Java中Date、LocalDate、LocalDateTime、LocalTime、时间戳之间的相互转换代码

    @test
    public void test06(){
        simpledateformat sdf = new simpledateformat("yyyy-mm-dd hh:mm:ss");
        // date
        date date = new date();
        system.out.println("date\t" + sdf.format(date));

        // date 转 localdatetime
        datetimeformatter dtf = datetimeformatter.ofpattern("yyyy-mm-dd hh:mm:ss");
        localdatetime datetolocaldatetime = date.toinstant().atzone(zoneid.systemdefault()).tolocaldatetime();
        system.out.println("date to localdatetime\t" + dtf.format(datetolocaldatetime));
    }

    @test
    public void test07(){
        simpledateformat sdf = new simpledateformat("yyyy-mm-dd hh:mm:ss");
        // date
        date date = new date();
        system.out.println("date\t" + sdf.format(date));

        // date 转 localdate
        // 注意 localdate 只能有年月日，格式化日期不能有时分秒，否则会报错
        datetimeformatter dtf = datetimeformatter.ofpattern("yyyy-mm-dd");
        localdate datetolocaldate = date.toinstant().atzone(zoneid.systemdefault()).tolocaldate();
        system.out.println("date to localdate\t" + dtf.format(datetolocaldate));
    }

    @test
    public void test08(){
        // localdatetime 转 localdate
        datetimeformatter dtf = datetimeformatter.ofpattern("yyyy-mm-dd");
        localdate localdatetimetolocaldate = localdatetime.now().tolocaldate();
        system.out.println("localdatetime to localdate\t" + dtf.format(localdatetimetolocaldate));
    }

    @test
    public void test09(){
        // localdatetime 转 localtime
        // 注意 localtime 只能有时分秒，格式化日期不能有年月日，否则会报错
        datetimeformatter dtf = datetimeformatter.ofpattern("hh:mm:ss");
        localtime localdatetimetolocaltime = localdatetime.now().tolocaltime();
        system.out.println("localdatetime to localtime\t" + dtf.format(localdatetimetolocaltime));
    }

    @test
    public void test10(){
        simpledateformat sdf = new simpledateformat("yyyy-mm-dd hh:mm:ss");
        // localdatetime 转 date
        zoneid zoneid = zoneid.systemdefault();
        date localdatetimetodate = date.from(localdatetime.now().atzone(zoneid).toinstant());
        system.out.println("localdatetime to date\t" + sdf.format(localdatetimetodate));
    }

    @test
    public void test11(){
        simpledateformat sdf = new simpledateformat("yyyy-mm-dd hh:mm:ss");
        // localdate 转 date
        date localdatetodate = date.from(localdate.now().atstartofday(zoneid.systemdefault()).toinstant());
        system.out.println("localdate to date\t" + sdf.format(localdatetodate));
    }

    @test
    public void test12(){
        datetimeformatter dtf = datetimeformatter.ofpattern("yyyy-mm-dd hh:mm:ss");
        // 时间戳 转 localdatetime
        long timestamp = localdatetime.now().toinstant(zoneoffset.of("+8")).toepochmilli();
        localdatetime time2 = localdatetime.ofepochsecond(timestamp/1000,0,zoneoffset.ofhours(8));
        system.out.println("时间戳 to localdatetime\t" + dtf.format(time2));
    }