isShowSelect: false,
        dataList: [
          {key: -1, value: "POST"},
          {key: 0, value: "GET"},
          {key: 1, value: "DELETE"},
			    {key: 2, value: "PUT"}
        ],
        unitName:'请选择',
这些是写在data里的

<view class="right-date" style="width: 100px;font-size: 20upx;"@click="arrowDown" >
	<uni-icon type="arrowdown" size="20"></uni-icon>
	<p style="font-size: 20upx;" title="请选择">{{unitName}}</p>
</view>
<view class="selectBox_list" v-show="isShowSelect">
	<view class="selectBox_listLi" v-for="(item, index) in dataList" :key="index" @click.stop="select(item, index)">{{item.value}}
	 </view>
</view>

css样式，你们自己写吧，给selectBox_list绝对定位就可以了

      arrowDown() {
        this.isShowSelect = !this.isShowSelect;
      },
      select(item, index) {
        this.isShowSelect = false;
        this.unitName = item.value;
      },
这些是写在methods里的