java时间模块

获取当前时间戳java

public class Demo1 {
    public static void main(String[] args) {
        // 获取当前时间戳
        long timestamp = System.currentTimeMillis();
        System.out.println(timestamp); // （单位毫秒） 1583847471988
    }
}

获取当前时间spa

import java.util.Date;

public class Demo1 {
    public static void main(String[] args) {
        // 获取当前时间
        Date date = new Date();
        System.out.println(date); // Tue Mar 10 21:38:58 CST 2020
    }
}

获取当前格式化时间code

import java.util.Date;
import java.text.SimpleDateFormat;
public class Demo1 {
    public static void main(String[] args) {
        // 获取当前时间
        Date date = new Date();
        System.out.println(date); // Tue Mar 10 21:38:58 CST 2020
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        String format_time =  sdf.format(date);
        System.out.println(format_time);  // 2020-03-10 21:41:00
    }
}

根据时间戳格式化当前时间orm

import java.util.Date;
import java.text.SimpleDateFormat;
public class Demo1 {
    public static void main(String[] args) {
        long timeStamp = 1583847471009L;
        SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        String sd0 = sdf.format(timeStamp);
        System.out.println(sd0); // 2020-03-10 21:37:51
        String sd2 = sdf.format(new Date(timeStamp));
        System.out.println(sd2); // 2020-03-10 21:37:51
    }
}

格式化时间转成时间戳get

import java.text.ParseException;
import java.util.Date;
import java.text.SimpleDateFormat;
public class Demo1 {
    // 抛出一个解析异常类
    public static void main(String[] args) throws ParseException {
        String format_time = "2020-03-10 21:37:51";
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        Date struct_time = sdf.parse(format_time);
        long timestamp = struct_time.getTime();
        System.out.println(timestamp); //
    }
}

一周以前的时间io

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

public class Demo1 {
    public static void main(String[] args) {
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(new Date());
        calendar.add(Calendar.DATE,-7);
      	// 一月以前的时间
      	// calendar.add(Calendar.MONTH,-1);
      	// 一年前
        // calendar.add(Calendar.YEAR,-1);
        Date day = calendar.getTime();
        String before7Days = sdf.format(day);
        System.out.println(before7Days);
    }
}

一周以后的时间form

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

public class Demo1 {
    public static void main(String[] args) {
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(new Date());
        calendar.add(Calendar.DATE,7);
        // 一月以后的时间
      	// calendar.add(Calendar.MONTH,1);
      	// 一年后
        // calendar.add(Calendar.YEAR,1);
        Date day = calendar.getTime();
        String before7Days = sdf.format(day);
        System.out.println(before7Days);
    }
}