/
TypedNotificationCallback.java
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/
TypedNotificationCallback.java
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/*
* Copyright 2013 Google Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
* in compliance with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software distributed under the License
* is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
* or implied. See the License for the specific language governing permissions and limitations under
* the License.
*/
package com.google.api.client.googleapis.notifications;
import com.google.api.client.http.HttpMediaType;
import com.google.api.client.util.Beta;
import com.google.api.client.util.ObjectParser;
import com.google.api.client.util.Preconditions;
import java.io.IOException;
import java.nio.charset.Charset;
/**
* {@link Beta} <br>
* Callback to receive notifications for watched resource in which the . Callback which is used to
* receive typed {@link AbstractNotification}s after subscribing to a topic.
*
* <p>Must NOT be implemented in form of an anonymous class as this will break serialization.
*
* <p>Implementation should be thread-safe. <b>Example usage:</b>
*
* <pre>
* static class MyNotificationCallback
* extends JsonNotificationCallback{@literal <}ListResponse{@literal >} {
*
* private static final long serialVersionUID = 1L;
*
* {@literal @}Override
* protected void onNotification(
* StoredChannel subscription, Notification notification, ListResponse content) {
* switch (notification.getResourceState()) {
* case ResourceStates.SYNC:
* break;
* case ResourceStates.EXISTS:
* break;
* case ResourceStates.NOT_EXISTS:
* break;
* }
* }
*
* {@literal @}Override
* protected ObjectParser getObjectParser(Notification notification) throws IOException {
* return new JsonObjectParser(new GsonFactory());
* }
*
* {@literal @}Override
* protected Class{@literal <}ListResponse{@literal >} getDataClass() throws IOException {
* return ListResponse.class;
* }
* }
* </pre>
*
* @param <T> Java type of the notification content
* @author Yaniv Inbar
* @author Matthias Linder (mlinder)
* @since 1.16
*/
@Beta
public abstract class TypedNotificationCallback<T> implements UnparsedNotificationCallback {
private static final long serialVersionUID = 1L;
/**
* Handles a received typed notification.
*
* @param storedChannel stored notification channel
* @param notification typed notification
*/
protected abstract void onNotification(
StoredChannel storedChannel, TypedNotification<T> notification) throws IOException;
/** Returns an {@link ObjectParser} which can be used to parse this notification. */
protected abstract ObjectParser getObjectParser() throws IOException;
/**
* Returns the data class to parse the notification content into or {@code Void.class} if no
* notification content is expected.
*/
protected abstract Class<T> getDataClass() throws IOException;
public final void onNotification(StoredChannel storedChannel, UnparsedNotification notification)
throws IOException {
TypedNotification<T> typedNotification = new TypedNotification<T>(notification);
// TODO(yanivi): how to properly detect if there is no content?
String contentType = notification.getContentType();
if (contentType != null) {
Charset charset = new HttpMediaType(contentType).getCharsetParameter();
Class<T> dataClass = Preconditions.checkNotNull(getDataClass());
typedNotification.setContent(
getObjectParser().parseAndClose(notification.getContentStream(), charset, dataClass));
}
onNotification(storedChannel, typedNotification);
}
}