我丢了过去3小时试图做到这一点。林做一个应用程序，将随充满，不会对客户端设备改变填充表的数据库。 我设法把它的资产的文件夹并将其复制为字节流到手机上的相应数据的文件夹来做到这一点。问题是，当我想更新数据库，我不能让它的工作。我删除数据库中的数据文件夹中的手机（由code），而将新的数据库总是失败，或者拷贝数据库具有适当的大小，但它没有表。 如何做到这一点？还是有更简单的方法？我可以直接从资产打开DB（这将是，如果它可以最简单的方法，但我不能找到如何从code访问路径资产）？

I lost last 3 hours trying to do this. Im making an app that will ship with a DB filled with populated tables that would not change on clients devices. I managed to do this by putting it in the assets folder and copying it as a stream of bytes to the appropriate data folder on the phone. Problem is when I wish to update the database, I cant get it to work. I delete the DB in data folder on phone (from code), but copying the new database always fails, or the copied DB has the appropriate size but no tables in it. How to do this? Or is there a simpler way? Can I open DB directly from assets (it would be the simplest way if it can, but I cant find how to access the path to assets from code)?

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下面是我使用的code：

Here is the code I am using:

public class DataBaseHelper extends SQLiteOpenHelper {

    private static final String DB_PATH = "/data/data/com.project.mydb/databases/";
    private static final String DB_NAME = "mydb.db";
    private static final String DB_TABLE = "words";
    private static final int DB_VERSION = 6;
    private static final String TAG = "DataBaseHelper";
    int id = 0;
    Random random = new Random();
    private SQLiteDatabase myDataBase;
    private final Context myContext;

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

    @Override
    public void onCreate(SQLiteDatabase db){
        createDB();
    }

    @Override
    public void onUpgrade (SQLiteDatabase db, int oldVersion, int newVersion){
        Log.w(TAG, "Upgrading DB from version " + oldVersion + " to " +
                newVersion + ", which will destroy all old data");
        db.execSQL("DROP TABLE IF EXISTS " + DB_TABLE);
        onCreate(db);
    }

    public void createDataBase(){
        createDB();
    }

    private void createDB(){
        boolean dbExist = dbExists();
        if(!dbExist){
            copyDataBase();
        }
        else if(dbExist){
            copyDataBase();
        }
    }

    private boolean dbExists(){
        SQLiteDatabase db = null;
        try{
            String dbPath = DB_PATH + DB_NAME;
            db = SQLiteDatabase.openDatabase(dbPath, null, SQLiteDatabase.OPEN_READWRITE);
            db.setLocale(Locale.getDefault());
            db.setLockingEnabled(true);
            db.setVersion(DB_VERSION);
        }
        catch(SQLiteException e){
            Log.e("SQL Helper", "database not found");
        }
        if(db != null){
            db.close();
        }
        return db != null ? true : false;
    }

    private void copyDataBase(){
        InputStream iStream = null;
        OutputStream oStream = null;
        String outFilePath = DB_PATH + DB_NAME;
        try{
            iStream = myContext.getAssets().open(DB_NAME);
            oStream = new FileOutputStream(outFilePath);
            byte[] buffer = new byte[1024];
            int length;
            while((length = iStream.read(buffer))>0){
                oStream.write(buffer,0,length);
            }
            oStream.flush();
            oStream.close();
            iStream.close();
        }
        catch(IOException ioe){
            throw new Error("Problem copying database from resource file.");
        }
    }

    public void openDataBase() throws SQLException {
        String myPath = DB_PATH + DB_NAME;
        myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READWRITE);
    }

    @Override
    public synchronized void close(){
        if (myDataBase != null)
            myDataBase.close();
        super.close();
    }
}