业务需求需要el-transfer的功能，但是el-transfer未提供拖拽排序功能，网上没找到合适的轮子,就用el-tree进行了二次封装,效果如下

 附组件代码

<template>
  <div class="tc_transfer">
    <div class="tc_tree">
      <div class="tree_title">{{ sourceTitle }}</div>
      <el-tree class="tree_body"
               empty-text="可选列表为空"
               :data="sourceList"
               :default-checked-keys="checkKeys"
               @check-change="checkChange"
               node-key="id"
               show-checkbox>
      </el-tree>
    </div>
    <div class="tc_tree">
      <div class="tree_title">{{ targetTitle }}</div>
      <el-tree class="tree_body"
               empty-text="未选择"
               :data="targetList"
               node-key="id"
               draggable
               :allow-drop="allowDrop"
               @node-drag-end="dragEnd"
               v-slot="{node,data}"
      >
        <span class="tc-tree-node">
          {{ data.order + ': ' + data.label }}
        </span>
      </el-tree>
    </div>
  </div>
</template>

<script>
import {arrayRemoveByIndex} from "@/utils";

export default {
  data() {
    return {
      targetList: []
    }
  },
  props: {
    sourceList: {
      type: Array,
      default: []
    },
    checkKeys: {
      type: Array,
      default: []
    },
    sourceTitle: {
      type: String,
      default: null
    },
    targetTitle: {
      type: String,
      default: null
    }
  },
  methods: {
    gettxt(a) {
      console.log(a)
    },
    fetchData() {
      this.targetList = []
      for (let i = 0; i < this.checkKeys.length; i++) {
        let id = this.checkKeys[i];
        this.sourceList.forEach(source => {
          if (source.id === id) {
            let target = {}
            target.order = i + 1;
            target.id = source.id;
            target.label = source.label;
            this.targetList.push(target)
          }
        })
      }
    },
    checkChange(checkNode, changeType) {
      if (changeType) {
        let target = {}
        target.id = checkNode.id
        target.label = checkNode.label
        target.order = this.targetList.length + 1
        this.targetList.push(target)
      } else {
        for (let i = 0; i < this.targetList.length; i++) {
          let id = checkNode.id;
          if (this.targetList[i].id === id) {
            arrayRemoveByIndex(this.targetList, i);
          }
        }
      }
      this.updateKeys()
    },
    allowDrop(draggingNode, dropNode, type) {
      return type !== 'inner';
    },
    dragEnd() {
      //更新order值
      for (let i = 0; i < this.targetList.length; i++) {
        this.targetList[i].order = i + 1
      }

      this.updateKeys()
    },
    updateKeys() {
      //更新父类的值
      let checkKey = []
      this.targetList.forEach(item => {
        checkKey.push(item.id)
      })
      this.$emit('update:checkKeys', checkKey)
    }
  }
}

</script>
<style scoped>
.tc_transfer .tc_tree:nth-child(1) {
  margin-right: 6%;
}

.tc_tree {
  width: 47%;
  height: 300px;
  display: inline-block;
  vertical-align: top;
}

.tc_tree .tree_title {
  text-align: center;
  width: 100%;
  font-size: 18px;
  margin-bottom: 5px;
}

.tc_tree .tree_body {
  border: #666 solid 1px;
  border-radius: 5px;
  height: 300px;
  overflow-y: auto;
  padding: 5px 5px 5px 0;
}

</style>

export function arrayRemoveByIndex(array, index) {
    if (index > -1) {
        array.splice(index, 1);
    }
}