Java tutorial
/******************************************************************************* * Copyright (c) 2012-2016 Codenvy, S.A. * All rights reserved. This program and the accompanying materials * are made available under the terms of the Eclipse Public License v1.0 * which accompanies this distribution, and is available at * http://www.eclipse.org/legal/epl-v10.html * * Contributors: * Codenvy, S.A. - initial API and implementation *******************************************************************************/ package org.eclipse.che.ide.rest; import com.google.gwt.http.client.Request; import com.google.gwt.http.client.RequestCallback; import com.google.gwt.http.client.Response; import com.google.gwt.user.client.Window; import org.eclipse.che.ide.commons.exception.ServerDisconnectedException; import org.eclipse.che.ide.commons.exception.ServerException; import org.eclipse.che.ide.commons.exception.UnauthorizedException; import static org.eclipse.che.ide.MimeType.APPLICATION_JSON; import static org.eclipse.che.ide.rest.HTTPHeader.CONTENT_TYPE; /** * Callback class for receiving the {@link Response}. * * @param <T> * the return type of the response the callback expects. * Use {@link Void} for methods returning {@code void}. * * @author Valeriy Svydenko */ public abstract class AsyncRequestCallback<T> implements RequestCallback { // HTTP code 207 is "Multi-Status" // IE misinterpreting HTTP status code 204 as 1223 (http://www.mail-archive.com/jquery-en@googlegroups.com/msg13093.html) private static final int[] DEFAULT_SUCCESS_CODES = { Response.SC_OK, Response.SC_CREATED, Response.SC_NO_CONTENT, 207, 1223 }; private final Unmarshallable<T> unmarshaller; private int[] successCodes; private AsyncRequestLoader loader; private T payload; private AsyncRequest request; public AsyncRequestCallback() { this(null); } /** * Constructor retrieves unmarshaller with initialized (this is important!) object. * When response comes callback calls {@link Unmarshallable#unmarshal(com.google.gwt.http.client.Response)} * which populates the object. * * @param unmarshaller */ public AsyncRequestCallback(Unmarshallable<T> unmarshaller) { this.successCodes = DEFAULT_SUCCESS_CODES; this.unmarshaller = unmarshaller; } /** @return the result */ public T getPayload() { return payload; } /** * @param successCodes * the successCodes to set */ public void setSuccessCodes(int[] successCodes) { this.successCodes = successCodes; } public final void setLoader(AsyncRequestLoader loader) { this.loader = loader; } /** @see com.google.gwt.http.client.RequestCallback#onError(com.google.gwt.http.client.Request, java.lang.Throwable) */ @Override public final void onError(Request request, Throwable exception) { if (loader != null) { loader.hide(); } onFailure(exception); } /** * @see com.google.gwt.http.client.RequestCallback#onResponseReceived(com.google.gwt.http.client.Request, * com.google.gwt.http.client.Response) */ @Override public final void onResponseReceived(Request request, Response response) { if (loader != null) { loader.hide(); } // If there is no connection to the server then status equals 0 ( In Internet Explorer status is 12029 ) if (response.getStatusCode() == 0 || response.getStatusCode() == 12029) { onServerDisconnected(); return; } if (response.getStatusCode() == HTTPStatus.UNAUTHORIZED) { onUnauthorized(response); return; } if (isSuccessful(response)) { handleSuccess(response); } else { handleFailure(response); } } private void handleFailure(Response response) { Exception exception; String contentType = response.getHeader(CONTENT_TYPE); if (contentType != null && !contentType.contains(APPLICATION_JSON)) { String message = generateErrorMessage(response); exception = new Exception(message); } else { exception = new ServerException(response); } onFailure(exception); } private void handleSuccess(Response response) { try { if (unmarshaller != null) { //It's needed for handling a situation when response DTO object is NULL if (response.getStatusCode() != Response.SC_NO_CONTENT) { unmarshaller.unmarshal(response); } payload = unmarshaller.getPayload(); } onSuccess(payload); } catch (Exception e) { onFailure(e); } } private String generateErrorMessage(Response response) { StringBuilder message = new StringBuilder(); String protocol = Window.Location.getProtocol(); String host = Window.Location.getHost(); String url = this.request.getRequestBuilder().getUrl(); //deletes query params url = url.substring(0, url.indexOf('?')); message.append(response.getStatusCode()).append(" ").append(response.getStatusText()).append(" ") .append(protocol).append("//").append(host).append(url); return message.toString(); } protected final boolean isSuccessful(Response response) { if (successCodes == null) { successCodes = DEFAULT_SUCCESS_CODES; } if ("Authentication-required".equals(response.getHeader(HTTPHeader.JAXRS_BODY_PROVIDED))) { return false; } for (int code : successCodes) { if (response.getStatusCode() == code) { return true; } } return false; } /** * If response is successfully received and response status code is in set of success codes. * * @param result * the response returned from the request. Will be {@code null} if * {@code unmarshaller} wasn't set */ protected abstract void onSuccess(T result); /** * Called when an error received from the server or when request was failed. * * @param exception * the exception thrown */ protected abstract void onFailure(Throwable exception); /** If server disconnected. */ protected void onServerDisconnected() { onFailure(new ServerDisconnectedException(request)); } /** * If unauthorized. * * @param response */ protected void onUnauthorized(Response response) { onFailure(new UnauthorizedException(response, request)); } public AsyncRequest getRequest() { return request; } public void setRequest(AsyncRequest request) { this.request = request; } }