java中Date、 LocalDate、String互相转换

引入相关Package

import java.text.SimpleDateFormat;
import java.time.Instant;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.LocalTime;
import java.time.ZoneId;
import java.time.ZonedDateTime;
import java.time.format.DateTimeFormatter;
import java.util.Date;

import com.example.base;

LocalDate 与 String 之间的互转

    DateTimeFormatter fmt1 = DateTimeFormatter.ofPattern("yyyy-MM-dd");
    LocalDate localDate = LocalDate.now();
    String dateStr = localDate.format(fmt1);
    System.out.println(dateStr);

    String date1 = "2023-08-30";
    LocalDate localDate1 = LocalDate.parse(date1, fmt1);
    System.out.println(localDate1);

LocalTime 与 String 之间的互转

    DateTimeFormatter fmt2 = DateTimeFormatter.ofPattern("HH:mm:ss");
    LocalTime localTime1 = LocalTime.now();
    LocalTime localTime2 = LocalTime.parse("12:30:30");
    LocalTime localTime3 = LocalTime.parse("12:30:30", DateTimeFormatter.ofPattern("HH:mm:ss"));
    System.out.println(localTime1.format(fmt2));
    System.out.println(localTime2.format(fmt2));
    System.out.println(localTime3.format(fmt2));

    String localTime = "10:30:30";
    LocalTime localTime4 = LocalTime.parse(localTime, fmt2);
    System.out.println(localTime4);

LocalDateTime 与 String 之间的互转

    DateTimeFormatter fmt3 = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
    LocalDateTime ldt1 = LocalDateTime.parse("2019-12-07 21:20:06", fmt3);
    LocalDateTime ldt2 = LocalDateTime.now();
    System.out.println(fmt3.format(ldt1));
    System.out.println(fmt3.format(ldt2));

    String localDateTime_Str = "2023-12-07 21:20:06";
    LocalDateTime ldt3 = LocalDateTime.parse(localDateTime_Str, fmt3);
    System.out.println(ldt3);

Date与 LocalDate,LocalTime, LocalDateTime 互转

    Date date = new Date();
    ZoneId zoneId = ZoneId.systemDefault();
    ZonedDateTime zonedDateTime = date.toInstant().atZone(zoneId);
    LocalDateTime ldtime = zonedDateTime.toLocalDateTime();
    //或者 LocalDateTime localDateTimex =
    // LocalDateTime.ofInstant(date.toInstant(),zoneId);
    LocalDate ld1 = zonedDateTime.toLocalDate();
    LocalTime lt1 = zonedDateTime.toLocalTime();

    System.out.println(ldtime);
    System.out.println(ld1);
    System.out.println(lt1);

LocalDate,LocalTime, LocalDateTime与Date互转

    LocalDate lcd = LocalDate.now();
    ZoneId zone = ZoneId.systemDefault();
    Instant instant = lcd.atStartOfDay().atZone(zone).toInstant();
    Date datefirst = Date.from(instant);

    LocalTime localTime_1 = LocalTime.now();
    LocalDate localDate_1 = LocalDate.now();
    LocalDateTime localDateTime = LocalDateTime.of(localDate_1, localTime_1);
    Instant inst = localDateTime.atZone(zone).toInstant();
    Date dateSecond = Date.from(inst);

    LocalDateTime localDateTime_1 = LocalDateTime.now();
    ZoneId zoneId_1 = ZoneId.systemDefault();
    Instant instant_1 = localDateTime_1.atZone(zoneId_1).toInstant();
    Date dateThird = Date.from(instant_1);

    SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
    System.out.println(dateFormat.format(datefirst));
    System.out.println(dateFormat.format(dateSecond));
    System.out.println(dateFormat.format(dateThird));