如何實(shí)現基于React-Dropzone開(kāi)發(fā)上傳組件功能

這篇文章將為大家詳細講解有關(guān)如何實(shí)現基于React-Dropzone開(kāi)發(fā)上傳組件功能，小編覺(jué)得挺實(shí)用的，因此分享給大家做個(gè)參考，希望大家閱讀完這篇文章后可以有所收獲。

實(shí)例演示

1. axios上傳普通文件：

通過(guò)yarn將react-dropzone和引入：

yarn add react-dropzone axios

前端js如下(如有缺失，請自行修改)：

import React, { 
    useState, 
    useCallback,
    useEffect,
} from 'react';
import {useDropzone} from 'react-dropzone';
import "./dropzone.styles.css"
import InfiniteScroll from 'react-infinite-scroller';
import {
    List,
    message,
    // Avatar,
    Spin,
} from 'antd';
import axios from 'axios';

/**
* 計算文件大小
* @param {*} bytes 
* @param {*} decimals 
* @returns 
*/
function formatBytes(bytes, decimals = 2) {
    if (bytes === 0) return '0 Bytes';

    const k = 1024;
    const dm = decimals < 0 ? 0 : decimals;
    const sizes = ['Bytes', 'KB', 'MB', 'GB', 'TB', 'PB', 'EB', 'ZB', 'YB'];

    const i = Math.floor(Math.log(bytes) / Math.log(k));

    return parseFloat((bytes / Math.pow(k, i)).toFixed(dm)) + ' ' + sizes[i];
}

/**
* Dropzone 上傳文件
* @param {*} props 
* @returns 
*/
function DropzoneUpload(props) {
    const [files, setFiles] = useState([])
    const [loading, setLoading] = useState(false);
    const [hasMore, setHasMore] = useState(true);

    const onDrop = useCallback(acceptedFiles => {
        setLoading(true);
        const formData = new FormData();
        smallFiles.forEach(file => {
            formData.append("files", file);
        });
        axios({
            method: 'POST',
            url: '/api/files/multiplefiles',
            data: formData,
            headers: {
                "Content-Type": "multipart/form-data",
            }
        })
        then(resp => {
            addFiles(acceptedFiles);
            setLoading(false);
        });
    }, [files]);

    // Dropzone setting
    const { getRootProps, getInputProps } = useDropzone({
        multiple:true,
        onDrop,
    });

    // 刪除附件
    const removeFile = file => {
        const newFiles = [...files]
        newFiles.splice(newFiles.indexOf(file), 1)
        setFiles(newFiles)
    }

    useEffect(() => {
        // init uploader files
        setFiles([])
    },[])

    return (
        <section className="container">
        <div {...getRootProps({className: 'dropzone'})}>
            <input {...getInputProps()} />
            <p>拖動(dòng)文件或點(diǎn)擊選擇文件?</p>
        </div>
        
        <div className="demo-infinite-container">
            <InfiniteScroll
                initialLoad={false}
                pageStart={0}
                loadMore={handleInfiniteOnLoad}
                hasMore={!loading && hasMore}
                useWindow= {false}
            >
                <List
                    dataSource={files}
                    renderItem={item=> (
                        <List.Item 
                            actions={[
                                // <a key="list-loadmore-edit">編輯</a>, 
                                <a key="list-loadmore-delete" onClick={removeFile}>刪除</a>
                            ]}
                            // extra={
                                
                            // }
                            key={item.path}>
                            <List.Item.Meta 
                                avatar={
                                    <>
                                    {
                                        !!item.type && ['image/gif', 'image/jpeg', 'image/png'].includes(item.type) &&
                                        <img 
                                            width={100}
                                            alt='logo'
                                            src={item.preview}
                                        />
                                    }
                                    </>
                                }
                                title={item.path}
                                description={formatBytes(item.size)}
                            />
                        </List.Item>
                    )}
                >
                    {loading && hasMore && (
                        <div className="demo-loading-container">
                            <Spin />
                        </div>
                    )}
                </List>
            </InfiniteScroll>
        </div>
        </section>
    );
}

flask代碼：

def multiplefiles():
if 'files' not in request.files:
    return jsonify({'message': '沒(méi)有文件！'}), 200
files = request.files.getlist('files')

for file in files:
    if file:
        # 通過(guò)拼音解決secure_filename中文問(wèn)題
        filename = secure_filename(''.join(lazy_pinyin(file.filename))
        Path(UPLOAD_FOLDER + '/' + file_info['dir_path']).mkdir(parents=True, exist_ok=True)
        file.save(os.path.join(UPLOAD_FOLDER + '/' + file_info['dir_path'], filename))

return jsonify({'message': '保存成功??！'})

2. 大文件導入：

通過(guò)file.slice()方法生成文件的chunks。不要用Promise.all容易產(chǎn)生非順序型的請求，導致文件損壞。

js代碼：

const promiseArray = largeFiles.map(file => new Promise((resolve, reject) => {
                        
    const chunkSize = CHUNK_SIZE;
    const chunks = Math.ceil(file.size / chunkSize);
    let chunk = 0;
    let chunkArray = new Array();
    while (chunk <= chunks) {
        let offset = chunk * chunkSize;
        let slice = file.slice(offset, offset+chunkSize)
        chunkArray.push([slice, offset])
        ++chunk;
    }
    const chunkUploadPromises = (slice, offset) => {
        const largeFileData = new FormData();
        largeFileData.append('largeFileData', slice)
        return new Promise((resolve, reject) => {
            axios({
                method: 'POST',
                url: '/api/files/largefile',
                data: largeFileData,
                headers: {
                    "Content-Type": "multipart/form-data"
                }
            })
            .then(resp => {
                console.log(resp);
                resolve(resp);
            })
            .catch(err => {
                reject(err);
            })
        })
    };

    chunkArray.reduce( (previousPromise, [nextChunk, nextOffset]) => {
        return previousPromise.then(() => {
            return chunkUploadPromises(nextChunk, nextOffset);
        });
    }, Promise.resolve());
    resolve();
}))

flask代碼：

filename = secure_filename(''.join(lazy_pinyin(filename)))
Path(UPLOAD_FOLDER + '/' + file_info['dir_path']).mkdir(parents=True, exist_ok=True)
save_path = os.path.join(UPLOAD_FOLDER + '/' + file_info['dir_path'], filename)
try:
    with open(save_path, 'ab') as f:
        f.seek(offset)
        f.write(file.stream.read())
        print("time： "+ str(datetime.now())+" offset: " + str(offset))
except  OSError:
    return jsonify({'Could not write to file'}), 500