BackupAgent for Android Backup Service

BackupAgent

package com.dvlab.birthdaynotes.services;

import android.app.backup.BackupDataInput;
import android.app.backup.BackupDataOutput;
import android.os.ParcelFileDescriptor;
import android.util.Log;

import com.dvlab.birthdaynotes.entities.Person;
import com.dvlab.birthdaynotes.repositories.PeopleRepo;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

/**
 * cd ~/Android/Sdk/platform-tools
 * ./adb shell bmgr backup com.dvlab.birthdaynotes
 * ./adb shell bmgr run
 * ./adb shell bmgr restore com.dvlab.birthdaynotes
 * <p>
 * ./adb shell bmgr list transports
 * ./adb shell bmgr transport android/com.android.internal.backup.LocalTransport
 * ./adb shell bmgr transport com.google.android.gms/.backup.BackupTransportService
 */
public class BackupAgent extends android.app.backup.BackupAgent {

    final public static String TAG = BackupAgent.class.getSimpleName();
    final private static String BACKUP_KEY = "people";

    @Override
    public void onBackup(ParcelFileDescriptor oldState, BackupDataOutput data, ParcelFileDescriptor newState) throws IOException {
        Log.d(TAG, "onBackup");

        List<Person> people = PeopleRepo.findAll();
        JSONArray json = new JSONArray();
        for (Person person : people) {
            JSONObject personJSON = person.toJSON(getFilesDir());
            json.put(personJSON);
        }
        Log.d(TAG, json.toString());

        byte[] buffer = json.toString().getBytes();
        int len = buffer.length;
        data.writeEntityHeader(BACKUP_KEY, len);
        data.writeEntityData(buffer, len);
    }

    @Override
    public void onRestore(BackupDataInput data, int appVersionCode, ParcelFileDescriptor newState) throws IOException {
        Log.d(TAG, "onRestore");

        // There should be only one entity, but the safest
        // way to consume it is using a while loop
        while (data.readNextHeader()) {
            String key = data.getKey();
            int dataSize = data.getDataSize();

            if (BACKUP_KEY.equals(key)) {
                byte[] buffer = new byte[dataSize];
                data.readEntityData(buffer, 0, dataSize);

                try {
                    JSONArray json = new JSONArray(new String(buffer));
                    List<Person> people = new ArrayList<>(json.length());
                    for (int i = 0; i < json.length(); i++) {
                        Person person = new Person(json.getJSONObject(i), getFilesDir());
                        people.add(person);
                    }
                    PeopleRepo.restoreBackup(people);
                } catch (JSONException e) {
                    Log.e(TAG, e.getMessage(), e);
                }
            }
        }
    }
}