com.redhat.victims.VictimsService.java Source code

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Here is the source code for com.redhat.victims.VictimsService.java

Source

package com.redhat.victims;

/*
 * #%L
 * This file is part of victims-lib.
 * %%
 * Copyright (C) 2013 The Victims Project
 * %%
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero 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 Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 * #L%
 */

import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.MalformedURLException;
import java.net.URL;
import java.text.SimpleDateFormat;
import java.util.Date;

import org.apache.commons.io.FileUtils;
import org.apache.commons.io.FilenameUtils;
import org.apache.commons.io.IOUtils;

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.stream.JsonReader;

/**
 * 
 * This implements a basic wrapper for the victims web service. Provides basic
 * interactions with the REST interface.
 * 
 * @author gcmurphy
 * @author abn
 * 
 */
public class VictimsService {
    protected String baseURI;
    protected String serviceEntry;

    /**
     * Create a VictimsService instance with the default uri and entry point.
     * 
     * @throws MalformedURLException
     */
    public VictimsService() throws MalformedURLException {
        this.baseURI = VictimsConfig.uri();
        this.serviceEntry = VictimsConfig.entry();

    }

    /**
     * 
     * Get all new records after a given date.
     * 
     * @param since
     *            The date from when updates are required for.
     * @return
     * @throws IOException
     */
    public RecordStream updates(Date since) throws IOException {
        return fetch(since, "update");
    }

    /**
     * 
     * Get all records removed after a given date.
     * 
     * @param since
     *            The date from when removed records are required for.
     * @return
     * @throws IOException
     */
    public RecordStream removed(Date since) throws IOException {
        return fetch(since, "remove");
    }

    /**
     * 
     * Work horse method that provides a {@link RecordStream} wraped from a
     * response received from the server.
     * 
     * @param since
     *            The date from when removed records are required for.
     * @param type
     *            The service type. To be used as ${base-uri}/${service}/%{type}
     * @return
     * @throws IOException
     */
    protected RecordStream fetch(Date since, String type) throws IOException {
        SimpleDateFormat fmt = new SimpleDateFormat(VictimsRecord.DATE_FORMAT);
        String spec = FileUtils.getFile(serviceEntry, type, fmt.format(since)).toString();
        spec = FilenameUtils.normalize(spec, true);
        URL merged = new URL(new URL(baseURI), spec);
        return new RecordStream(merged.toString());
    }

    /**
     * This provides a simple ObjectStream like implementation for wrapping
     * streamed responses from the server.
     * 
     * @author abn
     * 
     */
    public static class RecordStream {
        protected JsonReader json;
        protected InputStream in;
        protected Gson gson;

        /**
         * Create a record stream from a given URI.
         * 
         * @param uri
         * @throws IOException
         */
        public RecordStream(String uri) throws IOException {
            this(new URL(uri).openStream());
        }

        /**
         * Create a record stream from a given input stream. we expect the
         * stream to contain a json response of the for [{"fields" : {
         * {@link VictimsRecord} String}}]
         * 
         * @param in
         * @throws IOException
         */
        public RecordStream(InputStream in) throws IOException {
            this.in = in;
            this.gson = new GsonBuilder().setDateFormat(VictimsRecord.DATE_FORMAT).create();
            this.json = new JsonReader(new InputStreamReader(in, "UTF-8"));
            this.json.beginArray();
        }

        /**
         * 
         * @return The next available {@link VictimsRecord}. If none available
         *         returns null.
         * @throws IOException
         */
        public VictimsRecord getNext() throws IOException {
            if (hasNext()) {
                json.beginObject();
                json.nextName(); // discard fields
                VictimsRecord v = gson.fromJson(json, VictimsRecord.class);
                json.endObject();
                return v;
            }
            return null;
        }

        /**
         * Checks if the internal {@link JsonReader} has any more json strings
         * available. If not we end the json array and close the response
         * stream.
         * 
         * @return <code>true</code> if more records can be read, else returns
         *         <code>false</code>.
         * @throws IOException
         */
        public boolean hasNext() throws IOException {
            if (!json.hasNext()) {
                json.endArray();
                IOUtils.closeQuietly(in);
                return false;
            }
            return true;
        }
    }
}