我想preloaded database在我的应用程序中使用意味着在安装 apk 时尝试获取数据库，以便可以使用已经保存在其中的数据。我将“ingredients.db”
文件复制到资产文件夹中。并使用以下代码，但这会得到错误“从资源文件复制数据库时出现问题”
我怎么解决这个问题？请给我建议可能的方法
我的数据库助手类是这样的
class IngredientHelper extends SQLiteOpenHelper {
private static final String DATABASE_PATH = "/data/data/com.example.preloadeddatabase/databases/";
private static final String DATABASE_NAME = "ingredients.db";
private static final String TABLE_NAME = "Ingredients";
private static final String COLUMN_ID = "_id";
private static final String COLUMN_TITLE = "ingredient_name";
private static final int SCHEMA_VERSION = 1;
public SQLiteDatabase dbSqlite;
private final Context myContext;
public IngredientHelper(Context context) {
super(context, DATABASE_NAME, null, SCHEMA_VERSION);
this.myContext = context;
}
@Override
public void onCreate(SQLiteDatabase db) {
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
public void createDatabase() {
createDB();
}
public void createDB() {
boolean dbExist = DbExists();
if (!dbExist) {
this.getReadableDatabase();
copyDataBase();
}
}
private boolean DbExists() {
SQLiteDatabase db = null;
try {
String databasePath = DATABASE_PATH + DATABASE_NAME;
db = SQLiteDatabase.openDatabase(databasePath, null,
SQLiteDatabase.OPEN_READWRITE);
db.setLocale(Locale.getDefault());
db.setLockingEnabled(true);
db.setVersion(1);
}
catch (SQLiteException e) {
Log.e("SqlHelper", "Database Not Found");
}
if (db != null) {
db.close();
}
return db != null ? true : false;
}
private void copyDataBase() {
InputStream iStream = null;
OutputStream oStream = null;
String outFilePath = DATABASE_PATH + DATABASE_NAME;
try {
iStream = myContext.getAssets().open(DATABASE_NAME);
oStream = new FileOutputStream(outFilePath);
byte[] buffer = new byte[2048];
int length;
while ((length = iStream.read(buffer)) > 0) {
oStream.write(buffer, 0, length);
}
oStream.flush();
oStream.close();
iStream.close();
}
catch (IOException e) {
throw new Error("Problem Copying Database From Resource File");
}
}
public void openDatabase() throws SQLException {
String myPath = DATABASE_PATH + DATABASE_NAME;
dbSqlite = SQLiteDatabase.openDatabase(myPath, null,
SQLiteDatabase.OPEN_READWRITE);
}
@Override
public synchronized void close() {
if (dbSqlite != null) {
dbSqlite.close();
}
super.close();
}
public Cursor getCursor() {
SQLiteQueryBuilder queryBuilder = new SQLiteQueryBuilder();
queryBuilder.setTables(TABLE_NAME);
String[] asColumnsToReturn = new String[] { COLUMN_ID, COLUMN_TITLE };
Cursor mCursor = queryBuilder.query(dbSqlite, asColumnsToReturn,
null, null, null, null, "ingredient_name ASC");
return mCursor;
}
public String getName(Cursor c) {
return (c.getString(1));
}