Timestamp formatting "recommended collection"

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一、须知：

1. Pure numeric timestamp minutes2种,一种是10位的,Only the year, month, day, hour, minute, and second are included,也就是说,只精确到秒.一种是13位的,包含毫秒.这2Both are called timestamps,Timestamps are not only accurate to milliseconds.

10The bit timestamp is from1970-01-01到当前的秒数,注意,Not milliseconds,So you need to parse by milliseconds,要 * 1000 13The bit timestamp is from1970-01-01到当前的毫秒数,在java中用Instant对象对应.

2. timestampThe format string is capitalizedSto represent milliseconds.SThe number of bits strictly corresponds to the number of milliseconds,否则报错.If the specification requires precision to the millisecond,Then give the time string,那肯定是3位.给2Bit accurate to less than a millisecond,给4位,The number of milliseconds obtained will also not contain information beyond the milliseconds.

  @Test
  def tt3(): Unit = { 
   
    val dtf = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss.SSS")
    //Timestamps and time objects are interchangeable
    println(LocalDateTime.parse("2020-04-04 08:08:08.123", dtf).toInstant(ZoneOffset.of("+8")).toEpochMilli) //1585958888123
    println(LocalDateTime.ofInstant(Instant.ofEpochMilli(1585958888123L), ZoneOffset.of("+8"))) //2020-04-04T08:08:08.123

    //这2个值是一样的,The parsing seconds above,下面的是 * 1000 Post-parse milliseconds
    println(LocalDateTime.ofEpochSecond(1585958888L, 0, ZoneOffset.ofHours(8))) //2020-04-04T08:08:08
    println(LocalDateTime.ofInstant(Instant.ofEpochMilli(1585958888000L), ZoneOffset.of("+8"))) //2020-04-04T08:08:08
  }

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3. LocalDateTime.ofEpochSecond(1585958888L, 0, ZoneOffset.ofHours(8))Used to convert seconds to a time object.LocalDateTime.ofInstant(Instant.ofEpochMilli(1585958888000L), ZoneOffset.of(“+8”))Used to convert milliseconds to a time object.Epoch的意思是从1970-01-01开始.

二、HiveSupport for timestamps in

Hive并没有提供13Conversion function for bit timestamps,但是load的时候,It will automatically recognize the shape as”2020-04-04 08:08:08.123″This timestamp with milliseconds,It will import normally and display and use normally.

Hive中10Conversion of bit-only numeric timestamps： https://www.cnblogs.com/dcx-1993/p/11359139.html

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