Javaで現在のタイムスタンプを取得する方法
Javaで現在のタイムスタンプを取得するには：
Timestamp timestamp = new Timestamp(System.currentTimeMillis()); //2016-11-16 06:43:19.77
Javaで現在のタイムスタンプを取得する方法を示す2つのJavaの例を次に示します。 （Java 8で更新）
1. java.sql.Timestamp
現在のjava.sql.Timestampを取得する2つの方法
TimeStampExample.java
package com.example.date;
import java.sql.Timestamp;
import java.text.SimpleDateFormat;
import java.util.Date;
public class TimeStampExample {
private static final SimpleDateFormat sdf = new SimpleDateFormat("yyyy.MM.dd.HH.mm.ss");
public static void main(String[] args) {
//method 1
Timestamp timestamp = new Timestamp(System.currentTimeMillis());
System.out.println(timestamp);
//method 2 - via Date
Date date = new Date();
System.out.println(new Timestamp(date.getTime()));
//return number of milliseconds since January 1, 1970, 00:00:00 GMT
System.out.println(timestamp.getTime());
//format timestamp
System.out.println(sdf.format(timestamp));
}
}
出力
2016-11-16 06:43:19.77 2016-11-16 06:43:19.769 1479249799770 2016.11.16.06.43.19
2. java.time.Instant
Java 8では、java.sql.Timestampを新しいjava.time.Instantに変換できます。
InstantExample.java
package com.example.date;
import java.sql.Timestamp;
import java.time.Instant;
public class InstantExample {
public static void main(String[] args) {
Timestamp timestamp = new Timestamp(System.currentTimeMillis());
System.out.println(timestamp);
//return number of milliseconds since January 1, 1970, 00:00:00 GMT
System.out.println(timestamp.getTime());
// Convert timestamp to instant
Instant instant = timestamp.toInstant();
System.out.println(instant);
//return number of milliseconds since the epoch of 1970-01-01T00:00:00Z
System.out.println(instant.toEpochMilli());
// Convert instant to timestamp
Timestamp tsFromInstant = Timestamp.from(instant);
System.out.println(tsFromInstant.getTime());
}
}
出力
2016-11-16 06:55:40.11 1479250540110 2016-11-15T22:55:40.110Z 1479250540110 1479250540110