使用XMLHttpRequest上传AJAX文件

Question

I know there are a lot of similar questions, but I still haven't found a solution for my problem. I'm trying to upload a file with XMLHttpRequest, so I developed the code below:

var sendFiles = function(url,onload,onerror,file,headers){
    var xhr = XMLHttpRequest ? new XMLHttpRequest() : new ActiveXObject('Microsoft.XMLHttp'),
    upload = xhr.upload;
    API.addEvent(xhr,'readystatechange',function(){
        if(xhr.readyState==4)
            if((xhr.status>=200 && xhr.status<300) || xhr.status==304){
                this.response = this.response || this.responseText;
                onload.call(xhr);
            }else onerror.call(xhr);
    });
    xhr.open('POST',url,true);
    for(var n=0;n<headers.length;n++)
        xhr.setRequestHeader(headers[n]);
    xhr.send(file);
    return xhr;
};

And the PHP-side script is:

<?php
header('Content-type: text/html;charset=ISO-8859-1');
$status = 0;
if(@copy($_FILES['file']['tmp_name'],'test\\' . $_FILES['file']['name']))
    $status = 1;
else
    $err = '0';
echo '{
    "status": ' . $status . '
}';
?>;

But the var $_FILES['file'] seems to be empty, which means that the file isn't being sent to the server. Then i decided to use the FormData Object, in the code below

var sendFiles = function(url,onload,onerror,file,headers){
    var xhr = XMLHttpRequest ? new XMLHttpRequest() : new    ActiveXObject('Microsoft.XMLHttp'),
    upload = xhr.upload,
    formData = new FormData();
    formData.append('file',file);
    API.addEvent(xhr,'readystatechange',function(){
        if(xhr.readyState==4)
            if((xhr.status>=200 && xhr.status<300) || xhr.status==304){
                this.response = this.response || this.responseText;
                onload.call(xhr);
            }else onerror.call(xhr);
    });
    xhr.open('POST',url,true);
    for(var n=0;n<headers.length;n++)
        xhr.setRequestHeader(headers[n]);
    xhr.send(formData);
    return xhr;
};

And it worked, but only with file sizes low to about 8mb. When I try sending a file that has more than 8mb of size, the var $_FILES['file'] becomes empty again

NOTE: the 'file' var corresponds to something like document.getElementsById('fileInput').files[0];

Answer 1

To avoid the post_max_size limitation problem... but also out of memory problems on both sides :

On the client side

• use PUT instead of POST :

  xhr.open("put", "upload.php", true);

• add custom headers to specify original FileName and FileSize :

  xhr.setRequestHeader("X-File-Name", file.name);
xhr.setRequestHeader("X-File-Size", file.size);

• use the File object directly in your XHR send method :

  xhr.send(file);

  Please note that the File object can be obtained directly via the “files” property of your input[type=file] DOM object

On the server side

• read the custom headers via $_SERVER :

  $filename = $_SERVER['HTTP_X_FILE_NAME'];
$filesize = $_SERVER['HTTP_X_FILE_SIZE'];

• read file data using php://input :

  $in = fopen('php://input','r');

You'll then be able to send very big files (1GB or more) without any limitation!!!

This code works for FireFox 4+, Chrome 6+, IE10+

Answer 2

更改ini文件中的post_max_size指令

Answer 3

The Ajax call will not limit the size. It is probably the max file size in the php ini file.