Java tutorial
/* * Copyright 2011-2015 the original author or authors. * * 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 de.schildbach.wallet; import static com.google.common.base.Preconditions.checkNotNull; import java.net.MalformedURLException; import java.net.URL; import java.util.Currency; import java.util.Iterator; import java.util.Locale; import java.util.Map; import java.util.TreeMap; import javax.annotation.Nullable; import org.bitcoinj.core.Coin; import org.bitcoinj.utils.Fiat; import org.bitcoinj.utils.MonetaryFormat; import org.json.JSONObject; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import com.google.common.base.Stopwatch; import com.google.common.base.Strings; import com.squareup.okhttp.Call; import com.squareup.okhttp.Request; import com.squareup.okhttp.Response; import de.schildbach.wallet.util.GenericUtils; import android.content.ContentProvider; import android.content.ContentValues; import android.content.Context; import android.database.Cursor; import android.database.MatrixCursor; import android.net.Uri; import android.preference.PreferenceManager; import android.provider.BaseColumns; import android.text.format.DateUtils; /** * @author Andreas Schildbach */ public class ExchangeRatesProvider extends ContentProvider { public static class ExchangeRate { public ExchangeRate(final org.bitcoinj.utils.ExchangeRate rate, final String source) { checkNotNull(rate.fiat.currencyCode); this.rate = rate; this.source = source; } public final org.bitcoinj.utils.ExchangeRate rate; public final String source; public String getCurrencyCode() { return rate.fiat.currencyCode; } @Override public String toString() { return getClass().getSimpleName() + '[' + rate.fiat + ']'; } } public static final String KEY_CURRENCY_CODE = "currency_code"; private static final String KEY_RATE_COIN = "rate_coin"; private static final String KEY_RATE_FIAT = "rate_fiat"; private static final String KEY_SOURCE = "source"; public static final String QUERY_PARAM_Q = "q"; private static final String QUERY_PARAM_OFFLINE = "offline"; private Configuration config; private String userAgent; @Nullable private Map<String, ExchangeRate> exchangeRates = null; private long lastUpdated = 0; private static final URL BITCOINAVERAGE_URL; private static final String[] BITCOINAVERAGE_FIELDS = new String[] { "24h_avg", "last" }; private static final String BITCOINAVERAGE_SOURCE = "BitcoinAverage.com"; static { try { BITCOINAVERAGE_URL = new URL("https://api.bitcoinaverage.com/custom/abw"); } catch (final MalformedURLException x) { throw new RuntimeException(x); // cannot happen } } private static final long UPDATE_FREQ_MS = 10 * DateUtils.MINUTE_IN_MILLIS; private static final Logger log = LoggerFactory.getLogger(ExchangeRatesProvider.class); @Override public boolean onCreate() { final Context context = getContext(); this.config = new Configuration(PreferenceManager.getDefaultSharedPreferences(context), context.getResources()); this.userAgent = WalletApplication .httpUserAgent(WalletApplication.packageInfoFromContext(context).versionName); final ExchangeRate cachedExchangeRate = config.getCachedExchangeRate(); if (cachedExchangeRate != null) { exchangeRates = new TreeMap<String, ExchangeRate>(); exchangeRates.put(cachedExchangeRate.getCurrencyCode(), cachedExchangeRate); } return true; } public static Uri contentUri(final String packageName, final boolean offline) { final Uri.Builder uri = Uri.parse("content://" + packageName + '.' + "exchange_rates").buildUpon(); if (offline) uri.appendQueryParameter(QUERY_PARAM_OFFLINE, "1"); return uri.build(); } @Override public Cursor query(final Uri uri, final String[] projection, final String selection, final String[] selectionArgs, final String sortOrder) { final long now = System.currentTimeMillis(); final boolean offline = uri.getQueryParameter(QUERY_PARAM_OFFLINE) != null; if (!offline && (lastUpdated == 0 || now - lastUpdated > UPDATE_FREQ_MS)) { Map<String, ExchangeRate> newExchangeRates = null; if (newExchangeRates == null) newExchangeRates = requestExchangeRates(BITCOINAVERAGE_URL, userAgent, BITCOINAVERAGE_SOURCE, BITCOINAVERAGE_FIELDS); if (newExchangeRates != null) { exchangeRates = newExchangeRates; lastUpdated = now; final ExchangeRate exchangeRateToCache = bestExchangeRate(config.getExchangeCurrencyCode()); if (exchangeRateToCache != null) config.setCachedExchangeRate(exchangeRateToCache); } } if (exchangeRates == null) return null; final MatrixCursor cursor = new MatrixCursor( new String[] { BaseColumns._ID, KEY_CURRENCY_CODE, KEY_RATE_COIN, KEY_RATE_FIAT, KEY_SOURCE }); if (selection == null) { for (final Map.Entry<String, ExchangeRate> entry : exchangeRates.entrySet()) { final ExchangeRate exchangeRate = entry.getValue(); final org.bitcoinj.utils.ExchangeRate rate = exchangeRate.rate; final String currencyCode = exchangeRate.getCurrencyCode(); cursor.newRow().add(currencyCode.hashCode()).add(currencyCode).add(rate.coin.value) .add(rate.fiat.value).add(exchangeRate.source); } } else if (selection.equals(QUERY_PARAM_Q)) { final String selectionArg = selectionArgs[0].toLowerCase(Locale.US); for (final Map.Entry<String, ExchangeRate> entry : exchangeRates.entrySet()) { final ExchangeRate exchangeRate = entry.getValue(); final org.bitcoinj.utils.ExchangeRate rate = exchangeRate.rate; final String currencyCode = exchangeRate.getCurrencyCode(); final String currencySymbol = GenericUtils.currencySymbol(currencyCode); if (currencyCode.toLowerCase(Locale.US).contains(selectionArg) || currencySymbol.toLowerCase(Locale.US).contains(selectionArg)) cursor.newRow().add(currencyCode.hashCode()).add(currencyCode).add(rate.coin.value) .add(rate.fiat.value).add(exchangeRate.source); } } else if (selection.equals(KEY_CURRENCY_CODE)) { final String selectionArg = selectionArgs[0]; final ExchangeRate exchangeRate = bestExchangeRate(selectionArg); if (exchangeRate != null) { final org.bitcoinj.utils.ExchangeRate rate = exchangeRate.rate; final String currencyCode = exchangeRate.getCurrencyCode(); cursor.newRow().add(currencyCode.hashCode()).add(currencyCode).add(rate.coin.value) .add(rate.fiat.value).add(exchangeRate.source); } } return cursor; } private ExchangeRate bestExchangeRate(final String currencyCode) { ExchangeRate rate = currencyCode != null ? exchangeRates.get(currencyCode) : null; if (rate != null) return rate; final String defaultCode = defaultCurrencyCode(); rate = defaultCode != null ? exchangeRates.get(defaultCode) : null; if (rate != null) return rate; return exchangeRates.get(Constants.DEFAULT_EXCHANGE_CURRENCY); } private String defaultCurrencyCode() { try { return Currency.getInstance(Locale.getDefault()).getCurrencyCode(); } catch (final IllegalArgumentException x) { return null; } } public static ExchangeRate getExchangeRate(final Cursor cursor) { final String currencyCode = cursor .getString(cursor.getColumnIndexOrThrow(ExchangeRatesProvider.KEY_CURRENCY_CODE)); final Coin rateCoin = Coin .valueOf(cursor.getLong(cursor.getColumnIndexOrThrow(ExchangeRatesProvider.KEY_RATE_COIN))); final Fiat rateFiat = Fiat.valueOf(currencyCode, cursor.getLong(cursor.getColumnIndexOrThrow(ExchangeRatesProvider.KEY_RATE_FIAT))); final String source = cursor.getString(cursor.getColumnIndexOrThrow(ExchangeRatesProvider.KEY_SOURCE)); return new ExchangeRate(new org.bitcoinj.utils.ExchangeRate(rateCoin, rateFiat), source); } @Override public Uri insert(final Uri uri, final ContentValues values) { throw new UnsupportedOperationException(); } @Override public int update(final Uri uri, final ContentValues values, final String selection, final String[] selectionArgs) { throw new UnsupportedOperationException(); } @Override public int delete(final Uri uri, final String selection, final String[] selectionArgs) { throw new UnsupportedOperationException(); } @Override public String getType(final Uri uri) { throw new UnsupportedOperationException(); } private static Map<String, ExchangeRate> requestExchangeRates(final URL url, final String userAgent, final String source, final String... fields) { final Stopwatch watch = Stopwatch.createStarted(); final Request.Builder request = new Request.Builder(); request.url(url); request.header("User-Agent", userAgent); final Call call = Constants.HTTP_CLIENT.newCall(request.build()); try { final Response response = call.execute(); if (response.isSuccessful()) { final String content = response.body().string(); final Map<String, ExchangeRate> rates = new TreeMap<String, ExchangeRate>(); final JSONObject head = new JSONObject(content); for (final Iterator<String> i = head.keys(); i.hasNext();) { final String currencyCode = Strings.emptyToNull(i.next()); if (currencyCode != null && !"timestamp".equals(currencyCode) && !MonetaryFormat.CODE_BTC.equals(currencyCode) && !MonetaryFormat.CODE_MBTC.equals(currencyCode) && !MonetaryFormat.CODE_UBTC.equals(currencyCode)) { final JSONObject o = head.getJSONObject(currencyCode); for (final String field : fields) { final String rateStr = o.optString(field, null); if (rateStr != null) { try { final Fiat rate = Fiat.parseFiat(currencyCode, rateStr); if (rate.signum() > 0) { rates.put(currencyCode, new ExchangeRate( new org.bitcoinj.utils.ExchangeRate(rate), source)); break; } } catch (final NumberFormatException x) { log.warn("problem fetching {} exchange rate from {}: {}", currencyCode, url, x.getMessage()); } } } } } watch.stop(); log.info("fetched exchange rates from {}, {} chars, took {}", url, content.length(), watch); return rates; } else { log.warn("http status {} when fetching exchange rates from {}", response.code(), url); } } catch (final Exception x) { log.warn("problem fetching exchange rates from " + url, x); } return null; } }