功能：
拖拽上传文件、图片，上传的进度条，能够同时上传多个文件。
完整的demo地址：https://github.com/qcer/FE-Components/tree/master/QDrag
涉及到的API：
1、HTML5的拖拽事件：dragenter，dragover，drop等
2、XMLHttpRequest Level2
3、FormData
4、（扩展：HTML5的File API）
概述：
1、利用拖拽实践的API将一个普通的div自定义成一个放置目标，这里有一个技巧是放置一个隐藏的input[type='file']的元素，在div上绑定input的点击事件，再点击事件中触发input的click事件，能够在div上任意位置达到type=file选择文件上传的效果。
2、在div的drag事件中获取文件对象，通过FormData对象构造表单序列化的数据，同时动态生成页面元素，通过XMLHttpRequest对象发送数据，在xhr.upload的progress事件中实现上传进度的功能。
3、后端通过nodejs实现一个http服务器，接受数据，进而可以扩展的解析数据。
前端页面代码：
<!DOCTYPE html>
<html>
<head>
<title></title>
<style type="text/css">
#qdrag{
height: 300px;
width: 100%;
background: #eee;
border-radius: 5px;
padding-top: 20px;
}
#qdrag-hidden {
display: none;
position: absolute;
z-index: 10;
}
#qdrag .qdragzone{
width: 100%;
height: 50px;
background: #ccc;
line-height: 50px;
border-bottom: 2px solid #fff;
border-radius: 2px;
overflow: hidden;
} #qdrag .qdragzone img{
margin-top: 9px;
margin-left: 2%;
margin-right: 4%;
float: left;
}
#qdrag .qdragzone span{
display: inline-block;
font-weight: bold;
font-size: 14px;
float: left;
width: 20%;
color: #339966;
font-family: "Times New Roman", Times, serif;
/*font-family:Arial,Helvetica,sans-serif;font-size:100%;*/
}
#qdrag .qdragzone progress{
border-radius: 6px;
height: 12px;
width: 250px;
color: #5cb85c;
background:#fff;
}
progress::-moz-progress-bar { background: #fff;border-radius: 6px; }
progress::-webkit-progress-bar { background: #fff;border-radius: 6px;} progress::-webkit-progress-value {background-color:#5cb85c;border-radius: 6px;}
progress::-moz-progress-value { background-color:#5cb85c;border-radius: 6px;}
}
</style>
</head>
<body> <div id="qdrag">
<input type="file" id="qdrag-hidden" name="image" value=""></input>
<div class="qdragzone">
<img src="./public/upload.png">
<span>Name:test.txt</span>
<span>Size:00000 Byte</span>
<progress value="0.2" max="1">
</div>
</div>
<script type="text/javascript">
var qdrag = document.getElementById('qdrag');
var qdrag_hidden = document.getElementById('qdrag-hidden');
qdrag.onclick = function () { qdrag_hidden.click();}
qdrag_hidden.onchange = function () {
// body...
var fileList = this.files;
for (var i = 0; i < fileList.length; i++) {
sendFileByXHR('./upload.html',fileList[i]);
}
} function sendFileByXHR(url,fielObj) {
// body...
var xhr = new XMLHttpRequest();
var newprogress = createTagsEle(fielObj).newprogress;
xhr.upload.onprogress = function (event) {
// body...
console.log('xhr-loaded:'+event.loaded);
newprogress.setAttribute('value',event.loaded/event.total);
}
xhr.onreadystatechange = function () {
// body...
if (xhr.status === 200 && xhr.readyState === 4) {
console.log(xhr.responseText);
}
}
xhr.onabort = function (event) {
// body...
console.log('abort');
}
xhr.onerror = function (event) {
// body...
console.log('error');
}
var data = new FormData();
data.append(fielObj.name,fielObj);
xhr.open('POST',url,true);
xhr.send(data); }
function createTagsEle(fileObj) {
// body...
//create
var fragment = document.createDocumentFragment();
var newdiv = document.createElement('div');
var newimg = document.createElement('img');
var newspanName = document.createElement('span');
var newspanSize = document.createElement('span');
var newprogress = document.createElement('progress'); //set attribute
newdiv.setAttribute('class','qdragzone');
newimg.setAttribute('src','./public/upload.png')
newspanName.innerHTML = 'Name: ' + fileObj.name;
newspanSize.innerHTML = 'Size: ' + fileObj.size+' Byte';
newprogress.setAttribute('value',0);
newprogress.setAttribute('max',1); //append
fragment.appendChild(newdiv);
newdiv.appendChild(newimg);
newdiv.appendChild(newspanName);
newdiv.appendChild(newspanSize);
newdiv.appendChild(newprogress); // append to DOM
qdrag.appendChild(fragment);
return {newprogress};
} qdrag.addEventListener('dragover',function (event) {
// body...
event.preventDefault();
});
qdrag.addEventListener('dragenter',function (event) {
// body...
event.preventDefault();
});
qdrag.addEventListener('drop',function (event) {
// body...
event.preventDefault();
var fileList = Array.from(event.dataTransfer.files);
for (var i = 0; i < fileList.length; i++) {
sendFileByXHR('./upload.html',fileList[i]);
}
}); </script>
</body>
</html>
后端代码：
var http = require('http');
var fs = require('fs')
const PORT = 44444;
const MIME = {
default:'text/plain',
html:'text/html',
css:'text/css',
js:'text/javascript',
png:'image/png',
jpg:'image/jpg',
jpeg:'image/jpeg',
json:'application/json',
from:'multipart/form-data'
}
function handleStaticResource(req,res) {
// body...
var param = req.url.replace('/public','');
var staticResource = fs.readFileSync('.'+param,'utf8');
var fileType = req.url.split('/').pop().split('.').pop();
switch(true){
case ['js','css'].includes(fileType):
res.setHeader('Content-Type',MIME[fileType]);
break;
case ['png','jpg','jpeg'].includes(fileType):
staticResource = new Buffer(fs.readFileSync('.'+param,'base64'),'base64');
console.log(fileType);
res.setHeader('Content-Type',MIME[fileType]);
break;
default :
res.setHeader('Content-Type',MIME['default']);
console.log(MIME['default']);
break;
}
res.end(staticResource);
}
var router = function (req,res) {
// body...
res.render = function (path,options) {
// body...
var content_html = fs.readFileSync(path,'utf8');
res.writeHead(200,{'Content-Type':MIME['html']});
res.end(new Buffer(content_html,'utf8'));
}
switch(true){
case /^\/public\/([\s\S]*)/.test(req.url):
handleStaticResource(req,res);
break;
case req.url === '/':
// console.log(req.url);
res.render('./testdrag.html');
break;
case req.url === '/upload.html':
// console.log(req.headers);
var buffers = [];
req.on('data',function (chunk) {
// body...
buffers.push(chunk);
})
req.on('end',function () {
// body...
var data = Buffer.concat(buffers).toString();
res.end("ok");//正确的调用位置
})
// res.end('currSize:' + buffers.length +' '+ (new Date()).toGMTString());//错误的调用位置
break;
default:
// console.log(req.url);
res.end();
};
}
var server = http.createServer(router);
server.listen(PORT,function () {
// body...
console.log(`the server is linstening on port ${PORT}`);
})
效果：
