Android Open Source - Race2GED2 Class Data Reader

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Apache License Version 2.0, January 2004 http://www.apache.org/licenses/ TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 1. Def...

Java Source Code

/*
 * Copyright 2014 Regional Adult Education Program of Lee, Scott, Wise, and Norton Public Schools
 *//from   www .  j  a v a2  s. c  o m
 *    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 edu.mecc.race2ged.helpers;

import android.app.Activity;
import android.content.Context;
import android.os.AsyncTask;
import android.util.Log;
import android.view.View;
import android.widget.TextView;
import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import edu.mecc.race2ged.JSON.*;
import edu.mecc.race2ged.R;

/**
 * ClassDataReader loads JSON Class data and parses it to the associated objects to be easily used.
 *
 * @author Bryan Smith
 */
public class ClassDataReader extends AsyncTask<Integer, Void, Region> {

    public static String dataRead = "Class Data Loaded.";
    public static String dataError = "Error Loading Class Data";
    public static String dataParse = "Loading Class Data.";

    private Activity activity = null;
    private Integer progressViewID = null;
    private View progressView = null;
    private Context context = null;

    /**
     * Creates a new asynchronous task. This constructor must be invoked on the UI thread.
     */
    public ClassDataReader(Activity activity,Integer progressViewId) {
        super();
        if (activity != null) {
            this.activity = activity;
            this.progressViewID = progressViewId;
            if (activity.findViewById(progressViewID) != null)
                progressView = activity.findViewById(progressViewID);
            this.context = activity.getApplicationContext();
        }
    }

    /**
     * Runs on the UI thread before {@link #doInBackground}.
     *
     * @see #onPostExecute
     * @see #doInBackground
     */
    @Override
    protected void onPreExecute() {
        Log.d(this.getClass().getSimpleName(),"Begin Parsing Class Data.");
        if (progressView != null && progressView instanceof TextView){
            ((TextView)progressView).setText(dataParse);
        }
    }

    /**
     * Determines which data file to read, and then parses the JSON class data. The
     * specified parameters are the parameters passed to {@link #execute}
     * by the caller of this task.
     * <p/>
     * This method can call {@link #publishProgress} to publish updates
     * on the UI thread.
     *
     * @param params The region number to retrieve.
     * @return Region object for the specified region.
     * @see #onPreExecute()
     * @see #onPostExecute
     * @see #publishProgress
     */
    @Override
    protected Region doInBackground(Integer... params) {
        String filePath = context.getFilesDir().getAbsolutePath()+
                "/"+context.getString(R.string.class_data_file_name);
        File file = new File(filePath);
        if(file.exists()) {
            Log.d(this.getClass().getSimpleName(),filePath+" => Exists. Parsing it.");
            try {
                return loadJson(params[0],context.openFileInput(context.getString(R.string.class_data_file_name)));
            } catch (IOException e) {
                Log.e(this.getClass().getSimpleName(),"Error loading JSON from internal storage.\n"+e.toString());
            }
        } else {
            Log.d(this.getClass().getSimpleName(),filePath+" => Does not exist. Parsing built in data.");
            try {
                return loadJson(params[0],context.getResources().openRawResource(R.raw.classschedule));
            } catch (IOException e) {
                Log.e(this.getClass().getSimpleName(),"Error loading JSON from pre-packaged file.\n"+e.toString());
            }
        }
        return null;
    }

    /**
     * <p>Displays if the data was read successfully. </p>
     * <p>This method won't be invoked if the task was cancelled.</p>
     *
     * @param region The result of the operation computed by {@link #doInBackground}.
     * @see #onPreExecute
     * @see #doInBackground
     * @see #onCancelled(Object)
     */
    @Override
    protected void onPostExecute(Region region) {
        Log.d(this.getClass().getSimpleName(),region.toString());
        if (progressView != null && progressView instanceof TextView){
            if (region != null) ((TextView)progressView).setText(dataRead);
            else ((TextView)progressView).setText(dataError);
        }
    }

    /**
     * Creates objects from a JSON file.
     * @param regionNumb The region number to retrieve.
     * @param iS InputStream to read JSON data from.
     * @return Region object for the specified region.
     * @throws IOException
     */
    protected Region loadJson(int regionNumb, InputStream iS) throws IOException{
        Reader reader = null;
        Region region =  null;
        try{
            reader = new InputStreamReader(iS, "UTF-8");
            Gson gson = new GsonBuilder().create();
            State state = gson.fromJson(reader, State.class);
            if (state != null) region = state.getRegion().get(regionNumb);
            else throw new NullPointerException();
        } catch (Exception e) {
            Log.e(this.getClass().getSimpleName(),"GSON Error constructing objects from JSON.\n"+e.toString());
        } finally {
            if (iS != null)
                iS.close();
            if (reader != null)
                reader.close();
        }
        Log.d(this.getClass().getSimpleName(),"Done Parsing");
        return region;
    }
}

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