JavaScript利用切片实现大文件断点续传

  url:/upload_already
  method:GET
  params:
    HASH:文件的HASH名字
  return:application/JSON
    code:0成功 1失败,
    codeText:状态描述,
    fileList:[...]

{
fileList:['f07ec272dbb0b883eed4b2f415625a90_1.mp4','f07ec272dbb0b883eed4b2f415625a90_2.mp4','f07ec272dbb0b883eed4b2f415625a90_3.mp4']
}

  url:/upload_chunk
  method:POST
  params:multipart/fORM-data
    file:切片数据
    filename:切片名字「文件生成的HASH_切片编号.后缀」
  return:application/json
    code:0成功 1失败,
    codeText:状态描述,
    originalFilename:文件原始名称,
    servicePath:文件服务器地址

  url:/upload_merge
  method:POST
  params:application/x-www-form-urlencoded
    HASH:文件的HASH名字
    count:切片数量
  return:application/json
    code:0成功 1失败,
    codeText:状态描述,
    originalFilename:文件原始名称,
    servicePath:文件服务器地址

const changeBuffer = file => {
    return new Promise(resolve => {
        let fileReader = new FileReader();
        fileReader.readAsArrayBuffer(file);
        fileReader.onload = ev => {
            let buffer = ev.target.result,
                spark = new SparkMD5.ArrayBuffer(),
                HASH,
                suffix;
            spark.append(buffer);
            HASH = spark.end();
            suffix = /.([a-zA-Z0-9]+)$/.exec(file.name)[1];
            resolve({
                buffer,
                HASH,
                suffix,
                filename: `${HASH}.${suffix}`
            });
        };
    });
};

<div class="container">
    <div class="item">
        <h3>大文件上传</h3>
        <section class="upload_box" id="upload7">
            <input type="file" class="upload_inp">
            <div class="upload_button_box">
                <button class="upload_button select">上传文件</button>
            </div>
            <div class="upload_progress">
                <div class="value"></div>
            </div>
        </section>
    </div>
</div>

//创建一个单独的实例,不去项目全局的或者其他的axios冲突
let instance = axios.create();
instance.defaults.baseURL = 'Http://127.0.0.1:8888';
//默认是multipart/form-data格式
instance.defaults.headers['Content-Type'] = 'multipart/form-data';
instance.defaults.transformRequest = (data, headers) => {
    //兼容x-www-form-urlencoded格式的请求发送
    const contentType = headers['Content-Type'];
    if (contentType === "application/x-www-form-urlencoded") return Qs.stringify(data);
    return data;
};
//统一结果的处理
instance.interceptors.response.use(response => {
    return response.data;
},reason=>{
    //统一失败的处理
    return Promise.reject(reason)
});

(function () {
    let upload = document.querySelector('#upload7'),
        upload_inp = upload.querySelector('.upload_inp'),
        upload_button_select = upload.querySelector('.upload_button.select'),
        upload_progress = upload.querySelector('.upload_progress'),
        upload_progress_value = upload_progress.querySelector('.value');

    const checkIsDisable = element => {
        let classList = element.classList;
        return classList.contains('disable') || classList.contains('loading');
    };

    
    const changeBuffer = file => {
        return new Promise(resolve => {
            let fileReader = new FileReader();
            fileReader.readAsArrayBuffer(file);
            fileReader.onload = ev => {
                let buffer = ev.target.result,
                    spark = new SparkMD5.ArrayBuffer(),
                    HASH,
                    suffix;
                spark.append(buffer);
                HASH = spark.end();
                suffix = /.([a-zA-Z0-9]+)$/.exec(file.name)[1];
                resolve({
                    buffer,
                    HASH,
                    suffix,
                    filename: `${HASH}.${suffix}`
                });
            };
        });
    };

    upload_inp.addEventListener('change', async function () {
        //get native file object
        let file = upload_inp.files[0];
        if (!file) return;
        //button add loading
        upload_button_select.classList.add('loading');
        //show progress
        upload_progress.style.display = 'block';

        // 获取文件的HASH
        let already = [],//已经上传过的切片的切片名
            data = null,
            {
                HASH,
                suffix
            } = await changeBuffer(file);//得到原始文件的hash和后缀

        // 获取已经上传的切片信息
        try {
            data = await instance.get('/upload_already', {
                params: {
                    HASH
                }
            });
            if (+data.code === 0) {
                already = data.fileList;
            }
        } catch (err) {}

        // 实现文件切片处理 「固定数量 & 固定大小」
        let max = 1024 * 100,//切片大小先设置100KB
            count = Math.ceil(file.size / max),//得到应该上传的切片
            index = 0,//存放切片数组的时候遍历使用
            chunks = [];//用以存放切片值
        if (count > 100) {//如果切片数量超过100,那么就只切成100个,因为切片太多的话也会影响调用接口的速度
            max = file.size / 100;
            count = 100;
        }
        while (index < count) {//循环生成切片
            //index 0 =>  0~max
            //index 1 =>  max~max*2
            //index*max ~(index+1)*max
            chunks.push({
                file: file.slice(index * max, (index + 1) * max),
                filename: `${HASH}_${index+1}.${suffix}`
            });
            index++;
        }

        index = 0;
        const clear = () => {//上传完成后,将状态回归
            upload_button_select.classList.remove('loading');
            upload_progress.style.display = 'none';
            upload_progress_value.style.width = '0%';
        };

        //每一次上传一个切片成功的处理[进度管控&切片合并]
        const complate = async () => {
            // 管控进度条:每上传完一个切片,就将进度条长度增加一点
            index++;
            upload_progress_value.style.width = `${index/count*100}%`;

            if (index < count) return;
            // 当所有切片都上传成功，就合并切片
            upload_progress_value.style.width = `100%`;
            try {
                //调用合并切片方法
                data = await instance.post('/upload_merge', {
                    HASH,
                    count
                }, {
                    headers: {
                        'Content-Type': 'application/x-www-form-urlencoded'
                    }
                });
                if (+data.code === 0) {
                    alert(`恭喜您，文件上传成功，您可以基于 ${data.servicePath} 访问该文件~~`);
                    clear();
                    return;
                }
                throw data.codeText;
            } catch (err) {
                alert('切片合并失败，请您稍后再试~~');
                clear();
            }
        };

        // 循环上传每一个切片
        chunks.forEach(chunk => {
            // 已经上传的无需在上传
            //后台返回的already格式为['HASH_1.png','HASH_2.png'],既已经上传的文件的切片名
            if (already.length > 0 && already.includes(chunk.filename)) {
                //已经上传过了的切片就无需再调用接口上传了
                complate();//动进度条或合并所有切片
                return;
            }
            let fm = new FormData;
            fm.append('file', chunk.file);
            fm.append('filename', chunk.filename);
            instance.post('/upload_chunk', fm).then(data => {//使用form data格式上传切片
                if (+data.code === 0) {
                    complate();////动进度条或合并所有切片
                    return;
                }
                return Promise.reject(data.codeText);
            }).catch(() => {
                alert('当前切片上传失败，请您稍后再试~~');
                clear();
            });
        });
    });
    //触发原生的上传文件框
    upload_button_select.addEventListener('click', function () {
        if (checkIsDisable(this)) return;
        upload_inp.click();
    });
})();