public static void main(String[] args) {
        DateTimeFormatter pattern = DateTimeFormatter.ofPattern("yyyy-mm-dd hh:mm:ss");
    }
}

格式化

import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;

public class DateTimeFormatTest {

    public static void main(String[] args) {
        DateTimeFormatter pattern = DateTimeFormatter.ofPattern("yyyy-mm-dd hh:mm:ss");
        String format = pattern.format(LocalDateTime.now());

        System.out.println(format);
    }
}

格式化方式2

import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;

public class DateTimeFormatTest {

    public static void main(String[] args) {
        DateTimeFormatter pattern = DateTimeFormatter.ofPattern("yyyy-mm-dd hh:mm:ss");

        LocalDateTime now = LocalDateTime.now();
        String s = now.format(pattern);

        System.out.println(s);
    }
}

将字符串解析成LocalDateTime

public class DateTimeFormatTest {

    public static void main(String[] args) {
        //注意 这里不用 HH 24小时的 下面解析是会报错的
        DateTimeFormatter pattern = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");

        LocalDateTime now = LocalDateTime.now();
        String s = now.format(pattern);

        System.out.println(s);


        LocalDateTime parse = LocalDateTime.parse(s, pattern);
        System.out.println(parse);

    }
}