如何将HH：mm：ss.SSS转换为毫秒？ [英] How to convert HH:mm:ss.SSS to milliseconds?

问题描述

我有一个String 00：01：30.500 ，相当于 90500 毫秒。我尝试使用 SimpleDateFormat ，它给出了毫秒，包括当前日期。我只需要字符串表示毫秒。我是否必须编写自定义方法，它将分割并计算毫秒数？或者还有其他办法吗？谢谢。

I have a String 00:01:30.500 which is equivalent to 90500 milliseconds. I tried using SimpleDateFormat which give milliseconds including current date. I just need that String representation to milliseconds. Do I have to write custom method, which will split and calculate milliseconds? or Is there any other way to do this? Thanks.

我尝试过如下：

        String startAfter = "00:01:30.555";
        SimpleDateFormat dateFormat = new SimpleDateFormat("HH:mm:ss.SSS");
        Date date = dateFormat.parse(startAfter);
        System.out.println(date.getTime());

推荐答案

您可以使用 SimpleDateFormat 这样做。你只需知道两件事。

You can use SimpleDateFormat to do it. You just have to know 2 things.

1. 所有日期在内部用UTC表示


2. .getTime（） 返回自1970-01-01 00:00:00 UTC以来的毫秒数。

1. All dates are internally represented in UTC
2. .getTime() returns the number of milliseconds since 1970-01-01 00:00:00 UTC.

package se.wederbrand.milliseconds;

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

public class Main {        
    public static void main(String[] args) throws Exception {
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSS");
        sdf.setTimeZone(TimeZone.getTimeZone("UTC"));

        String inputString = "00:01:30.500";

        Date date = sdf.parse("1970-01-01 " + inputString);
        System.out.println("in milliseconds: " + date.getTime());        
    }
}

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