org.quickgeo.PostalDbFactory.java Source code

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Here is the source code for org.quickgeo.PostalDbFactory.java

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/*
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. 
 */

package org.quickgeo;

import com.google.common.collect.Sets;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.LinkedHashSet;
import java.util.ServiceLoader;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 * Factory class for creating PostalDb instances.  It really is as simple as it
 * looks, just use the {@link #build() build} method and use the returned
 * PostalDb instance.
 * 
 * @author Jason Nichols (jason@kickroot.com)
 * @since 0.1.0
 */
public class PostalDbFactory {

    ///////////////////////////// Class Attributes \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\

    private static ServiceLoader<PostalSource> SERVICE_LOADER = ServiceLoader.load(PostalSource.class);

    private static final PostalDb db = build();

    ////////////////////////////// Class Methods \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\

    /**
     * Returns a VM wide {@link PostalDb} instance.  Given that instantiating a PostalDb
     * instance is resource intensive, a single instance is generated at class
     * loading time with a static initializer and used throughout the VM.
     * 
     * Since PostalDb instances are immutable, sharing a single instance amongst
     * threads is perfectly safe, and in this case preferable.
     * 
     * @return The previously generated PostalDb instance.
     * @since 0.1.0
     */
    public static PostalDb getPostalDb() {
        return db;
    }

    /**
     * Builds a new PostalDb instance, with all postal data stored in memory.  This process
     * is somewhat resource intensive and should only be done once per application
     * instance. Given that {@link PostalDb} instances are immutable, the instance should 
     * be freely shared among threads.
     * 
     * @return A new PostalDb instance.
     * @since 0.1.0
     */
    private static PostalDb build() {

        LinkedHashSet<Place> set = Sets.newLinkedHashSet();

        for (PostalSource source : SERVICE_LOADER) {
            try {
                BufferedReader in = new BufferedReader(new InputStreamReader(source.getStream()));
                String line = null;

                while ((line = in.readLine()) != null) {
                    try {
                        Place p = PlaceFactory.fromLine(line);
                        set.add(p);
                    } catch (Exception ex) {
                        Logger.getLogger(PostalDbFactory.class.getName()).log(Level.INFO,
                                "Couldn''t read line : {0}", ex.getMessage());
                    }
                }
                in.close();
            } catch (Exception ex) {
                Logger.getLogger(PostalDbFactory.class.getName()).log(Level.INFO, "Couldn''t read source : {0}",
                        ex.getMessage());
            }
        }

        return new PostalDb(set);
    }

    //////////////////////////////// Attributes \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\

    /////////////////////////////// Constructors \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\  

    ////////////////////////////////// Methods \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\

    //------------------------ Implements:

    //------------------------ Overrides:

    //---------------------------- Abstract Methods -----------------------------

    //---------------------------- Utility Methods ------------------------------

    //---------------------------- Property Methods -----------------------------     
}