com.google.gwt.sample.stockwatcher.server.CurrencyServiceImpl.java Source code

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Here is the source code for com.google.gwt.sample.stockwatcher.server.CurrencyServiceImpl.java

Source

package com.google.gwt.sample.stockwatcher.server;

import java.io.IOException;
import java.util.Date;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.HttpClientBuilder;
import org.apache.http.util.EntityUtils;

import com.google.gwt.core.client.GWT;
import com.google.gwt.i18n.shared.DateTimeFormat;
import com.google.gwt.i18n.shared.DefaultDateTimeFormatInfo;
import com.google.gwt.sample.stockwatcher.client.CurrencyService;
import com.google.gwt.user.datepicker.client.CalendarUtil;
import com.google.gwt.user.server.rpc.RemoteServiceServlet;

public class CurrencyServiceImpl extends RemoteServiceServlet implements CurrencyService {

    private static final long serialVersionUID = 1L;
    private static final String JSON_BASE_URL = "http://api.fixer.io/latest?base=HKD";
    // using String as ENUM seems flawed in GWT
    // test

    private static final String PRESENT_CURRENCY = "PRESENT_CURRENCY";
    private static final String HISTORICAL_CURRENCY = "HISTORICAL_CURRENCY";

    @Override
    public String getData(String input) {
        switch (input) {
        case PRESENT_CURRENCY:
            return getJSONDataAsString(JSON_BASE_URL);
        case HISTORICAL_CURRENCY:
            String url = calculateRatesUrl();
            return getJSONDataAsString(url);
        }
        return "";
    }

    private String getJSONDataAsString(String url) {
        HttpClient client = HttpClientBuilder.create().build();
        HttpGet request = new HttpGet(url);
        request.addHeader("accept", "application/json");
        try {
            HttpResponse response = client.execute(request);
            HttpEntity entity = response.getEntity();
            return EntityUtils.toString(entity, "UTF-8");
        } catch (ClientProtocolException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return "";
    }

    private String calculateRatesUrl() {
        String pattern = "yyyy-MM-dd";
        DefaultDateTimeFormatInfo info = new DefaultDateTimeFormatInfo();
        DateTimeFormat dtf = new DateTimeFormat(pattern, info) {
        };
        Date d = new Date();
        CalendarUtil.addMonthsToDate(d, -1);
        return "http://api.fixer.io/" + dtf.format(d) + "?base=HKD";
    }
}