SQLite数据库从来没有接近我的Andr​​oid应用 [英] SQLite database never close in my Android app

问题描述

我有我的Andr​​oid应用程序的问题。我使用code波纹管在AsyncTask的打开SQLite数据库。一切工作正常，但是当我尝试在的onStop（）关闭数据库或的onDestroy 方法，它永远不会关闭。

I have a problem with my Android application. I'm using code bellow to opening SQLite database in AsyncTask. Everything works fine but when I try to close database in onStop() or onDestroy method, it's never closed.

code，用于创建和打开数据库：

公共类SQLiteDB扩展SQLiteOpenHelper {

public class SQLiteDB extends SQLiteOpenHelper{

private final Context context;  
private SQLiteDatabase sqliteDatabase = null;

public SQLiteDB(Context context, String DBName) {
    super(context, DBConstant.DB_NAME, null, context.getResources().getInteger(ppredota.android.navigation.view.activities.R.string.database_version));
    this.context = context;
}

public void createDB() throws IOException{


    if(existDB()){
        this.getReadableDatabase();
        this.close();
    }
    else {
        this.getWritableDatabase();
        try {
            copyDB();
            this.close();   
        }
        catch (Exception e) {
            throw new Error("Chyba pri kopirovani databaze");
        }
    }
}
private boolean existDB() {

    SQLiteDatabase checkDatabase = null;

    try{
        String fullPath = DBConstant.DB_PATH + DBConstant.DB_NAME;
        checkDatabase = SQLiteDatabase.openDatabase(fullPath, null, SQLiteDatabase.OPEN_READWRITE);
    }
    catch (SQLiteException sqle) {
        Log.i("existDB()", "Databaze nelze otevrit, neexistuje");
    }
    if(checkDatabase == null){
        Log.i("existDB", "Databaze jeste neexistuje...");
        return false;
    }
    else{
        Log.i("existDB", "Databaze uz existuje...");
        checkDatabase.close();
        return true;
    }

}

private void copyDB() throws IOException {

    InputStream inDBStream = context.getAssets().open(DBConstant.DB_NAME);
    String newDBPath = DBConstant.DB_PATH + DBConstant.DB_NAME;

    OutputStream outDBStream = new FileOutputStream(newDBPath);
    Log.i("copyDB", "Otevren outputstream s cestou k nove databazi");

    byte[] buffer = new byte[1024];
    int length;
    while ((length = inDBStream.read(buffer))>0){
        outDBStream.write(buffer, 0, length);
    }

    outDBStream.flush();
    outDBStream.close();
    inDBStream.close();
}

public void openDB() throws SQLException {
    String fullPath = DBConstant.DB_PATH + DBConstant.DB_NAME;
    if(sqliteDatabase!=null){
        if(sqliteDatabase.isOpen()){
            Log.i("openDB()", "Databaze je jiz otevrena");
        }
        else{
            sqliteDatabase = SQLiteDatabase.openDatabase(fullPath, null, SQLiteDatabase.OPEN_READONLY);
            Log.i("openDB()", "Databaze" + sqliteDatabase.getPath() + "otevrena");
        }
    }
    else{
        sqliteDatabase = SQLiteDatabase.openDatabase(fullPath, null, SQLiteDatabase.OPEN_READONLY);
        if(sqliteDatabase.isOpen()){
            Log.i("openDB()", "Databaze otevrena");
        }

    }
}
@Override
public void close() {

    if(sqliteDatabase!=null){
        sqliteDatabase.close();
        Log.i("close()", "Databaze zavrena");
    }
    super.close();

}

public SQLiteDatabase getSQLiteDatabase() {
    if(sqliteDatabase==null){
        Log.i("getSQLiteDatabase()","Problem, vraci sqliteDatabase = null");
    }
    else{
        Log.i("getSQLiteDatabase()","instance sqliteDatabase vracena bez problemu");
    }

    return sqliteDatabase;

}

AssyncTask类：

公共类OpenDatabaseTask扩展的AsyncTask {

public class OpenDatabaseTask extends AsyncTask {

private Context context;
private SQLiteDB sqliteDB;

public OpenDatabaseTask(Context context,SQLiteDB sqliteDB) {
    this.context = context;
    this.sqliteDB = sqliteDB;
}
@Override
protected Void doInBackground(Void... params) {
    publishProgress();

    try {
        sqliteDB.createDB();
    } catch (IOException e) {
        e.printStackTrace();
    }
    sqliteDB.openDB();

    return null;
}
@Override
protected void onProgressUpdate(Void...unused){
    Log.i(OpenDatabaseTask.class.toString(), "Spusteno vlakno");
}

}

和活动（仅重要部分）：

    private SQLiteDB sqliteDB;
    private SQLiteData sqliteData;
    private OpenDatabaseTask openDatabaseTask;

 @Override
 public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.navigatemenu);

        sqliteDB = new SQLiteDB(getApplicationContext(), sourceDatabaseName);
        openDatabaseTask = new OpenDatabaseTask(getApplicationContext(), sqliteDB);
        openDatabaseTask.execute();

    protected void onDestroy(){
        super.onDestroy();
        Log.i("onDestroy()", "Pokus o zavreni databaze");
            //here is the problem, database never closed
        sqliteDB.close();
    }
    protected void onStop(){
        super.onStop();
        Log.i("onStop()", "Pokus o zavreni databaze");
            //here is the problem, database never closed
        sqliteDB.close();
    }
    protected void onPause(){
        super.onPause();
    }
    protected void onResume(){
        super.onResume();
        //Log.i("onResume()", "Pokus o otevreni databaze");
    }
}

所以，当我尝试使用的close（）的方法来关闭数据库，sqliteDatabase总是空和数据库永远不会关闭。因此，数据库仍然打开，并调用后的onDestroy 异常发生。

So when I try use a close() method to closing database, sqliteDatabase is always null and database is never closed. So database is still opened and after calling onDestroy exception occurs.

感谢您的时间和抱歉，我的英语水平，我是捷克:)

Thank you for your time and sorry for my english, I'm czech :)

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