piuk.blockchain.android.ExchangeRatesProvider.java Source code

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Here is the source code for piuk.blockchain.android.ExchangeRatesProvider.java

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/*
 * Copyright 2011-2012 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 piuk.blockchain.android;

import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.Reader;
import java.net.URL;
import java.net.URLConnection;
import java.util.Iterator;
import java.util.Map;
import java.util.TreeMap;

import org.json.JSONException;
import org.json.JSONObject;

import piuk.blockchain.android.util.IOUtils;

import android.content.ContentProvider;
import android.content.ContentValues;
import android.database.Cursor;
import android.database.MatrixCursor;
import android.net.Uri;
import android.provider.BaseColumns;

/**
 * @author Andreas Schildbach
 */
public class ExchangeRatesProvider extends ContentProvider {
    public static final Uri CONTENT_URI = Uri.parse("content://" + Constants.PACKAGE_NAME + '.' + "exchange_rates");

    public static final String KEY_CURRENCY_CODE = "currency_code";
    public static final String KEY_EXCHANGE_RATE = "exchange_rate";

    private Map<String, Double> exchangeRates = null;

    @Override
    public boolean onCreate() {
        return true;
    }

    @Override
    public Cursor query(final Uri uri, final String[] projection, final String selection,
            final String[] selectionArgs, final String sortOrder) {
        if (exchangeRates == null) {
            exchangeRates = getExchangeRates();

            if (exchangeRates == null)
                return null;
        }

        final MatrixCursor cursor = new MatrixCursor(
                new String[] { BaseColumns._ID, KEY_CURRENCY_CODE, KEY_EXCHANGE_RATE });

        if (selection == null) {
            for (final Map.Entry<String, Double> entry : exchangeRates.entrySet())
                cursor.newRow().add(entry.getKey().hashCode()).add(entry.getKey()).add(entry.getValue());
        } else if (selection.equals(KEY_CURRENCY_CODE)) {

            if (selectionArgs == null)
                return null;

            final String code = selectionArgs[0];
            final Double rate = exchangeRates.get(code);
            cursor.newRow().add(code.hashCode()).add(code).add(rate);
        }

        return cursor;
    }

    @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, Double> getExchangeRates() {
        try {
            final URLConnection connection = new URL("http://bitcoincharts.com/t/weighted_prices.json")
                    .openConnection();
            // https://mtgox.com/code/data/ticker.php
            // https://bitmarket.eu/api/ticker
            // http://bitcoincharts.com/t/weighted_prices.json

            connection.connect();
            final Reader is = new InputStreamReader(new BufferedInputStream(connection.getInputStream()));
            final StringBuilder content = new StringBuilder();
            IOUtils.copy(is, content);
            is.close();

            final Map<String, Double> rates = new TreeMap<String, Double>();

            final JSONObject head = new JSONObject(content.toString());
            for (@SuppressWarnings("unchecked")
            final Iterator<String> i = head.keys(); i.hasNext();) {
                final String currencyCode = i.next();
                if (!"timestamp".equals(currencyCode)) {
                    final JSONObject o = head.getJSONObject(currencyCode);
                    double rate = o.optDouble("24h", 0);
                    if (rate == 0)
                        rate = o.optDouble("7d", 0);
                    if (rate == 0)
                        rate = o.optDouble("30d", 0);

                    if (rate != 0)
                        rates.put(currencyCode, rate);
                }
            }

            return rates;
        } catch (final IOException x) {
            x.printStackTrace();
        } catch (final JSONException x) {
            x.printStackTrace();
        }

        return null;
    }
}