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.data; import java.math.BigDecimal; 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.squareup.okhttp.Call; import com.squareup.okhttp.HttpUrl; import com.squareup.okhttp.Request; import com.squareup.okhttp.Response; import de.schildbach.wallet.Configuration; import de.schildbach.wallet.Constants; import de.schildbach.wallet.WalletApplication; 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 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 HttpUrl BITCOINAVERAGE_URL = HttpUrl .parse("https://apiv2.bitcoinaverage.com/indices/global/ticker/short?crypto=BTC"); private static final String BITCOINAVERAGE_SOURCE = "BitcoinAverage.com"; 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(); 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 Map<String, ExchangeRate> requestExchangeRates() { final Stopwatch watch = Stopwatch.createStarted(); final Request.Builder request = new Request.Builder(); request.url(BITCOINAVERAGE_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 JSONObject head = new JSONObject(content); final Map<String, ExchangeRate> rates = new TreeMap<String, ExchangeRate>(); for (final Iterator<String> i = head.keys(); i.hasNext();) { final String currencyCode = i.next(); if (currencyCode.startsWith("BTC")) { final String fiatCurrencyCode = currencyCode.substring(3); if (!fiatCurrencyCode.equals(MonetaryFormat.CODE_BTC) && !fiatCurrencyCode.equals(MonetaryFormat.CODE_MBTC) && !fiatCurrencyCode.equals(MonetaryFormat.CODE_UBTC)) { final JSONObject exchangeRate = head.getJSONObject(currencyCode); final JSONObject averages = exchangeRate.getJSONObject("averages"); try { final Fiat rate = parseFiatInexact(fiatCurrencyCode, averages.getString("day")); if (rate.signum() > 0) rates.put(fiatCurrencyCode, new ExchangeRate( new org.bitcoinj.utils.ExchangeRate(rate), BITCOINAVERAGE_SOURCE)); } catch (final IllegalArgumentException x) { log.warn("problem fetching {} exchange rate from {}: {}", currencyCode, BITCOINAVERAGE_URL, x.getMessage()); } } } } watch.stop(); log.info("fetched exchange rates from {}, {} chars, took {}", BITCOINAVERAGE_URL, content.length(), watch); return rates; } else { log.warn("http status {} when fetching exchange rates from {}", response.code(), BITCOINAVERAGE_URL); } } catch (final Exception x) { log.warn("problem fetching exchange rates from " + BITCOINAVERAGE_URL, x); } return null; } // backport from bitcoinj 0.15 private static Fiat parseFiatInexact(final String currencyCode, final String str) { final long val = new BigDecimal(str).movePointRight(Fiat.SMALLEST_UNIT_EXPONENT).longValue(); return Fiat.valueOf(currencyCode, val); } }