无法从资产中复制SQLite数据库

我尝试从资产目录复制SQLite数据库以便以后访问它。 但我做不到！

public class DatabaseAdapter { private static String DB_PATH = "/data/data/com.mypackage/databases/"; private static String DB_NAME = "database.sqlite"; private static String TABLE_NAME = "content_table"; private SQLiteDatabase database = null; private final Context context; public DatabaseAdapter(Context context){ this.context = context; } private void openDatabase() throws SQLiteException{ DatabaseHelper databaseHelper = new DatabaseHelper(context, DB_NAME); SQLiteDatabase db = null; if(!checkDatabase()){ try{ //Tried to create db before copying, so file should exist db = databaseHelper.getReadableDatabase(); db.close(); copyDatabase(); }catch(IOException exception){ Log.d("DatabaseAdapter", "Error copying DB: "+exception); } } database = SQLiteDatabase.openDatabase(DB_PATH+DB_NAME, null, SQLiteDatabase.OPEN_READONLY); } private void closeDatabase(){ database.close(); } public ArrayList queryCategories(){ try{ openDatabase(); }catch(SQLiteException exc){ exc.printStackTrace(); } //............................. return result; } private boolean checkDatabase(){ File dbFile = new File(DB_PATH + DB_NAME); return dbFile.exists(); } private void copyDatabase() throws IOException{ InputStream inputStream = context.getAssets().open(DB_NAME); String outFileName = DB_PATH + DB_NAME; OutputStream outputStream = new FileOutputStream(outFileName); byte[] buffer = new byte[1024]; int length; while ((length = inputStream.read(buffer))>0){ outputStream.write(buffer, 0, length); } outputStream.flush(); outputStream.close(); inputStream.close(); } } 

DatabaseHelper很简单：

 ublic class DatabaseHelper extends SQLiteOpenHelper { public DatabaseHelper(Context context, String name){ super(context, name, null, 1); } @Override public void onCreate(SQLiteDatabase arg0) { // TODO Auto-generated method stub } @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { // TODO Auto-generated method stub } } 

尝试了一切！ 我试着玩延伸！ 但我仍然收到错误：复制DB时出错： java.io.FileNotFoundException: /data/data/com.mypackage/databases/database.sqlite (No such file or directory)

我检查了模拟器，我的文件在那里，所以我应该能够写到它！ 请帮忙！ 这让我疯了！

UPD我试着将它放在SD卡上，但它确实有用。 但仍然无法得到为什么我不能把它写到app数据文件夹。

Answer 1

我使用这个助手并且工作正常：

 public class DBHelper extends SQLiteOpenHelper{ private final static String DB_PATH = "/data/data/[YOUR PACKAGE HERE]/databases/"; String dbName; Context context; File dbFile; public DBHelper(Context context, String dbName, CursorFactory factory, int version) { super(context, dbName, factory, version); this.context = context; this.dbName = dbName; dbFile= new File(DB_PATH + dbName); } @Override public synchronized SQLiteDatabase getWritableDatabase() { if(!dbFile.exists()){ SQLiteDatabase db = super.getWritableDatabase(); copyDataBase(db.getPath()); } return super.getWritableDatabase(); } @Override public synchronized SQLiteDatabase getReadableDatabase() { if(!dbFile.exists()){ SQLiteDatabase db = super.getReadableDatabase(); copyDataBase(db.getPath()); } return super.getReadableDatabase(); } @Override public void onCreate(SQLiteDatabase db) {} @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {} private void copyDataBase(String dbPath){ try{ InputStream assestDB = context.getAssets().open("databases/"+dbName); OutputStream appDB = new FileOutputStream(dbPath,false); byte[] buffer = new byte[1024]; int length; while ((length = assestDB.read(buffer)) > 0) { appDB.write(buffer, 0, length); } appDB.flush(); appDB.close(); assestDB.close(); }catch(IOException e){ e.printStackTrace(); } } } 

考虑到数据库的文件扩展名是.db ，我的数据库是资产/数据库/

Answer 2

我有同样的问题，我用另一种方法修复了它。 一开始，我按照每个人的说法声明了数据库路径：

 dbPath="data/data//databases/data.db" 

这是一条确切的道路 ，没有错。 但是当我尝试打开OutPutFileStream来复制数据库时，它总是会失败。 我不知道为什么。 然后，我改变了打开数据库的方式，如下所示：

 dbPath = context.getDatabasePath(dbName); OutputStream myOutput = new FileOutputStream(dbPath.getAbsolutePath()); 

问题已经解决了。 太惊喜了。

希望这可以帮助。

Answer 3

 public static void copyDatabase(final Context ctx, String dbName) { if (ctx != null) { File f = ctx.getDatabasePath(dbName); if (!f.exists()) { // check databases exists if (!f.getParentFile().exists()) f.getParentFile().mkdir(); try { InputStream in = ctx.getAssets().open(dbName); OutputStream out = new FileOutputStream(f.getAbsolutePath()); byte[] buffer = new byte[1024]; int length; while ((length = in.read(buffer)) > 0) { out.write(buffer, 0, length); } in.close(); out.close(); Logger.i("Database copy successed! " + f.getPath()); } catch (Exception ex) { Logger.e(ex); } } } } 

Answer 4

请检查OutputStream之前的数据库文件夹。

喜欢这个，

 File databaseFile = new File(context.getFilesDir().getAbsolutePath() .replace("files", "databases")); // check if databases folder exists, if not create it. if (!databaseFile.exists()){ databaseFile.mkdir(); }