Php 如何使用拖放功能上载多个文件；删除并浏览

我使用此代码上传文件、拖放或浏览。代码工作正常，除了，我一次只能上传一个文件

<div class="container" >
    <input type="file" name="file" id="file">

    <!-- Drag and Drop container-->
    <div class="upload-area"  id="uploadfile">
        <h1>Drag and Drop file here<br/>Or<br/>Click to select file</h1>
    </div>
</div>

ajax请求：

function uploadData(formdata){

  $.ajax({
    url: 'upload.php',
    type: 'post',
    data: formdata,
    contentType: false,
    processData: false,

    success: function(data){
        $('.echo').html(data);
    }
  });
}

php部分：

/* Getting file name */
$filename = $_FILES['file']['name'];

/* Location */
$location = "uploads/".$filename;

/* Upload file */
if(move_uploaded_file($_FILES['file']['tmp_name'],$location)){
    echo 'Uploaded: ' . $filename;
}

一次上传一个文件就可以了

如何通过拖放和浏览使其同时适用于多个上载

/* Getting file name */
$filename = $_FILES['file']['name'];

/* Location */
$location = "uploads/".$filename;

/* Upload file */
if(move_uploaded_file($_FILES['file']['tmp_name'],$location)){
    echo 'Uploaded: ' . $filename;
}