Java tutorial
/* * Copyright (C) 2017 Vincent Breitmoser <v.breitmoser@mugenguild.com> * * This program is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation, either version 3 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program. If not, see <http://www.gnu.org/licenses/>. */ package org.sufficientlysecure.keychain.ui.keyview.loader; import java.util.Date; import android.content.ContentResolver; import android.content.Context; import android.database.Cursor; import android.support.v4.content.AsyncTaskLoader; import android.util.Log; import org.sufficientlysecure.keychain.Constants; import org.sufficientlysecure.keychain.provider.KeychainContract.KeyRings; import org.sufficientlysecure.keychain.provider.KeychainContract.UpdatedKeys; import org.sufficientlysecure.keychain.ui.keyview.loader.KeyserverStatusLoader.KeyserverStatus; public class KeyserverStatusLoader extends AsyncTaskLoader<KeyserverStatus> { public static final String[] PROJECTION = new String[] { UpdatedKeys.LAST_UPDATED, UpdatedKeys.SEEN_ON_KEYSERVERS }; private static final int INDEX_LAST_UPDATED = 0; private static final int INDEX_SEEN_ON_KEYSERVERS = 1; private final ContentResolver contentResolver; private final long masterKeyId; private KeyserverStatus cachedResult; private ForceLoadContentObserver keyserverStatusObserver; public KeyserverStatusLoader(Context context, ContentResolver contentResolver, long masterKeyId) { super(context); this.contentResolver = contentResolver; this.masterKeyId = masterKeyId; this.keyserverStatusObserver = new ForceLoadContentObserver(); } @Override public KeyserverStatus loadInBackground() { Cursor cursor = contentResolver.query(UpdatedKeys.CONTENT_URI, PROJECTION, UpdatedKeys.MASTER_KEY_ID + " = ?", new String[] { Long.toString(masterKeyId) }, null); if (cursor == null) { Log.e(Constants.TAG, "Error loading key items!"); return null; } try { if (cursor.moveToFirst()) { if (cursor.isNull(INDEX_SEEN_ON_KEYSERVERS) || cursor.isNull(INDEX_LAST_UPDATED)) { return new KeyserverStatus(masterKeyId); } boolean isPublished = cursor.getInt(INDEX_SEEN_ON_KEYSERVERS) != 0; Date lastUpdated = new Date(cursor.getLong(INDEX_LAST_UPDATED) * 1000); return new KeyserverStatus(masterKeyId, isPublished, lastUpdated); } return new KeyserverStatus(masterKeyId); } finally { cursor.close(); } } @Override public void deliverResult(KeyserverStatus keySubkeyStatus) { cachedResult = keySubkeyStatus; if (isStarted()) { super.deliverResult(keySubkeyStatus); } } @Override protected void onStartLoading() { if (cachedResult != null) { deliverResult(cachedResult); } if (takeContentChanged() || cachedResult == null) { forceLoad(); } getContext().getContentResolver().registerContentObserver(KeyRings.buildGenericKeyRingUri(masterKeyId), true, keyserverStatusObserver); } @Override protected void onAbandon() { super.onAbandon(); getContext().getContentResolver().unregisterContentObserver(keyserverStatusObserver); } public static class KeyserverStatus { private final long masterKeyId; private final boolean isPublished; private final Date lastUpdated; KeyserverStatus(long masterKeyId, boolean isPublished, Date lastUpdated) { this.masterKeyId = masterKeyId; this.isPublished = isPublished; this.lastUpdated = lastUpdated; } KeyserverStatus(long masterKeyId) { this.masterKeyId = masterKeyId; this.isPublished = false; this.lastUpdated = null; } long getMasterKeyId() { return masterKeyId; } public boolean hasBeenUpdated() { return lastUpdated != null; } public boolean isPublished() { if (lastUpdated == null) { throw new IllegalStateException("Cannot get publication state if key has never been updated!"); } return isPublished; } public Date getLastUpdated() { return lastUpdated; } } }