转载：http://www.zixuephp.com/phpstudy/phpshilie/20170829_43029.html
服务端为什么不能直接传大文件？跟php.ini里面的几个配置有关
upload_max_filesize = 2M //PHP最大能接受的文件大小
post_max_size = 8M //PHP能收到的最大POST值'
memory_limit = 128M //内存上限
max_execution_time = 30 //最大执行时间
当然不能简单粗暴的把上面几个值调大，否则服务器内存资源吃光是迟早的问题。
解决思路
好在HTML5开放了新的FILE API，也可以直接操作二进制对象，我们可以直接在浏览器端实现文件切割，按照以前的做法就得用Flash的方案，实现起来会麻烦很多。
JS思路
1.监听上传按钮的onchange事件
2.获取文件的FILE对象
3.把文件的FILE对象进行切割，并且附加到FORMDATA对象中
4.把FORMDATA对象通过AJAX发送到服务器
5.重复3、4步骤，直到文件发送完。
PHP思路
1.建立上传文件夹
2.把文件从上传临时目录移动到上传文件夹
3.所有的文件块上传完成后，进行文件合成
4.删除文件夹
5.返回上传后的文件路径
DEMO代码
前端部分代码
<!doctype html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport"
content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>Document</title>
<style>
#progress{
300px;
height: 20px;
background-color:#f7f7f7;
box-shadow:inset 0 1px 2px rgba(0,0,0,0.1);
border-radius:4px;
background-image:linear-gradient(to bottom,#f5f5f5,#f9f9f9);
}
#finish{
background-color: #149bdf;
background-image:linear-gradient(45deg,rgba(255,255,255,0.15) 25%,transparent 25%,transparent 50%,rgba(255,255,255,0.15) 50%,rgba(255,255,255,0.15) 75%,transparent 75%,transparent);
background-size:40px 40px;
height: 100%;
}
form{
margin-top: 50px;
}
</style>
</head>
<body>
<div id="progress">
<div id="finish" style=" 0%;" progress="0"></div>
</div>
<form action="./upload.php">
<input type="file" name="file" id="file">
<input type="button" value="停止" id="stop">
</form>
<script>
var fileForm = document.getElementById("file");
var stopBtn = document.getElementById('stop');
var upload = new Upload();
fileForm.onchange = function(){
upload.addFileAndSend(this);
}
stopBtn.onclick = function(){
this.value = "停止中";
upload.stop();
this.value = "已停止";
}
function Upload(){
var xhr = new XMLHttpRequest();
var form_data = new FormData();
const LENGTH = 1024 * 1024;
var start = 0;
var end = start + LENGTH;
var blob;
var blob_num = 1;
var is_stop = 0
//对外方法，传入文件对象
this.addFileAndSend = function(that){
var file = that.files[0];
blob = cutFile(file);
sendFile(blob,file);
blob_num += 1;
}
//停止文件上传
this.stop = function(){
xhr.abort();
is_stop = 1;
}
//切割文件
function cutFile(file){
var file_blob = file.slice(start,end);
start = end;
end = start + LENGTH;
return file_blob;
};
//发送文件
function sendFile(blob,file){
var total_blob_num = Math.ceil(file.size / LENGTH);
form_data.append('file',blob);
form_data.append('blob_num',blob_num);
form_data.append('total_blob_num',total_blob_num);
form_data.append('file_name',file.name);
xhr.open('POST','./upload.php',false);
xhr.onreadystatechange = function () {
var progress;
var progressObj = document.getElementById('finish');
if(total_blob_num == 1){
progress = '100%';
}else{
progress = Math.min(100,(blob_num/total_blob_num)* 100 ) +'%'; }
progressObj.style.width = progress;
var t = setTimeout(function(){ if(start < file.size && is_stop === 0){ blob = cutFile(file); sendFile(blob,file); blob_num += 1; }else{ setTimeout(t); } },1000); } xhr.send(form_data); } }</script></body></html>
PHP部分代码
<?php
class Upload{
private $filepath = './upload'; //上传目录
private $tmpPath; //PHP文件临时目录
private $blobNum; //第几个文件块
private $totalBlobNum; //文件块总数
private $fileName; //文件名
public function __construct($tmpPath,$blobNum,$totalBlobNum,$fileName){
$this->tmpPath = $tmpPath;
$this->blobNum = $blobNum;
$this->totalBlobNum = $totalBlobNum;
$this->fileName = $fileName;
$this->moveFile();
$this->fileMerge();
}
//判断是否是最后一块，如果是则进行文件合成并且删除文件块
private function fileMerge(){
if($this->blobNum == $this->totalBlobNum){
$blob = '';
for($i=1; $i<= $this->totalBlobNum; $i++){
$blob .= file_get_contents($this->filepath.'/'. $this->fileName.'__'.$i);
}
file_put_contents($this->filepath.'/'. $this->fileName,$blob);
$this->deleteFileBlob();
}
}
//删除文件块
private function deleteFileBlob(){
for($i=1; $i<= $this->totalBlobNum; $i++){
@unlink($this->filepath.'/'. $this->fileName.'__'.$i);
}
}
//移动文件
private function moveFile(){
$this->touchDir();
$filename = $this->filepath.'/'. $this->fileName.'__'.$this->blobNum;
move_uploaded_file($this->tmpPath,$filename);
}
//API返回数据
public function apiReturn(){
if($this->blobNum == $this->totalBlobNum){
if(file_exists($this->filepath.'/'. $this->fileName)){
$data['code'] = 2;
$data['msg'] = 'success';
$data['file_path'] = 'http://'.$_SERVER['HTTP_HOST'].dirname($_SERVER['DOCUMENT_URI']).str_replace('.','',$this->filepath).'/'. $this->fileName;
}
}else{
if(file_exists($this->filepath.'/'. $this->fileName.'__'.$this->blobNum)){
$data['code'] = 1;
$data['msg'] = 'waiting for all';
$data['file_path'] = '';
}
}
header('Content-type: application/json');
echo json_encode($data);
}
//建立上传文件夹
private function touchDir(){
if(!file_exists($this->filepath)){
return mkdir($this->filepath);
}
}
}
//实例化并获取系统变量传参
$upload = new Upload($_FILES['file']['tmp_name'],$_POST['blob_num'],$_POST['total_blob_num'],$_POST['file_name']);
//调用方法，返回结果
$upload->apiReturn();