java JSTL 舍入/向下数
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JSTL Round off/down number
提问by user1386375
This might be a dumb question, but let's say I have a variable secondsin my JSP page and its value is 779. Now I want to convert it into minutes and seconds by doing the following:
这可能是一个愚蠢的问题，但假设seconds我的 JSP 页面中有一个变量，其值为 779。现在我想通过执行以下操作将其转换为分钟和秒：
<c:set var="${seconds / 60}" value="min"/>
<c:set var="${seconds mod 60}" value="sec">
This way I get min = 12.983333 and sec = 59.0.
这样我得到 min = 12.983333 和 sec = 59.0。
Now I want to merge the two and display the result as 12:59. The problem I am facing is that minkeeps getting rounded up to 13. I have tried many things, such as:
现在我想合并两者并将结果显示为 12:59。我面临的问题是min不断四舍五入到 13。我尝试了很多东西，例如：
<fmt:parseNumber var="minutes" integerOnly="true" type="number" value="${min}" />
<fmt:formatNumber type="number" pattern="###" value="${min}" var="minutes" />
fn:substringBefore(min, '.')
maxFractionDigits="0"
// and so on...
But all of them just return 13 consistently. I am a bit clueless at this point. But I may have missed something. I hope someone here has an idea, or a hint, about what might be wrong.
但他们都只是一致地返回 13。在这一点上，我有点不知所措。但我可能错过了一些东西。我希望这里有人对可能出现的问题有想法或提示。
-edit
-编辑
The code below made it work in the end. I have no clue what was wrong, since its also working with "/" now. Maybe some minor mistake elsewhere. Nevertheless thanks a lot for your time :) Kudos!
下面的代码使它最终工作。我不知道出了什么问题，因为它现在也使用“/”。也许其他地方的一些小错误。不过非常感谢您的时间:) 荣誉！
<c:set var="min" value="${fn:substringBefore((seconds div 60), '.')}"/>
<fmt:formatNumber var="sec" pattern="##" value="${seconds mod 60)}"/>
回答by Serge Miche9
This (below) should be the only safe way to do it. pattern="##" is not well supported, minIntegerDigits="2" is easier and cleaner.
这（下面）应该是唯一安全的方法。pattern="##" 没有得到很好的支持， minIntegerDigits="2" 更容易和更干净。
<c:set var="minutes" value="${fn:substringBefore(seconds div 60, '.')}"/>
<fmt:formatNumber var="seconds" minIntegerDigits="2" value="${ seconds - (minutes*60) }"/>
回答by buc
Use integral division to get the value for min, instead of floating point division:
使用整数除法来获取 的值min，而不是浮点除法：
<c:set var="min" value="${seconds div 60}" />
Now you get min = 12, and you don't have to worry about the rounding issues.
现在您得到 min = 12，并且您不必担心舍入问题。
