[JAVA] I want to INSERT Spring Local Time with MySQL Time (also milliseconds)

Overview

`` `11: 12: 13.14``` (hours: minutes: seconds.milliseconds) obtained as a String type INSERT into MySQL And how to display up to milliseconds. (No date information required)

*** Isn't it possible to implement it normally? *** *** Do you think

It didn't work unless it seemed easy and had troublesome processing. .. .. If anyone knows a smarter way, I would be very happy if you could tell me! !!

version

Spring

build.gradle

id 'org.springframework.boot' version '2.2.2.BUILD-SNAPSHOT'
sourceCompatibility = '1.8'

	runtimeOnly('mysql:mysql-connector-java')
	implementation 'org.springframework.boot:spring-boot-starter'
	implementation('org.springframework.boot:spring-boot-starter-web')
	implementation('org.springframework.boot:spring-boot-starter-data-jpa')

Database

MySQL 8.0

Step 1 Create a table

Supports up to 3 decimal places MySQL :: MySQL 5.6 Reference Manual :: 11.1.2 Date and Time Type Overview

create table timesample( 
    ...
    start_time TIME(3)
);

Step 2 Create Attribute Converter

Since JPA does not support java.time.LocalDate, java.time.LocalTime, java.time.LocalDateTime as the field types of entities, you need to create the following AttributeConverter.

package app.entities.converter;

import java.time.LocalTime;

import javax.persistence.AttributeConverter;
import javax.persistence.Converter;

@Converter(autoApply = true)
public class LocalTimeConverter implements AttributeConverter<LocalTime,  java.sql.Time> {

    @Override
    public java.sql.Time convertToDatabaseColumn(LocalTime time) {
    	return time == null ? null : java.sql.Time.valueOf(time);
    }

    @Override
    public LocalTime convertToEntityAttribute(java.sql.Time  value) {
    	return value == null ? null : value.toLocalTime();
    }
}

Entity

	@Column(name = "start_time")
	private LocalTime startTime;

entity.setStartTime(LocalTime.of(11, 12, 13, 14*10000000));

repository.save(entity);

There are no milliseconds!

Step 3 Hold millisecond and convert to java.sql.Time

Change the convertToDatabaseColumn method of the LocalTimeConverter created earlier [How to map spring-millisecond java.time.LocalTime to millisecond java.sql.Time](https://stackoverflow.com/questions/51182366/how-to-map-java-time-localtime- with-milliseconds-to-a-java-sql-time-with-milisec)

LocalTimeConverter

package app.entities.converter;

import java.text.SimpleDateFormat;
import java.time.LocalDate;
import java.time.LocalTime;

import javax.persistence.AttributeConverter;
import javax.persistence.Converter;

@Converter(autoApply = true)
public class LocalTimeConverter implements AttributeConverter<LocalTime,  java.sql.Time> {

    @Override
    public java.sql.Time convertToDatabaseColumn(LocalTime time) {
    	if(time == null) return null;
    	
    	//This date will be discarded by conversion, so anything is OK
		long epochMilli = time.atDate(LocalDate.of(2019, 1, 1)).atZone(java.time.ZoneId.systemDefault())
				.toInstant().toEpochMilli();
		java.sql.Time sqlTime = new java.sql.Time(epochMilli);
    	return sqlTime;
    }

    @Override
    public LocalTime convertToEntityAttribute(java.sql.Time  value) {
    	if (value == null) return null;
    	
    	String localTimeStr = new SimpleDateFormat("HH:mm:ss.SSS").format(value);
    	LocalTime localTime = LocalTime.parse(localTimeStr);
    	return localTime;
    }
}