如何下载然后上传文件？

Tried to use the following code, but it doesn't work properly:

试图使用以下代码,但它无法正常工作:

  // download the file first
  var req = new XMLHttpRequest();
  req.open('GET', url, false);
  req.overrideMimeType('text/plain; charset=x-user-defined');
  req.send(null);
  if (req.status != 200) return '';

  // upload the file
  req.open("POST", "http://mysite.com/upload", false);
  req.setRequestHeader("Content-Length", req.responseText.length);
  req.sendAsBinary(req.responseText); // What should I pass here?

  if (req.status != 200) return '';
  return req.responseText;

sendAsBinary is firefox function.

sendAsBinary是firefox函数。

Upd. Also I've tried to upload that as part of the form:

UPD。我也尝试将其作为表单的一部分上传:

var response = req.responseText;
var formData = new FormData();
formData.append("file", response);
req.open("POST", "http://mysite.com/upload", false);
req.send(formData);

But still not full data is received by the server.

但是服务器仍然没有收到完整的数据。

2 个解决方案

#1

Finally I've used the approach with temp file:

最后我用temp文件的方法:

  var downloadCompleted = false;

  // download the file first
  var persist = Components.classes["@mozilla.org/embedding/browser/nsWebBrowserPersist;1"]
                  .createInstance(Components.interfaces.nsIWebBrowserPersist);
  // get OS temp folder
  var file = Components.classes["@mozilla.org/file/directory_service;1"]
                .getService(Components.interfaces.nsIProperties)
                .get("TmpD", Components.interfaces.nsIFile);
  file.append("temp.ext");
  file.createUnique(Components.interfaces.nsIFile.NORMAL_FILE_TYPE, 0666);

  var fURI = Services.io.newURI(url,null,null);
    const nsIWBP = Components.interfaces.nsIWebBrowserPersist;
    const flags = nsIWBP.PERSIST_FLAGS_REPLACE_EXISTING_FILES;
    persist.persistFlags = flags | nsIWBP.PERSIST_FLAGS_FROM_CACHE;

  persist.progressListener = {
    onProgressChange: function(aWebProgress, aRequest, aCurSelfProgress, aMaxSelfProgress, aCurTotalProgress, aMaxTotalProgress) {
      },
    onStateChange: function(aWebProgress, aRequest, aStateFlags, aStatus) {
      if (aStateFlags & Components.interfaces.nsIWebProgressListener.STATE_STOP) {
         downloadCompleted = true; // file has been downloaded        
      }
    }
  }
  persist.saveURI(fURI, null, null, null, "", file);  

  var thread = Components.classes["@mozilla.org/thread-manager;1"]
                        .getService(Components.interfaces.nsIThreadManager)
                        .currentThread;
  while (!downloadCompleted) // emulate synchronous request, not recommended approach
    thread.processNextEvent(true); 

  // upload the file
  var stream = Components.classes["@mozilla.org/network/file-input-stream;1"]
                       .createInstance(Components.interfaces.nsIFileInputStream);
  stream.init(file, 0x04 | 0x08, 0644, 0x04); // file is an nsIFile instance   

  // try to determine the MIME type of the file
  var mimeType = "text/plain";
  try {
    var mimeService = Components.classes["@mozilla.org/mime;1"]
            .getService(Components.interfaces.nsIMIMEService);
    mimeType = mimeService.getTypeFromFile(file); // file is an nsIFile instance
  }
  catch(e) { /* just use text/plain */ }

  var req = Components.classes["@mozilla.org/xmlextras/xmlhttprequest;1"]
                      .createInstance(Components.interfaces.nsIXMLHttpRequest);
  req.open('POST', "http://mysite.com/upload", false); 
  req.setRequestHeader('Content-Type', mimeType);
  req.send(stream);

  // delete the file
  file.remove(false);

#2

You need to store the responseText in an intermediate variable before reusing the req object.

在重用req对象之前,需要将responseText存储在中间变量中。

// download the file first
var req = new XMLHttpRequest();
req.open('GET', url, false);
req.overrideMimeType('text/plain; charset=x-user-defined');
req.send(null);
if (req.status != 200) return '';
var response = req.responseText;

// upload the file
req.open("POST", "http://mysite.com/upload", false);
req.setRequestHeader("Content-Length", response.length);
req.sendAsBinary(response);
if (req.status != 200) return '';
return req.responseText;

Update

Per the MDN page Using XMLHttpRequest, it looks like the above code won't work. Following is the proper way to get the binary response. In the end, you will have an array of unsigned integers which you could send back to the server and convert to binary. I think.

根据MDN页面使用XMLHttpRequest,看起来上面的代码不起作用。以下是获取二进制响应的正确方法。最后,您将拥有一组无符号整数,您可以将它们发送回服务器并转换为二进制。我认为。

//req.responseType is only defined for FF6+
req.responseType = "arraybuffer";
req.send(null);

//req.response is for FF6+, req.mozResponseArrayBuffer is for FF < 6
var buffer = req.mozResponseArrayBuffer || req.response;
if (buffer) {
  var byteArray = new Uint8Array(buffer);
}

Update 2

To submit the byteArray to a server, I would try something like the following untested, almost guaranteed not to work code.

要将byteArray提交到服务器,我会尝试类似以下未测试的内容,几乎保证不会工作代码。

req.open("POST", "http://mysite.com/upload", false);
req.setRequestHeader("Content-Length", byteArray.length);
//if this doesn't work, try byteArray.buffer
//if byteArray.buffer works, try skipping 'var byteArray = new Uint8Array(buffer);' altogether and just sending the buffer directly
req.send(byteArray);

Update 3

Could Using XMLHttpRequest from JavaScript modules / XPCOM components have anything to do with your issue?

可以从JavaScript模块/ XPCOM组件中使用XMLHttpRequest与您的问题有什么关系吗?

#1