Android: How to create an external Sqlite database dynamically?

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Android: How to create an external Sqlite database dynamically?

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I have been thoroughly researching on this and all the examples I found and tested did not work. To leave the code more organized I would like to do this using the OpenHelper class but I have already tested the openOrCreate () method on both OpenHelper and Activity itself. Here is my code:

public class CriaBancoApp extends SQLiteOpenHelper {

    private static final String NOME_BANCO = "BD_AppNome.db";
    private static final String CAMINHO_BANCO = Environment.getExternalStorageDirectory() + "/AppNome/Databases/";
    private static final int VERSAO = 1;


    public CriaBancoApp(Context contexto) {
        super(contexto, CAMINHO_BANCO, null, VERSAO); 
       //SQLiteDatabase.openOrCreateDatabase(CAMINHO_BANCO, null); 
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        String sql = "CREATE TABLE NomeTabela (" 
                + "Id INTEGER PRIMARY KEY AUTOINCREMENT,"
                + "AutorTraducao TEXT)";
                db.execSQL(sql);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        db.execSQL("DROP TABLE IF EXISTS NomeTabela");
        onCreate(db);
    }

}

Then I create the instance in MainActivity:

CriaBancoApp banco = new CriaBancoApp(this);

And when starting the app date. Regarding the path the app folders are created before creating the database I even commented this line to check if the folders are created and are. The xml Manifest already has write permission that automatically includes the read permission.

android sqlite portabilidade

asked by anonymous 18.06.2018 / 20:18

1 answer

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score 0 · Accepted Answer

Well, after a lot of research I decided to study the parent class SQLiteOpenHelper and found that it uses the context to define the path where the database will be created. Based on this I have changed the focus of the search to how to customize a context with the path I want. In this search I came up with this answer: link that solved the problem. As it was all in English, I made my adaptation of this answer to Portuguese it looked like this:

In the CreateBancoApp class I modified the constructor:

    public CriaBancoApp(Context contexto) {
        super(new ContextoBanco(contexto, CAMINHO_BANCO), NOME_BANCO, null, VERSAO);
    }

Then I created a class responsible for customizing the context:

public class ContextoBanco extends ContextWrapper {
    private static final String DEPURAR_CONTEXTO = "ContextoBanco";
    private String caminho;

    public ContextoBanco(Context base, String caminho) {
        super(base);
        this.caminho = caminho;
    }

    @Override
    public File getDatabasePath(String name)  {
        String caminho_banco = caminho + name;
        if (!caminho_banco.endsWith(".db")) {
            caminho_banco += ".db" ;
        }

        File result = new File(caminho_banco);

        if (!result.getParentFile().exists()) {

            result.getParentFile().mkdirs();
        }

        if (Log.isLoggable(DEPURAR_CONTEXTO, Log.WARN)) {
         Log.w(DEPURAR_CONTEXTO, "getDatabasePath(" + name + ") = " + result.getAbsolutePath());
        }

        return result;
    }

    /* Esta versão é chamada para dispositivos Android >= api-11. */
    @Override
    public SQLiteDatabase openOrCreateDatabase(String name, int mode, SQLiteDatabase.CursorFactory factory, DatabaseErrorHandler errorHandler) {
        return openOrCreateDatabase(name,mode, factory);
    }

    /* Esta versão é chamada para dispositivos Android < api-11 */
    @Override
    public SQLiteDatabase openOrCreateDatabase(String name, int mode, SQLiteDatabase.CursorFactory factory) {
        SQLiteDatabase result = SQLiteDatabase.openOrCreateDatabase(getDatabasePath(name), null);
        if (Log.isLoggable(DEPURAR_CONTEXTO, Log.WARN)) {
         Log.w(DEPURAR_CONTEXTO, "openOrCreateDatabase(" + name + ",,) = " + result.getPath());
        }
        return result;
    }

}

And in MainActivity besides creating an instance of the class BankApp, it is necessary to make a query for the database to be created:

        SQLiteDatabase db;
        CriaBancoApp banco = new CriaBancoApp(this);
        String[] campos = {"Id","Nome","Idade","Etc"};
        String condicao = " Id > 0 ";
        Cursor dados = null;

        db = banco.getReadableDatabase();

        dados = db.query("Nome_da_Tabela", campos, condicao, null, null, null, null);

        if(dados != null) {

            if(dados.moveToNext()) {
                // Registro encontrado
            } else {
                // Não há registros na tabela
            }
        }

Even though I had found my answer, I felt it was my duty to publish to help others who might need it, after all it was very time consuming for me to find.