通过 Bootstrap4对列进行排序

You can do two different container one with mobile order and hide on desktop screen, another with desktop order and hide on mobile screen

I'm using Bootstrap 3, so i don't know if there is an easier way to do it Bootstrap 4 but this css should work for you:

.pull-right-xs {
float: right;
}


@media (min-width: 768px) {
.pull-right-xs {
float: left;
}
}

...and add class to second column:

<div class="row">
<div class="col-xs-3 col-md-6">
1
</div>
<div class="col-xs-3 col-md-6 pull-right-xs">
2
</div>
<div class="col-xs-6 col-md-12">
3
</div>
</div>

EDIT:

Ohh... it looks like what i was writen above is exacly a .pull-xs-right class in Bootstrap 4 :X Just add it to second column and it should work perfectly.

2021 - Bootstrap 5

The responsive ordering classes are now order-first, order-last and order-0 - order-5

Demo

2018 - Bootstrap 4

The responsive ordering classes are now order-first, order-last and order-0 - order-12

Bootstrap 4.1+

Since Bootstrap 4 is flexbox, it's easy to change the order of columns. The cols can be ordered from order-1 to order-12, responsively such as order-md-12 order-2 (last on md, 2nd on xs) relative to the parent .row.

<div class="container">
<div class="row">
<div class="col-3 col-md-6">
<div class="card card-body">1</div>
</div>
<div class="col-6 col-md-12 order-2 order-md-12">
<div class="card card-body">3</div>
</div>
<div class="col-3 col-md-6 order-3">
<div class="card card-body">2</div>
</div>
</div>
</div>

Demo: Change order using order-* classes

Desktop (larger screens):

Mobile (smaller screens):

It's also possible to change column order using the flexbox direction utils...

<div class="container">
<div class="row flex-column-reverse flex-md-row">
<div class="col-md-8">
2
</div>
<div class="col-md-4">
1st on mobile
</div>
</div>
</div>

Demo: Bootstrap 4.1 Change Order with Flexbox Direction

Older version demos
demo - alpha 6
demo - beta (3)

See more Bootstrap 4.1+ ordering demos

Related
Column ordering in Bootstrap 4 with push/pull and col-md-12
Bootstrap 4 change order of columns

A-C-B A-B-C

Since column-ordering doesn't work in Bootstrap 4 beta as described in the code provided in the revisited answer above, you would need to use the following (as indicated in the codeply 4 Flexbox order demo - alpha/beta links that were provided in the answer).

<div class="container">
<div class="row">
<div class="col-3 col-md-6">
<div class="card card-block">1</div>
</div>
<div class="col-6 col-md-12  flex-md-last">
<div class="card card-block">3</div>
</div>
<div class="col-3 col-md-6 ">
<div class="card card-block">2</div>
</div>
</div>

Note however that the "Flexbox order demo - beta" goes to an alpha codebase, and changing the codebase to Beta (and running it) results in the divs incorrectly displaying in a single column -- but that looks like a codeply issue since cutting and pasting the code out of codeply works as described.

This can also be achieved with the CSS "Order" property and a media query.

Something like this:

@media only screen and (max-width: 768px) {
#first {
order: 2;
}
#second {
order: 4;
}
#third {
order: 1;
}
#fourth {
order: 3;
}
}

CodePen Link: https://codepen.io/preston206/pen/EwrXqm

even this will work:

<div class="container">
<div class="row">
<div class="col-4 col-sm-4 col-md-6 order-1">
1
</div>
<div class="col-4 col-sm-4  col-md-6 order-3">
2
</div>
<div class="col-4 col-sm-4  col-md-12 order-2">
3
</div>
</div>
</div>