常用的flex布局介绍(水平居中和垂直居中)

<div class="outer_box">
  <div>1div>
  <div>2div>
  <div>3div>
  <div>4div>
  <div>5div>
  <div>6div>
div>

1.flex-direction

flex-direction:row;(默认)

.outer_box {
  display:flex;
  flex-direction:row;
  width:800px;
  border: 1px solid #000;
}

.outer_box div {
  width: 100px;
  height: 100px;
  background: skyblue;
  border:1px solid #000;
}

flex-direction:row-reverse;

.outer_box {
  display:flex;
  flex-direction:row-reverse;
  width:800px;
  border: 1px solid #000;
}

.outer_box div {
  width: 100px;
  height: 100px;
  background: skyblue;
  border:1px solid #000;
}

flex-direction:column;

.outer_box {
  display: flex;
  flex-direction:column;
  height: 800px;
  border: 1px solid #000;
}

.outer_box div {
  width: 100px;
  height: 100px;
  background: skyblue;
  border: 1px solid #000;
}

flex-direction:column-reserve;

.outer_box {
  display: flex;
  flex-direction:column-reverse;
  height: 800px;
  border: 1px solid #000;
}

.outer_box div {
  width: 100px;
  height: 100px;
  background: skyblue;
  border: 1px solid #000;
}

2.flex-wrap

flex-wrap:nowrap;(不换行，默认)

如果父盒子过小，装不下子盒子，则子盒子宽度变小

.outer_box {
  display:flex;
  flex-wrap:nowrap;
  width: 450px;
  border: 1px solid #000;
}

.outer_box div {
  width: 100px;
  height: 100px;
  background: skyblue;
  border:1px solid #000;
}

flex-wrap:wrap;(换行)

.outer_box {
  display:flex;
  flex-wrap:wrap;
  width: 450px;
  border: 1px solid #000;
}

.outer_box div {
  width: 100px;
  height: 100px;
  background: skyblue;
  border:1px solid #000;
}

flex-wrap:wrap-reverse;(换行)

.outer_box {
  display:flex;
  flex-wrap:wrap-reverse;
  width: 450px;
  border: 1px solid #000;
}

.outer_box div {
  width: 100px;
  height: 100px;
  background: skyblue;
  border:1px solid #000;
}

flex-flow:row nowrap;(默认，flex-direction和flex-wrap的简写)

3.justify-content

justify-content:center;(水平居中)

.outer_box {
  display:flex;
  justify-content:center;
  width: 1000px;
  border: 1px solid #000;
}

.outer_box div {
  width: 100px;
  height: 100px;
  background: skyblue;
  border:1px solid #000;
}

justify-content:space-between;（div之间间隔相等）

.outer_box {
  display:flex;
  justify-content:space-between;
  width:1000px;
  border:1px solid #000;
}
}

.outer_box div {
  width: 100px;
  height: 100px;
  background: skyblue;
  border:1px solid #000;
}

justify-content:space-around;（div两侧间隔相等）

.outer_box {
  display:flex;
  justify-content:space-around;
  width:200px;
  height: 800px;
  border: 1px solid #000;
}

.outer_box div {
  width: 100px;
  height: 100px;
  background: skyblue;
  border:1px solid #000;
}

4.justify-content

align-items: center;(垂直居中)

.outer_box {
  display: flex;
  align-items: center;
  height:200px;
  border:1px solid #000;
}

.outer_box div {
  width: 100px;
  height: 100px;
  background: skyblue;
  border: 1px solid #000;
}