java 日期类型的转换-JZTXT

封装的工具类，主要用于LocalDateTime、Date、String 三者之间的相互转换。其中String与Date的转换还可以使用SimpleDateFormat，这里主要以DateTimeFormatter为主。

import java.text.SimpleDateFormat;
import java.time.LocalDateTime;
import java.time.OffsetDateTime;
import java.time.ZoneId;
import java.time.ZoneOffset;
import java.time.format.DateTimeFormatter;
import java.time.temporal.TemporalAccessor;
import java.util.Date;


public class DateUtil {
    public static final String DATE_FORMAT = "yyyy-MM-dd HH:mm:ss";


    /**
     * String 转 LocalDateTime
     * @param date
     * @return
     */
    public static LocalDateTime stringToLocalDateTime(String date) {

        //也可以自己定义格式
        //DateTimeFormatter formatter = DateTimeFormatter.ISO_OFFSET_DATE_TIME;
        DateTimeFormatter formatter = DateTimeFormatter.ISO_LOCAL_DATE_TIME;
        LocalDateTime dateTime = LocalDateTime.parse(date, formatter);

        return dateTime;

    }

    /**
     * localDateTime 转 时间戳
     * @param localDateTime
     * @return
     */

    public static Long localDateTimeToTimeStamp(LocalDateTime localDateTime) {
        return localDateTime.toInstant(ZoneOffset.of("+8")).toEpochMilli();
    }

    /**
     * String 转 Date
     * @param happenTime
     * @param dateFormat
     * @return
     */
    public static Date stringToDate(String happenTime, String dateFormat) {

        DateTimeFormatter formatter = DateTimeFormatter.ofPattern(dateFormat);
        OffsetDateTime offsetDateTime = OffsetDateTime.parse(happenTime, formatter);

        // 转换为java.util.Date对象
        Date date = Date.from(offsetDateTime.toInstant());

        return date;
    }



    /**
     * Date 转字符串 用SimpleDateFormat
     *
     * @param time
     * @return
     */
    public static String format(Date time) {
        return format(time, DATE_FORMAT);
    }

    public static String format(Date time, String pattern) {
        SimpleDateFormat formatter = new SimpleDateFormat(pattern);
        return formatter.format(time);
    }


    /**
     * Date 转字符串  用DateTimeFormatter
     */

    public static String format2(Date time, String pattern) {
        DateTimeFormatter formatter = DateTimeFormatter.ofPattern(pattern);
        return formatter.format(date2LocalDateTime(time));
    }


    /**
     * LocalDateTime 转字符串
     */
    public static String format3(LocalDateTime time, String pattern) {
        DateTimeFormatter formatter = DateTimeFormatter.ofPattern(pattern);
        return formatter.format(time);

    }

    /**
     * Date 转 LocalDateTime
     */
    public static LocalDateTime date2LocalDateTime(Date date) {
        return date.toInstant().atZone(ZoneId.systemDefault()).toLocalDateTime();
    }

    /**
     * LocalDateTime 转Date
     */
    public static Date localDateTime2Date(LocalDateTime time) {
        return Date.from(time.atZone(ZoneId.systemDefault()).toInstant());
    }
}

两个实体类，主要涉及对象与json串之间的转换（涉及日期类型），当对象含有LocalDateTime、LocalDate、LocalTime类型的属性时，在利用ObjectMapper转换成Json字符串时，需要给objectMapper添加一些格式类型。

package com.example.restservice.pojo;

import com.fasterxml.jackson.annotation.JsonFormat;
import com.fasterxml.jackson.annotation.JsonProperty;
import lombok.AllArgsConstructor;
import lombok.Builder;
import lombok.Data;
import lombok.NoArgsConstructor;
import org.springframework.format.annotation.DateTimeFormat;

import java.util.Date;

@Data
@Builder
@AllArgsConstructor
@NoArgsConstructor
public class Animal {
    private String name;
    private Integer age;
   @JsonFormat(pattern = "yyyy-MM-dd'T'HH:mm:ss", timezone = "GMT+8")
    private Date birthday;
}

package com.example.restservice.pojo;

import com.fasterxml.jackson.annotation.JsonFormat;
import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
import com.fasterxml.jackson.databind.annotation.JsonSerialize;
import com.fasterxml.jackson.datatype.jsr310.deser.LocalDateDeserializer;
import com.fasterxml.jackson.datatype.jsr310.ser.LocalDateSerializer;
import lombok.AllArgsConstructor;
import lombok.Builder;
import lombok.Data;
import lombok.NoArgsConstructor;

import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.LocalTime;
import java.util.Date;
@Data
@Builder
@AllArgsConstructor
@NoArgsConstructor
public class AnimalCC {
    private String name;
    private Integer age;

    @JsonFormat(pattern = "yyyy-MM-dd'T'HH:mm:ss", timezone = "GMT+8")
    private LocalDateTime birthday;

    private LocalDate localDate;
    @JsonFormat(pattern = "HH:mm:ss:SSS", timezone = "GMT+8")
    private LocalTime localTime;
}

一些测试例子

package com.example.restservice.util;

import com.example.restservice.pojo.Animal;
import com.example.restservice.pojo.AnimalCC;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.datatype.jsr310.*;
import com.fasterxml.jackson.datatype.jsr310.ser.LocalDateSerializer;
import com.fasterxml.jackson.datatype.jsr310.ser.LocalDateTimeSerializer;
import com.fasterxml.jackson.datatype.jsr310.ser.LocalTimeSerializer;

import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.LocalTime;
import java.time.ZoneId;
import java.time.format.DateTimeFormatter;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;

public class Test {
    public static void main(String[] args) throws JsonProcessingException, ParseException {


        ObjectMapper objectMapper = new ObjectMapper();
        JavaTimeModule javaTimeModule = new JavaTimeModule();
        javaTimeModule.addSerializer(LocalDateTime.class, new LocalDateTimeSerializer(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss")));
        javaTimeModule.addSerializer(LocalDate.class, new LocalDateSerializer(DateTimeFormatter.ofPattern("yyyy-MM-dd")));
        javaTimeModule.addSerializer(LocalTime.class, new LocalTimeSerializer(DateTimeFormatter.ofPattern("HH:mm:ss")));
        objectMapper.registerModule(javaTimeModule);

        Animal animal = new Animal();
        animal.setAge(3);
        animal.setName("小狗");
        animal.setBirthday(new Date());
        System.out.println(animal);
        String s = objectMapper.writeValueAsString(animal);
        System.out.println(s);
        System.out.println("=====================================");
        System.out.println(animal.getBirthday());
        DateTimeFormatter dateTimeFormatter = DateTimeFormatter.ofPattern("yyyy/MM/dd-HH:mm:ss.SSS");
        System.out.println(dateTimeFormatter.format(LocalDateTime.now()));


        String dateTime1 = "2021-01-01T12:12:12.123+08:00";
        SimpleDateFormat simpleDateFormat2 = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSS+08:00");
        Animal animal1 = new Animal();
        animal1.setAge(3);
        animal1.setName("小狗");
        animal1.setBirthday(simpleDateFormat2.parse(dateTime1));
        System.out.println(simpleDateFormat2.format(new Date()));
        System.out.println(animal);
        String s8 = objectMapper.writeValueAsString(animal);
        System.out.println(s8);


        System.out.println("=====================================");


        AnimalCC animalCC = new AnimalCC();
        animalCC.setAge(3);
        animalCC.setName("小狗");
        animalCC.setBirthday(DateUtil.date2LocalDateTime(new Date()));
        animalCC.setLocalDate(LocalDateTime.now().toLocalDate());
        animalCC.setLocalTime(LocalDateTime.now().toLocalTime());
        System.out.println(animalCC);
        String s2 = objectMapper.writeValueAsString(animalCC);
        System.out.println(s2);


        System.out.println("=====================================");
        String dateTime = "2021-01-01T12:12:12";
        SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss");
        Date date = simpleDateFormat.parse(dateTime);
        String s3 = simpleDateFormat.format(date);
        System.out.println(date);
        System.out.println(s3);
        String s1 = objectMapper.writeValueAsString(date);
        System.out.println(s1);


        Date from = Date.from(DateUtil.stringToLocalDateTime(dateTime).atZone(ZoneId.systemDefault()).toInstant());
        System.out.println(from);
        LocalDateTime localDateTime = DateUtil.stringToLocalDateTime(dateTime);
        System.out.println(localDateTime);


        System.out.println("**********************************************");
        System.out.println(DateUtil.format3(LocalDateTime.now(), "yyyy-MM-dd HH:mm:ss"));
        System.out.println(DateUtil.format2(new Date(), "yyyy-MM-dd HH:mm:ss.SSS+08:00"));


        System.out.println("**********************************************");
        String animalStr = "{\"name\":\"小狗\",\"age\":3,\"birthday\":\"2021-01-01T12:12:12\"}";
        String animalStr2 = "{\"name\":\"小狗\",\"age\":3,\"birthday\":\"2021-01-01T12:12:12\",\"localDate\":\"2021-01-01\",\"localTime\":\"12:12:12.333\"}";
        Animal animal2 = objectMapper.readValue(animalStr, Animal.class);
        AnimalCC animalCC2 = objectMapper.readValue(animalStr2, AnimalCC.class);
        System.out.println(animal2);
        System.out.println(animalCC2);


    }
}