工具类Dateutil

import java.text.SimpleDateFormat;
import java.util.Date;

public class DateUtil {

    private DateUtil(){}

    public static String formatDate(Long timestamp){
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy年MM月dd日 HH时mm分ss秒");
        Date date = new Date(timestamp);
        return sdf.format(date);
    }
}

直接调用工具类

public class Test1 {
    public static void main(String[] args) {
        System.out.println(DateUtil.formatDate(System.currentTimeMillis()));
    }
}