这篇文章给大家分享的是有关怎么基于js管理大文件上传及断点续传的内容。小编觉得挺实用的，因此分享给大家做个参考，一起跟随小编过来看看吧。
图解：
页面展示
项目依赖
目录结构
Axios的简单封装
let instance = axios.create();
instance.defaults.baseURL = 'http://127.0.0.1:8888';
instance.defaults.headers['Content-Type'] = 'multipart/form-data';
instance.defaults.transformRequest = (data, headers) => {
const contentType = headers['Content-Type'];
if (contentType === "application/x-www-form-urlencoded") return Qs.stringify(data);
return data;
};
instance.interceptors.response.use(response => {
return response.data;
});文件上传一般是基于两种方式，FormData以及Base64
//前端代码
// 主要展示基于ForData实现上传的核心代码
upload_button_upload.addEventListener('click', function () {
if (upload_button_upload.classList.contains('disable') || upload_button_upload.classList.contains('loading')) return;
if (!_file) {
alert('请您先选择要上传的文件~~');
return;
}
changeDisable(true);
// 把文件传递给服务器：FormData
let formData = new FormData();
// 根据后台需要提供的字段进行添加
formData.append('file', _file);
formData.append('filename', _file.name);
instance.post('/upload_single', formData).then(data => {
if (+data.code === 0) {
alert(`文件已经上传成功~~,您可以基于 ${data.servicePath} 访问这个资源~~`);
return;
}
return Promise.reject(data.codeText);
}).catch(reason => {
alert('文件上传失败，请您稍后再试~~');
}).finally(() => {
clearHandle();
changeDisable(false);
});
});export changeBASE64(file) => {
return new Promise(resolve => {
let fileReader = new FileReader();
fileReader.readAsDataURL(file);
fileReader.onload = ev => {
resolve(ev.target.result);
};
});
};具体实现
upload_inp.addEventListener('change', async function () {
let file = upload_inp.files[0],
BASE64,
data;
if (!file) return;
if (file.size > 2 * 1024 * 1024) {
alert('上传的文件不能超过2MB~~');
return;
}
upload_button_select.classList.add('loading');
// 获取Base64
BASE64 = await changeBASE64(file);
try {
data = await instance.post('/upload_single_base64', {
// encodeURIComponent(BASE64) 防止传输过程中特殊字符乱码，同时后端需要用decodeURIComponent进行解码
file: encodeURIComponent(BASE64),
filename: file.name
}, {
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 ${data.servicePath} 地址去访问~~`);
return;
}
throw data.codeText;
} catch (err) {
alert('很遗憾，文件上传失败，请您稍后再试~~');
} finally {
upload_button_select.classList.remove('loading');
}
**});**上面这个例子中后端收到前端传过来的文件会对它进行生成一个随机的名字，存下来，但是有些公司会将这一步放在前端进行，生成名字后一起发给后端，接下来我们来实现这个功能
这里就需要用到上面提到的插件SparkMD5,具体怎么用就不做赘述了，请参考文档
封装读取文件流的方法
const changeBuffer = file => {
return new Promise(resolve => {
let fileReader = new FileReader();
fileReader.readAsArrayBuffer(file);
fileReader.onload = ev => {
let buffer = ev.target.result,
spark = new SparkMD5.ArrayBuffer(),
HASH,
suffix;
spark.append(buffer);
// 得到文件名
HASH = spark.end();
// 获取后缀名
suffix = /\.([a-zA-Z0-9]+)$/.exec(file.name)[1];
resolve({
buffer,
HASH,
suffix,
filename: `${HASH}.${suffix}`
});
};
});
};上传服务器相关代码
upload_button_upload.addEventListener('click', async function () {
if (checkIsDisable(this)) return;
if (!_file) {
alert('请您先选择要上传的文件~~');
return;
}
changeDisable(true);
// 生成文件的HASH名字
let {
filename
} = await changeBuffer(_file);
let formData = new FormData();
formData.append('file', _file);
formData.append('filename', filename);
instance.post('/upload_single_name', formData).then(data => {
if (+data.code === 0) {
alert(`文件已经上传成功~~,您可以基于 ${data.servicePath} 访问这个资源~~`);
return;
}
return Promise.reject(data.codeText);
}).catch(reason => {
alert('文件上传失败，请您稍后再试~~');
}).finally(() => {
changeDisable(false);
upload_abbre.style.display = 'none';
upload_abbre_img.src = '';
_file = null;
});
});这个功能相对来说比较简单，文中用到的请求库是axios,进度管控主要基于axios提供的onUploadProgress函数进行实现，这里一起看下这个函数的实现原理
监听xhr.upload.onprogress
文件上传后得到的对象
具体实现
(function () {
let upload = document.querySelector('#upload4'),
upload_inp = upload.querySelector('.upload_inp'),
upload_button_select = upload.querySelector('.upload_button.select'),
upload_progress = upload.querySelector('.upload_progress'),
upload_progress_value = upload_progress.querySelector('.value');
// 验证是否处于可操作性状态
const checkIsDisable = element => {
let classList = element.classList;
return classList.contains('disable') || classList.contains('loading');
};
upload_inp.addEventListener('change', async function () {
let file = upload_inp.files[0],
data;
if (!file) return;
upload_button_select.classList.add('loading');
try {
let formData = new FormData();
formData.append('file', file);
formData.append('filename', file.name);
data = await instance.post('/upload_single', formData, {
// 文件上传中的回调函数 xhr.upload.onprogress
onUploadProgress(ev) {
let {
loaded,
total
} = ev;
upload_progress.style.display = 'block';
upload_progress_value.style.width = `${loaded/total*100}%`;
}
});
if (+data.code === 0) {
upload_progress_value.style.width = `100%`;
alert(`恭喜您，文件上传成功，您可以基于 ${data.servicePath} 访问该文件~~`);
return;
}
throw data.codeText;
} catch (err) {
alert('很遗憾，文件上传失败，请您稍后再试~~');
} finally {
upload_button_select.classList.remove('loading');
upload_progress.style.display = 'none';
upload_progress_value.style.width = `0%`;
}
});
upload_button_select.addEventListener('click', function () {
if (checkIsDisable(this)) return;
upload_inp.click();
});
})();大文件上传一般采用切片上传的方式，这样可以提高文件上传的速度，前端拿到文件流后进行切片，然后与后端进行通讯传输，一般还会结合断点继传，这时后端一般提供三个接口，第一个接口获取已经上传的切片信息，第二个接口将前端切片文件进行传输，第三个接口是将所有切片上传完成后告诉后端进行文件合并
进行切片，切片的方式分为固定数量以及固定大小，我们这里两者结合一下
// 实现文件切片处理 「固定数量 & 固定大小」
let max = 1024 * 100,
count = Math.ceil(file.size / max),
index = 0,
chunks = [];
if (count > 100) {
max = file.size / 100;
count = 100;
}
while (index < count) {
chunks.push({
// file文件本身就具有slice方法，见下图
file: file.slice(index * max, (index + 1) * max),
filename: `${HASH}_${index+1}.${suffix}`
});
index++;
}发送至服务端
chunks.forEach(chunk => {
let fm = new FormData;
fm.append('file', chunk.file);
fm.append('filename', chunk.filename);
instance.post('/upload_chunk', fm).then(data => {
if (+data.code === 0) {
complate();
return;
}
return Promise.reject(data.codeText);
}).catch(() => {
alert('当前切片上传失败，请您稍后再试~~');
clear();
});
});文件上传 + 断电续传 + 进度管控
upload_inp.addEventListener('change', async function () {
let file = upload_inp.files[0];
if (!file) return;
upload_button_select.classList.add('loading');
upload_progress.style.display = 'block';
// 获取文件的HASH
let already = [],
data = null,
{
HASH,
suffix
} = await changeBuffer(file);
// 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,
count = Math.ceil(file.size / max),
index = 0,
chunks = [];
if (count > 100) {
max = file.size / 100;
count = 100;
}
while (index < count) {
chunks.push({
file: file.slice(index * max, (index + 1) * max),
filename: `${HASH}_${index+1}.${suffix}`
});
index++;
}
// 上传成功的处理
index = 0;
const clear = () => {
upload_button_select.classList.remove('loading');
upload_progress.style.display = 'none';
upload_progress_value.style.width = '0%';
};
const complate = async () => {
// 管控进度条
index++;
upload_progress_value.style.width = `${index/count*100}%`;
// 当所有切片都上传成功，我们合并切片
if (index < count) return;
upload_progress_value.style.width = `100%`;
try {
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 ${data.servicePath} 访问该文件~~`);
clear();
return;
}
throw data.codeText;
} catch (err) {
alert('切片合并失败，请您稍后再试~~');
clear();
}
};
// 把每一个切片都上传到服务器上
chunks.forEach(chunk => {
// 已经上传的无需在上传
if (already.length > 0 && already.includes(chunk.filename)) {
complate();
return;
}
let fm = new FormData;
fm.append('file', chunk.file);
fm.append('filename', chunk.filename);
instance.post('/upload_chunk', fm).then(data => {
if (+data.code === 0) {
complate();
return;
}
return Promise.reject(data.codeText);
}).catch(() => {
alert('当前切片上传失败，请您稍后再试~~');
clear();
});
});
}); // 大文件切片上传 & 合并切片
const merge = function merge(HASH, count) {
return new Promise(async (resolve, reject) => {
let path = `${uploadDir}/${HASH}`,
fileList = [],
suffix,
isExists;
isExists = await exists(path);
if (!isExists) {
reject('HASH path is not found!');
return;
}
fileList = fs.readdirSync(path);
if (fileList.length < count) {
reject('the slice has not been uploaded!');
return;
}
fileList.sort((a, b) => {
let reg = /_(\d+)/;
return reg.exec(a)[1] - reg.exec(b)[1];
}).forEach(item => {
!suffix ? suffix = /\.([0-9a-zA-Z]+)$/.exec(item)[1] : null;
fs.appendFileSync(`${uploadDir}/${HASH}.${suffix}`, fs.readFileSync(`${path}/${item}`));
fs.unlinkSync(`${path}/${item}`);
});
fs.rmdirSync(path);
resolve({
path: `${uploadDir}/${HASH}.${suffix}`,
filename: `${HASH}.${suffix}`
});
});
};
app.post('/upload_chunk', async (req, res) => {
try {
let {
fields,
files
} = await multiparty_upload(req);
let file = (files.file && files.file[0]) || {},
filename = (fields.filename && fields.filename[0]) || "",
path = '',
isExists = false;
// 创建存放切片的临时目录
let [, HASH] = /^([^_]+)_(\d+)/.exec(filename);
path = `${uploadDir}/${HASH}`;
!fs.existsSync(path) ? fs.mkdirSync(path) : null;
// 把切片存储到临时目录中
path = `${uploadDir}/${HASH}/${filename}`;
isExists = await exists(path);
if (isExists) {
res.send({
code: 0,
codeText: 'file is exists',
originalFilename: filename,
servicePath: path.replace(__dirname, HOSTNAME)
});
return;
}
writeFile(res, path, file, filename, true);
} catch (err) {
res.send({
code: 1,
codeText: err
});
}
});
app.post('/upload_merge', async (req, res) => {
let {
HASH,
count
} = req.body;
try {
let {
filename,
path
} = await merge(HASH, count);
res.send({
code: 0,
codeText: 'merge success',
originalFilename: filename,
servicePath: path.replace(__dirname, HOSTNAME)
});
} catch (err) {
res.send({
code: 1,
codeText: err
});
}
});
app.get('/upload_already', async (req, res) => {
let {
HASH
} = req.query;
let path = `${uploadDir}/${HASH}`,
fileList = [];
try {
fileList = fs.readdirSync(path);
fileList = fileList.sort((a, b) => {
let reg = /_(\d+)/;
return reg.exec(a)[1] - reg.exec(b)[1];
});
res.send({
code: 0,
codeText: '',
fileList: fileList
});
} catch (err) {
res.send({
code: 0,
codeText: '',
fileList: fileList
});
}
});感谢各位的阅读！关于“怎么基于js管理大文件上传及断点续传”这篇文章就分享到这里了，希望以上内容可以对大家有一定的帮助，让大家可以学到更多知识，如果觉得文章不错，可以把它分享出去让更多的人看到吧！
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