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How to use preloaded database in Android correctly

I want to use a preloaded database. The database must be attached to the application, and then be able to update. I have a number of doubts about how to connect it to avoid problems. I ask professionals who deal with this problem to answer. Thanks.

  • If my database is larger than 1 MB, it throws a D / asset error (909): data exceeds UNCOMPRESS_DATA_MAX. They can be broken into chunks smaller than 1 megabyte and can be changed to enlarge (".Jpg", "Jpeg", ".Png", "Gif", ".wav", ".png", "." Mpg ", "mid", "midi", "smf", "jet", ". rtttl", ".mp3", "mpg", ". imy", "xmf", "mp4", "m4a", ". m4v "," .3 gp "," .3 gpp "," .3 g2 "," .3 gpp2 "," amr "," .bb "," wma ",". Wmv "). Which option is better (easier - change the extension).

  • Perhaps there is no "There is no such android_metadata table", but I manually added en_US to the database, but what if the application is multilingual?

  • When reading a database, I use the mDb = getReadableDatabase (); method, but I'm at the end of a private read - mDb.close (); As they say on the Internet, some mistake may not bother. Unable to open the database file. This is especially true for HTC devices.

The following quotation code

public class QuestionsDbAdapter extends SQLiteOpenHelper { private String DATABASE_PATH = "/data/data/YOUR_PACKAGE/"; public static final String DATABASE_NAME = "mantestQuestions"; public static final String TABLE_QUESTIONS = "Questions"; public static final String QUESTIONS_COLUMN_ID = "_id"; public static final String QUESTIONS_COLUMN_QUESTION ="Question"; public static final String TABLE_ANSWERS = "Answers"; public static final String ANSWERS_COLUMN_ID = "_id"; public static final String ANSWERS_COLUMN_QUESTION_ID = "QuestionId"; public static final String ANSWERS_COLUMN_ANSWER = "Answer"; public static final String ANSWERS_COLUMN_POINT = "Point"; private SQLiteDatabase mDb; private final Context mContext; private boolean mCreateDatabase = false; private boolean mUpgradeDatabase = false; /** * Constructor * Takes and keeps a reference of the passed context in order to access * the application assets and resources * @param context */ public QuestionsDbAdapter(Context context) { super(context, DATABASE_NAME, null, context.getResources().getInteger(R.integer.questionDbVersion)); mContext = context; } public void initializeDatabase(String path) { DATABASE_PATH = path; getWritableDatabase(); if(mUpgradeDatabase) { mContext.deleteDatabase(DATABASE_NAME); } if(mCreateDatabase || mUpgradeDatabase) { try { copyDatabase(); } catch (IOException e) { throw new Error("Error copying database"); } } } private void copyDatabase() throws IOException { close(); InputStream input = mContext.getAssets().open(DATABASE_NAME); String outFileName = DATABASE_PATH + DATABASE_NAME; OutputStream output = new FileOutputStream(outFileName); // Transfer bytes from the input file to the output file byte[] buffer = new byte[1024]; int length; while ((length = input.read(buffer)) > 0) { output.write(buffer, 0, length); } output.flush(); output.close(); input.close(); getWritableDatabase().close(); } public QuestionsDbAdapter open() throws SQLException { mDb = getReadableDatabase(); return this; } public void CleanUp() { mDb.close(); } @Override public void onCreate(SQLiteDatabase db) { mCreateDatabase = true; } @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { mUpgradeDatabase = true; } /** * Public helper methods */ public Cursor getQuestionById(long rowId) throws SQLException { Cursor cursor = mDb.query(true, TABLE_QUESTIONS, new String[] { QUESTIONS_COLUMN_ID, QUESTIONS_COLUMN_QUESTION }, QUESTIONS_COLUMN_ID + "=" + rowId, null, null, null, null, null); return cursor; } public Cursor getAnswerById(long rowId) throws SQLException { Cursor cursor = mDb.query(true, TABLE_ANSWERS, new String[] { ANSWERS_COLUMN_ID, ANSWERS_COLUMN_QUESTION_ID, ANSWERS_COLUMN_ANSWER, ANSWERS_COLUMN_POINT }, ANSWERS_COLUMN_ID + "=" + rowId, null, null, null, null, null); return cursor; } public Cursor getAnswersByQuestionId(long questionId) throws SQLException { Cursor cursor = mDb.query(true, TABLE_ANSWERS, new String[] {ANSWERS_COLUMN_ANSWER, ANSWERS_COLUMN_POINT}, ANSWERS_COLUMN_QUESTION_ID + "=" + questionId, null, null, null, null, null); return cursor; } public long getCount() { String sql = "SELECT COUNT(*) FROM " + TABLE_QUESTIONS; SQLiteStatement statement = mDb.compileStatement(sql); long count = statement.simpleQueryForLong(); return count; } }
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2 answers

This messy code doesn't need to be a good solution for you Android SQLiteAssetHelper

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I think the problem is that you just need to store your images in a mobile application, but if its size is very large, then extract it from the server, thanks for @confucius for this article, it really helps, but here is one more step by step tutorial that explains how to use sqlite browser to create a preloaded database in android

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