html:
<div class="parent">
<div class="son">1</div>
<div class="son">2</div>
<div class="son">3</div>
<div class="son">4</div>
</div>
css:
.parent{
width: 600px;
height: auto;
border: 10px solid black;
display: flex;
/*flex-direction: row; //水平排列(默认)*/
/*flex-direction: column; //垂直排列*/
/*flex-wrap: wrap;//换行*/
/*flex-wrap: nowrap;//不换行(默认)*/
/*justify-content: center;//居中排列*/
/*justify-content: flex-start //靠左排列*/
/*justify-content: flex-end //靠右排列*/
/*justify-content: space-between; //两端对齐,中间间隔相等*/
/*justify-content: space-around; //每个元素两侧间隔相等,所以中间比两端间隔大一倍*/
/*align-items: center; //在竖直方向居中*/
/*align-items: flex-start;//在竖直方向顶部*/
/*align-items: flex-end;//在竖直方向底部*/
}
.son{
width: 100px;
height: 100px;
background: peachpuff;
border: 1px solid black;
}
css解析:
.parent{ flex-direction:row(默认) | row-reverse | column | column-reverse; }
.parent{
flex-wrap: nowrap(默认不换行) |wrap;}不换行效果图:

换行效果图:

.parent{ justify-content: center;//居中排列}居中排列效果图:

.parent{ justify-content: flex-start //靠左排列}
flex-start:

.parent{ justify-content: flex-end //靠右排列}
flex-end:

.parent{ justify-content: space-between; //两端对齐,中间间隔相等}
space-between:

.parent{ justify-content: space-around; //每个元素两侧间隔相等,所以中间比两端间隔大一倍}
space-around:

.parent{ align-items: center; //在竖直方向居中}
效果图:

.parent{ align-items: flex-start;//在竖直方向顶部}
flex-start:

.parent{ align-items: flex-end;//在竖直方向底部}
flex-end: