javascript – 如何下载然后上传文件？

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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是firefox function.

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);

但是服务器仍然没有收到完整的数据.

解决方法:

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);

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