上传 multipart/form-data 随机通过和失败

Question

我使用以下代码将 multipart/form-data 上传到服务器：

<!DOCTYPE html>
    <html>
    <body>
    <form >
       <input  id="file" type="file" name="file" multiple><br>
    </form>
    <button id="ajax_submit">ajax_submit</button>
    <script src="https://code.jquery.com/jquery-3.2.1.min.js" integrity="sha256-hwg4gsxgFZhOsEEamdOYGBf13FyQuiTwlAQgxVSNgt4=" crossorigin="anonymous"></script>

    <script>
    $( "#ajax_submit" ).click(function()
    {
      //alert( "Handler for .click() called." );
      var i = 0;
      while (i < document.getElementById('file').files.length)
      {

        var data = new FormData();


    //alert("before" + i);
        data.append('file', document.getElementById('file').files[i]);//first string parameter indicate the input field to name for server side
    //alert("after" + i);

        jQuery.ajax({
          url: 'http://xx.xxx.xx.xxx:8080/sign',
          data: data,
          cache: false,
          contentType: false,
          processData: false,
          method: 'POST',
          type: 'POST', // For jQuery < 1.9
          success: function(data)
          {
            //alert(data);
          }
        });
        i++;
      }
    });
    </script>
    </body>
    </html>

问题是当 select 一次有多个文件时，获得成功响应的概率非常低，而当我 select 一个文件时它有更高的概率。

当它成功时，我在Chrome上得到了请求和响应headers：

Genaral
    Request URL:http://xx.xxx.xx.xxx:8080/sign
    Request Method:POST
    Status Code:200 
    Remote Address:xx.xxx.xx.xxx:8080
    Referrer Policy:no-referrer-when-downgrade
Response Headers
    Date:Thu, 19 Oct 2017 08:50:08 GMT
    Transfer-Encoding:chunked
    X-Application-Context:application
Request Headers
    Accept:*/*
    Accept-Encoding:gzip, deflate
    Accept-Language:en-US,en;q=0.8
    Connection:keep-alive
    Content-Length:33274
    Content-Type:multipart/form-data; boundary=----WebKitFormBoundaryOuscIdBAA52VbAZK
    Host:xx.xxx.xx.xxx:8080
    Origin:null
    User-Agent:Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/61.0.3163.100 Safari/537.36
 Request Payload
    ------WebKitFormBoundaryOuscIdBAA52VbAZK
    Content-Disposition: form-data; name="file"; filename="text.pdf"
    Content-Type: application/pdf

当我失败时，我得到了以下错误消息、请求和响应headers 在 Safari 和 Chrome 浏览器上：

Chrome:

Genaral    
    Request URL:http://xx.xxx.xx.xxx:8080/sign
    Referrer Policy:no-referrer-when-downgrade
Request Headers
    Provisional headers are shown
    Accept:*/*
    Content-Type:multipart/form-data; boundary=----WebKitFormBoundaryAmGAPOT6r0Voe5mr
    Origin:null
    User-Agent:Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/61.0.3163.100 Safari/537.36
Request Payload
    ------WebKitFormBoundaryAmGAPOT6r0Voe5mr
    Content-Disposition: form-data; name="file"; filename="empty.pdf"
    Content-Type: application/pdf

POST http://xx.xxx.xx.xxx:8080/sign net::ERR_CONNECTION_REFUSED send @ jquery-3.2.1.min.js:4 ajax @ jquery-3.2.1.min.js:4 (anonymous) @ multiplefileHandler.html:26 dispatch @ jquery-3.2.1.min.js:3 q.handle @ jquery-3.2.1.min.js:4

POST http://xx.xxx.xx.xxx:8080/sign net::ERR_CONNECTION_RESET send @ jquery-3.2.1.min.js:4 ajax @ jquery-3.2.1.min.js:4 (anonymous) @ multiplefileHandler.html:26 dispatch @ jquery-3.2.1.min.js:3 q.handle @ jquery-3.2.1.min.js:3

野生动物园：

Failed to load resource: The network connection was lost.

Failed to load resource: Could not connect to the server.

当我尝试使用 Java Apache HTTP 客户端进行调用时，出现以下错误：

org.apache.http.NoHttpResponseException: xx.xxx.xx.xxx:8080 failed to respond

当我 select 8 个文件并使用 Chrome 按下 ajax_submit 按钮时，activity 监视器的屏幕截图。当时Chrome只有一个tab上面的页面。

Answer 1

当几毫秒内有很多请求时，服务器会失败，服务器端没有人响应。

总结：服务器端故障。

上传 multipart/form-data 随机通过和失败

Uploading multipart/form-data is pass and fail randomly

javascript

ajax

apache-httpclient-4.x