FileHandler.java

package se.dat255.grupp12;

import android.app.Activity;
import android.content.Context;
import android.util.JsonReader;

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.reflect.TypeToken;

import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.Reader;
import java.io.StringReader;
import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;
import java.util.Scanner;

/**
 * Responsible class for saving lists locally when the application is being shut down and
 * opening them when the it's reopened
 * Created by David on 10/7/13.
 */
public class FileHandler {

    private final GsonBuilder gsonBuilder = new GsonBuilder();
    private final Gson gson = gsonBuilder.create();

    private final String LISTFILE = "list_file";
    private final String LOGFILE = "log_file";
    private final String IPFILE = "ip_file";


    public FileHandler(){}


    /**
     * Converts a list into a json formatted string ie. writes to the file
     * @param list  the list that is to be converted
     * @param context   the context from where the file should be written
     * @throws IOException
     */
    public void writeListToJson(List list, Context context, String fileName) throws IOException{
        FileOutputStream fos;
        String json = "";

        if(fileName.equals(LISTFILE)){
            fos = context.openFileOutput(LISTFILE, Context.MODE_PRIVATE);
            json = gson.toJson(list, new TypeToken<ArrayList<TodoList>>(){}.getType());

        }else{
            fos = context.openFileOutput(LOGFILE, Context.MODE_PRIVATE);
            json = gson.toJson(list, new TypeToken<LinkedList<Modification>>(){}.getType());
        }

        System.out.println(json+ "json");

        fos.write(json.getBytes());
        fos.close();


    }

    /**
     * Saves the currently used IP address.
     * @param context
     * @throws IOException
     */
    public void writeAddress(Context context) throws IOException {
        FileOutputStream fos;
        String json = "";

        fos = context.openFileOutput(IPFILE, Context.MODE_PRIVATE);
        json = gson.toJson(ServerConnection.getAddress());

        fos.write(json.getBytes());
        fos.close();
    }

    /**
     * Creates a list of todolists or log from a json object/string ie. reads the file
     * @param activity the activity in which the filewriting takes place
     * @return  the list of todolists extracted from the file
     * @throws IOException if reading somehow fails
     */
    public List readListFromJson(Activity activity, String fileName) throws IOException{
        ArrayList<TodoList> list = new ArrayList<TodoList>();
        FileInputStream fis;
        try{
            if(fileName.equals(LISTFILE)){
                fis = activity.openFileInput(LISTFILE);
            }else{
                fis = activity.openFileInput(LOGFILE);
            }
        }catch(FileNotFoundException e){
            return list;
        }

        byte content[] = new byte[fis.available()];

        fis.read(content);

        String json = new String(content);

        com.google.gson.stream.JsonReader reader = new com.google.gson.stream.JsonReader(
                new StringReader(json)
        );
        reader.setLenient(true);
        if(fileName.equals(LISTFILE)){
            list = gson.fromJson(reader, new TypeToken<ArrayList<TodoList>>(){}.getType());
            return list;
        }else{
            LinkedList log = gson.fromJson(reader,
                                            new TypeToken<LinkedList<Modification>>(){}.getType());
            return log;
        }
    }

    public void readAddressFromFile(Context activity) throws IOException {
        String address = "";
        FileInputStream fis = null;
        try{
            fis = activity.openFileInput(IPFILE);


            byte content[] = new byte[fis.available()];

            fis.read(content);

            String json = new String(content);

            com.google.gson.stream.JsonReader reader = new com.google.gson.stream.JsonReader(
                    new StringReader(json)
            );
            reader.setLenient(true);

            address = gson.fromJson(reader,String.class);

            ServerConnection.setAddress(address);

        }catch(FileNotFoundException e){
            ServerConnection.setAddress(address);
        }catch(NullPointerException e){
            ServerConnection.setAddress(address);
        }
    }

}