import com.google.api.client.http.EmptyContent; //导入依赖的package包/类
/**
 * {@link Beta} <br/>
 * The call back method that will be invoked on a server error or an I/O
 * exception during resumable upload inside {@link #upload}.
 *
 * <p>
 * This method changes the current request to query the current status of
 * the upload to find how many bytes were successfully uploaded before the
 * server error occurred.
 * </p>
 */
@Beta
void serverErrorCallback() throws IOException {
	Preconditions.checkNotNull(currentRequest,
			"The current request should not be null");

	// Query the current status of the upload by issuing an empty PUT
	// request on the upload URI.
	currentRequest.setContent(new EmptyContent());
	currentRequest
			.getHeaders()
			.setContentRange(
					"bytes */"
							+ (isMediaLengthKnown() ? getMediaContentLength()
									: "*"));
}
 

import com.google.api.client.http.EmptyContent; //导入依赖的package包/类
public static boolean addChildToGroup(HttpRequestFactory pHttpRequestFactory, AlfrescoConfig pConfig,
        String pStrGroupId, String pStrChildId) {
	mLog.debug("START addChildToGroup(String, String)");

	boolean lRet = false;

	GroupsUrl lUrl = new GroupsUrl(pConfig.getHost());
	lUrl.addChild(pStrGroupId, pStrChildId);
	try {
		// FIXME (Alessio): bisognerebbe trasferire altrove questo codice ripetitivo
		HttpHeaders lRequestHeaders = new HttpHeaders().setContentType("application/json");
		HttpRequest lRequest =
		        pHttpRequestFactory.buildPostRequest(lUrl, new EmptyContent()).setHeaders(lRequestHeaders);

		// TODO (Alessio): la risposta è completamente ignorata! Vanno gestiti i diversi casi
		// possibili.
		// L'implementazione dovrebbe prima controllare se l'utente è già parte del gruppo,
		// quindi eventualmente effettuare l'aggiunta.
		int lStatusCode = lRequest.execute().getStatusCode();
		if (200 <= lStatusCode && lStatusCode < 300) {
			lRet = true;
		}

	} catch (Exception e) {
		// TODO (Alessio): gestione decente delle eccezioni
		// mLog.error("Unexpected failure", e);
		lRet = false;
	}

	mLog.debug("END addChildToGroup(String, String)");
	return lRet;
}
 

import com.google.api.client.http.EmptyContent; //导入依赖的package包/类
/**
 * This method sends a POST request with empty content to get the unique
 * upload URL.
 *
 * @param initiationRequestUrl
 *            The request URL where the initiation request will be sent
 */
private HttpResponse executeUploadInitiation(GenericUrl initiationRequestUrl)
		throws IOException {
	updateStateAndNotifyListener(UploadState.INITIATION_STARTED);

	initiationRequestUrl.put("uploadType", "resumable");
	HttpContent content = metadata == null ? new EmptyContent() : metadata;
	HttpRequest request = requestFactory.buildRequest(
			initiationRequestMethod, initiationRequestUrl, content);
	initiationHeaders.set(CONTENT_TYPE_HEADER, mediaContent.getType());
	if (isMediaLengthKnown()) {
		initiationHeaders.set(CONTENT_LENGTH_HEADER,
				getMediaContentLength());
	}
	request.getHeaders().putAll(initiationHeaders);
	HttpResponse response = executeCurrentRequest(request);
	boolean notificationCompleted = false;

	try {
		updateStateAndNotifyListener(UploadState.INITIATION_COMPLETE);
		notificationCompleted = true;
	} finally {
		if (!notificationCompleted) {
			response.disconnect();
		}
	}
	return response;
}
 

import com.google.api.client.http.EmptyContent; //导入依赖的package包/类
/**
 * Executes the current request with some common code that includes
 * exponential backoff and GZip encoding.
 *
 * @param request
 *            current request
 * @return HTTP response
 */
private HttpResponse executeCurrentRequest(HttpRequest request)
		throws IOException {
	// enable GZip encoding if necessary
	if (!disableGZipContent
			&& !(request.getContent() instanceof EmptyContent)) {
		request.setEncoding(new GZipEncoding());
	}
	// execute request
	HttpResponse response = executeCurrentRequestWithoutGZip(request);
	return response;
}
 

import com.google.api.client.http.EmptyContent; //导入依赖的package包/类
private HttpRequest buildHttpRequest() throws IOException {
	final HttpRequest httpRequest = getGracenote().getRequestFactory().buildRequest(HttpMethods.POST, buildHttpRequestUrl(), httpContent);
	httpRequest.setParser(getGracenote().getObjectParser());
	
	if (httpContent == null) {
		httpRequest.setContent(new EmptyContent());
	}
	
	return httpRequest;
}
 

import com.google.api.client.http.EmptyContent; //导入依赖的package包/类
/**
 * Initiates the resumable upload by sending a request to Google Cloud Storage.
 *
 * @param batchJobUploadUrl the {@code uploadUrl} of a {@code BatchJob}
 * @return the URI for the initiated resumable upload
 */
private URI initiateResumableUpload(URI batchJobUploadUrl) throws BatchJobException {
  // This follows the Google Cloud Storage guidelines for initiating resumable uploads:
  // https://cloud.google.com/storage/docs/resumable-uploads-xml
  HttpRequestFactory requestFactory =
      httpTransport.createRequestFactory(new HttpRequestInitializer() {
        @Override
        public void initialize(HttpRequest request) throws IOException {
          HttpHeaders headers = createHttpHeaders();
          headers.setContentLength(0L);
          headers.set("x-goog-resumable", "start");
          request.setHeaders(headers);
          request.setLoggingEnabled(true);
        }
      });

  try {
    HttpRequest httpRequest =
        requestFactory.buildPostRequest(new GenericUrl(batchJobUploadUrl), new EmptyContent());
    HttpResponse response = httpRequest.execute();
    if (response.getHeaders() == null || response.getHeaders().getLocation() == null) {
      throw new BatchJobException(
          "Initiate upload failed. Resumable upload URI was not in the response.");
    }
    return URI.create(response.getHeaders().getLocation());
  } catch (IOException e) {
    throw new BatchJobException("Failed to initiate upload", e);
  }
}