com.google.iosched.input.fetcher.RemoteJsonHelper.java Source code

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Here is the source code for com.google.iosched.input.fetcher.RemoteJsonHelper.java

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/*
 * Copyright 2014 Google Inc. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.google.iosched.input.fetcher;

import com.google.gson.JsonArray;
import com.google.gson.JsonElement;
import com.google.gson.JsonObject;
import com.google.gson.JsonParser;
import com.google.gson.stream.JsonReader;
import com.google.iosched.Config;

import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.nio.charset.Charset;
import java.util.Map.Entry;

/**
 */
public class RemoteJsonHelper {

    public static JsonObject mergeJsonFiles(JsonObject target, String... filenames) throws IOException {
        if (target == null) {
            target = new JsonObject();
        }
        for (String filename : filenames) {
            String url = Config.CLOUD_STORAGE_BASE_URL + filename;
            JsonObject obj = fetchJsonFromPublicURL(url);
            if (obj == null) {
                throw new FileNotFoundException(url);
            } else {
                for (Entry<String, JsonElement> entry : obj.entrySet()) {
                    if (entry.getValue().isJsonArray()) {
                        // tries to merge an array with the existing one, if it's the case:
                        JsonArray existing = target.getAsJsonArray(entry.getKey());
                        if (existing == null) {
                            existing = new JsonArray();
                            target.add(entry.getKey(), existing);
                        }
                        existing.addAll(entry.getValue().getAsJsonArray());
                    } else {
                        target.add(entry.getKey(), entry.getValue());
                    }
                }
            }
        }
        return target;
    }

    public static JsonObject fetchJsonFromPublicURL(String urlStr) throws IOException {
        URL url = new URL(urlStr);

        HttpURLConnection connection = (HttpURLConnection) url.openConnection();
        connection.setReadTimeout(1000 * 30); // 30 seconds
        int response = connection.getResponseCode();
        if (response < 200 || response >= 300) {
            throw new IllegalArgumentException("Unexpected HTTP response [" + response + "] at URL: " + urlStr);
        }

        InputStream stream = connection.getInputStream();
        JsonReader reader = new JsonReader(new InputStreamReader(stream, Charset.forName("UTF-8")));
        return (JsonObject) new JsonParser().parse(reader);
    }

}