回答react-dnd怎么实现拖拽

/*
 * @Author: muge
 * @Date: 2021-12-04 16:59:25
 * @LastEditors: Please set LastEditors
 * @LastEditTime: 2021-12-08 14:24:47
 */
import React, { useState } from 'react';
import { DndProvider } from 'react-dnd';
import { HTML5Backend } from 'react-dnd-html5-backend';
import SourceBox from './SourceBox';
import TargetBox from './TargetBox';
import TreeBox from './TreeBox';
const item: any[] = [
  {
    id: 1,
    name: 'muge',
  },
  {
    id: 2,
    name: 'muxi',
  },
  {
    id: 3,
    name: 'mugege',
  },
];
const Container = () => {
  // 当前拖拽项
  const [currentList, setCurrentList] = useState<any>({});
  return (
    // 类似redux数据传输  需要在最外层包裹对象
    <DndProvider backend={HTML5Backend}>
      <h1>拖拽源组件 列表-----树</h1>
      <div style={{ display: 'flex' }}>
        <div>
          {/* 列表拖拽源 */}
          {item.map((itemz: any, index: number) => (
            <SourceBox setCurrentList={setCurrentList} item={itemz} key={index} />
          ))}
        </div>
        {/* 注意，不要树组件整体直接设置拖拽，抽成一个组件来遍历每一项 =》自定义渲染*/}
        {/* 树形拖拽源 */}
        <TreeBox />
      </div>
      <h1>拖拽放置目标</h1>
      {/* 拖拽最终放置组件 */}
      <TargetBox currentList={currentList} />
    </DndProvider>
  );
};
export default Container;

/*
 * @Author: muge
 * @Date: 2021-12-07 14:26:08
 * @LastEditors: Please set LastEditors
 * @LastEditTime: 2021-12-08 14:18:52
 */
import { useDrag } from 'react-dnd';
const ItemTypes = {
  BOX: 'box',
};
const style = {
  border: '1px dashed gray',
  backgroundColor: 'white',
  padding: '0.5rem 1rem',
  marginRight: '1rem',
  marginBottom: '1rem',
  cursor: 'move',
};
const SourceBox = ({ item, setCurrentList }: any) => {
  const [{ opacity }, drag] = useDrag(
    () => ({
      type: ItemTypes.BOX,
      collect: (monitor) => ({
        opacity: monitor.isDragging() ? 0.4 : 1,
      }),
      item: () => item, //返回当前列表项数据
      canDrag: (monitor) => {
        //是否取消拖拽
        console.log(monitor, 'monitor131');
        return true;
      },
      //
      end(currentItem, monitor) {
        // monitor.getDropResult(); //获取拖拽对象所处容器的数据
        // monitor.didDrop(); // 当前容器能否放置拖拽对象 拖动停止时触发
        monitor.didDrop() && setCurrentList(currentItem); //在容器点松开 才赋值
      },
    }),
    [],
  );
  return (
    <div ref={drag} style={{ ...style, opacity }}>
      {item.id}------{item.name}
    </div>
  );
};
export default SourceBox;

/*
 * @Author: muge
 * @Date: 2021-12-07 14:26:08
 * @LastEditors: Please set LastEditors
 * @LastEditTime: 2021-12-08 14:33:08
 */
import React from 'react';
import { useDrop } from 'react-dnd';
const ItemTypes = {
  BOX: 'box',
};
const style: any = {
  border: '1px solid gray',
  height: '15rem',
  width: '15rem',
  padding: '2rem',
  textAlign: 'center',
};
const TargetBox = ({ currentList }: any) => {
  const [{ isActive, isOver, canDrop }, drop] = useDrop(() => ({
    accept: ItemTypes.BOX,
    collect: (monitor) => ({
      isActive: monitor.canDrop() && monitor.isOver(),
      isOver: monitor.isOver(),
      canDrop: monitor.canDrop(),
    }),
    // hover: (item, monitor) => {
    //   console.log(item, 'item');
    //   console.log(monitor, 'monitor');
    // },
  }));
  // console.log(isOver, 'isOver');
  // console.log(canDrop, 'canDrop');
  return (
    <div ref={drop} style={style}>
      {isActive ? 'Release to drop' : 'Drag item here'}
      <div
        style={{
          backgroundColor: 'pink',
          height: 30,
          display: 'flex',
          alignItems: 'center',
          justifyContent: 'center',
          fontSize: 17,
          fontWeight: 600,
          width: '100%',
        }}
      >
        {JSON.stringify(currentList) !== '{}' ? JSON.stringify(currentList) : '当前item'}
      </div>
    </div>
  );
};
export default TargetBox;