php+ajax实现带进度条的上传图片功能【附demo源码下载】

<?php
if(isset($_files["fileinput"]) && $_files["fileinput"]["error"]== upload_err_ok)
{
  ############ edit settings ##############
  $uploaddirectory  = 'f:/websites/file_upload/uploads/'; //specify upload directory ends with / (slash)
  ##########################################
  /*
  note : you will run into errors or blank page if "memory_limit" or "upload_max_filesize" is set to low in "php.ini".
  open "php.ini" file, and search for "memory_limit" or "upload_max_filesize" limit
  and set them adequately, also check "post_max_size".
  */
  //check if this is an ajax request
  if (!isset($_server['http_x_requested_with'])){
    die();
  }
  //is file size is less than allowed size.
  if ($_files["fileinput"]["size"] > 5242880) {
    die("file size is too big!");
  }
  //allowed file type server side check
  switch(strtolower($_files['fileinput']['type']))
    {
      //allowed file types
      case 'image/png':
      case 'image/gif':
      case 'image/jpeg':
      case 'image/pjpeg':
      case 'text/plain':
      case 'text/html': //html file
      case 'application/x-zip-compressed':
      case 'application/pdf':
      case 'application/msword':
      case 'application/vnd.ms-excel':
      case 'video/mp4':
        break;
      default:
        die('unsupported file!'); //output error
  }
  $file_name     = strtolower($_files['fileinput']['name']);
  $file_ext      = substr($file_name, strrpos($file_name, '.')); //get file extention
  $random_number   = rand(0, 9999999999); //random number to be added to name.
  $newfilename    = $random_number.$file_ext; //new file name
  if(move_uploaded_file($_files['fileinput']['tmp_name'], $uploaddirectory.$newfilename ))
    {
    die('success! file uploaded.');
  }else{
    die('error uploading file!');
  }
}
else
{
  die('something wrong with upload! is "upload_max_filesize" set correctly?');
}