Get the SQLite path within the Assets Folder

I'm developing an application and I've run into two problems here:

1. How can I open an SQLite database which is stored in the assets folde开发者_运维知识库r? What path do I use to access the assets folder in my application? Here's what I have so far:

   path = "file:///asset_folder/database.dat";
   SQLiteDatabase db = null;
   db = SQLiteDatabase.openDatabase(path, null, SQLiteDatabase.OPEN_READONLY);
   

2. How can I copy a file to the internal memory (/data/data/...) during the installation of my application or during the first run? I want to copy a folder inside the assets folder into the internal memory during the first run.

Any suggestions would be greatly appreciated.

I was having the same problem, so I moved the db file to the res/raw folder, and accessed it like so:

InputStream inputStream = getBaseContext().getResources().openRawResource(R.raw.mySQLiteFile);

Then I tried to move the file into the /data/data/com.mydomain.www/databases/ folder, but I would get an exception because the destination path didn't exist, so I did File(destPath).getParentFile().mkdir();

From there, I called a copy db method to transfer the db to the destination.

public void CopyDB(InputStream inputStream, OutputStream outputStream) throws IOException {
        byte[] buffer = new byte[1024];
        int length;
        while ((length = inputStream.read(buffer)) > 0) {
            outputStream.write(buffer, 0, length);
        }
        inputStream.close();
        outputStream.close();
    }

InputStream is the db file, OutputStream is the FileOutputStream(destPath).

From this post i found this tutorial. It tells you how to deal with databases in your assets folder. That at least answers your first question. I'm not too sure about your second.

Copy database from assets folder to data/data/database folder of your application. Use Below code.

import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.database.sqlite.SQLiteOpenHelper;

public class DataBaseHelper1 extends SQLiteOpenHelper{

//The Android's default system path of your application database.
public static String DB_PATH = "/data/data/com.XXX.XXX/databases/";
private static String DB_NAME = "india.sqlite";
private static String DB_NAME_MY = "india.sqlite";
private SQLiteDatabase myDataBase; 
private final Context myContext;

/**
 * Constructor
 * Takes and keeps a reference of the passed context in order to access to the  application assets and resources.
 * @param context
 */

public DataBaseHelper1(Context context){
    super(context, DB_NAME, null, 1);
    this.myContext = context;
 }  

/**
 * Creates a empty database on the system and rewrites it with your own database.
 * */
public void createDataBase() throws IOException{
    // for first database;
    boolean dbExist = checkDataBase(DB_NAME);
    if(!dbExist){
        try {
            copyDataBase(DB_NAME_MY,DB_NAME);
        } catch (Exception e) {
            throw new Error("Error copying database");
        }
    }
}

/**
 * Check if the database already exist to avoid re-copying the file each time you open the application.
 * @return true if it exists, false if it doesn't
 */
private boolean checkDataBase(String DB){
    SQLiteDatabase checkDB = null;
    try{
        String myPath = DB_PATH + DB;
        checkDB = SQLiteDatabase.openDatabase(myPath, null,  SQLiteDatabase.OPEN_READONLY);

    }catch(SQLiteException e){}

    if(checkDB != null){

        checkDB.close();

    }

    return checkDB != null ? true : false;
}

/**
 * Copies your database from your local assets-folder to the just created empty database in the
 * system folder, from where it can be accessed and handled.
 * This is done by transfering bytestream.
 * */
private void copyDataBase(String assetfile,String DB) {

    //Open your local db as the input stream
    InputStream myInput = null;
    //Open the empty db as the output stream
    OutputStream myOutput = null;
    try {
        myInput = myContext.getAssets().open(assetfile);

        // Path to the just created empty db
        String outFileName = DB_PATH + DB;

        myOutput = new FileOutputStream(outFileName);

        //transfer bytes from the inputfile to the outputfile
        byte[] buffer = new byte[1024];
        int length;
        while ((length = myInput.read(buffer))>0){
            myOutput.write(buffer, 0, length);
        }


        System.out.println("***************************************");
        System.out.println("####### Data base copied ##############");
        System.out.println("***************************************");


    } catch (FileNotFoundException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
     }
          finally{
          //Close the streams
          try {
        myOutput.flush();
        myOutput.close();
        myInput.close();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
 }

}

public void openDataBase() {

    try {
        //Open the database
        String myPath = DB_PATH + DB_NAME;
        myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);
    } catch (Exception e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

}

@Override
public synchronized void close() {

        if(myDataBase != null)
            myDataBase.close();

        super.close();

}

@Override
public void onCreate(SQLiteDatabase db) {

}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

}

    // Add your public helper methods to access and get content from the database.
   // You could return cursors by doing "return myDataBase.query(....)" so it'd be easy
   // to you to create adapters for your views.

 }