com.mecatran.otp.gwt.client.utils.HttpUtils.java Source code

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Here is the source code for com.mecatran.otp.gwt.client.utils.HttpUtils.java

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/* -------------------------------------------------------------------------
OpenTripPlanner GWT Client
Copyright (C) 2015 Mecatran - info@mecatran.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 2 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, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
   ------------------------------------------------------------------------- */
package com.mecatran.otp.gwt.client.utils;

import com.google.gwt.core.client.JavaScriptObject;
import com.google.gwt.core.client.JsonUtils;
import com.google.gwt.http.client.Request;
import com.google.gwt.http.client.RequestBuilder;
import com.google.gwt.http.client.RequestCallback;
import com.google.gwt.http.client.RequestException;
import com.google.gwt.http.client.Response;

public class HttpUtils {

    public static final int DEFAULT_TIMEOUT_MS = 10000;

    public interface DownloadListener<T> {

        public void onSuccess(T t);

        public void onFailure(String msg);
    };

    private interface DataConverter<T> {
        public T convert(String data) throws Exception;
    }

    public static <T extends JavaScriptObject> void downloadJson(String url, final DownloadListener<T> listener) {
        downloadJson(url, listener, DEFAULT_TIMEOUT_MS);
    }

    public static <T extends JavaScriptObject> void downloadJson(String url, final DownloadListener<T> listener,
            int timeoutMs) {
        downloadData(url, "application/json", listener, new DataConverter<T>() {
            @Override
            public T convert(String data) {
                return JsonUtils.<T>safeEval(data);
            }
        }, timeoutMs);
    }

    public static <T> void downloadData(String url, String contentType, final DownloadListener<T> listener,
            final DataConverter<T> converter, int timeoutMs) {
        try {
            RequestBuilder builder = new RequestBuilder(RequestBuilder.GET, url);
            builder.setTimeoutMillis(timeoutMs);
            builder.setHeader("Accept", contentType);
            builder.sendRequest(null, new RequestCallback() {

                public void onError(Request request, Throwable exception) {
                    listener.onFailure(exception.getLocalizedMessage());
                }

                public void onResponseReceived(Request request, Response response) {
                    if (200 == response.getStatusCode()) {
                        try {
                            T t = converter.convert(response.getText());
                            listener.onSuccess(t);
                        } catch (Exception e) {
                            listener.onFailure(e.getLocalizedMessage());
                        }
                    } else {
                        listener.onFailure(response.getStatusText());
                    }
                }
            });
        } catch (RequestException e1) {
            listener.onFailure(e1.getLocalizedMessage());
        }
    }
}