Android 项目未添加到数据库中
我有一个sqlite数据库，它作为一项资产与我的应用程序捆绑在一起，在我的应用程序第一次启动时，数据库将用下面的代码复制到设备上Android 项目未添加到数据库中,android,sqlite,Android,Sqlite,我有一个sqlite数据库，它作为一项资产与我的应用程序捆绑在一起，在我的应用程序第一次启动时，数据库将用下面的代码复制到设备上 public class DataBaseHelper extends SQLiteOpenHelper { // The Android's default system path of your application database. private static String DB_PATH = "/data/data/my.apps.na
public class DataBaseHelper extends SQLiteOpenHelper {
// The Android's default system path of your application database.
private static String DB_PATH = "/data/data/my.apps.namespace/databases/";
private static String DB_NAME = "DB.sqlite";
private SQLiteDatabase myDataBase;
private final Context myContext;
public DataBaseHelper(Context context) {
super(context, DB_NAME, null, 1);
this.myContext = context;
}
/**
* Creates a empty database on the system and rewrites it with your own
* database.
* */
public void createDataBase() throws IOException {
boolean dbExist = checkDataBase();
if (dbExist) {
// do nothing - database already exist
} else {
// By calling this method and empty database will be created into
// the default system path
// of your application so we are gonna be able to overwrite that
// database with our database.
this.getReadableDatabase();
try {
copyDataBase();
} catch (IOException e) {
throw new Error("Error copying database");
}
}
}
/**
* Check if the database already exist to avoid re-copying the file each
* time you open the application.
*
* @return true if it exists, false if it doesn't
*/
private boolean checkDataBase() {
SQLiteDatabase checkDB = null;
try {
String myPath = DB_PATH + DB_NAME;
checkDB = SQLiteDatabase.openDatabase(myPath, null,
SQLiteDatabase.OPEN_READONLY);
} catch (SQLiteException e) {
// database does't exist yet.
}
if (checkDB != null) {
checkDB.close();
}
return checkDB != null ? true : false;
}
/**
* Copies your database from your local assets-folder to the just created
* empty database in the system folder, from where it can be accessed and
* handled. This is done by transfering bytestream.
* */
private void copyDataBase() throws IOException {
// Open your local db as the input stream
InputStream myInput = myContext.getAssets().open(DB_NAME);
// Path to the just created empty db
String outFileName = DB_PATH + DB_NAME;
// Open the empty db as the output stream
OutputStream myOutput = new FileOutputStream(outFileName);
// transfer bytes from the inputfile to the outputfile
byte[] buffer = new byte[1024];
int length;
while ((length = myInput.read(buffer)) > 0) {
myOutput.write(buffer, 0, length);
}
// Close the streams
myOutput.flush();
myOutput.close();
myInput.close();
}
public void openDataBase() throws SQLException {
// Open the database
String myPath = DB_PATH + DB_NAME;
myDataBase = SQLiteDatabase.openDatabase(myPath, null,
SQLiteDatabase.OPEN_READWRITE);
}
@Override
public synchronized void close() {
if (myDataBase != null)
myDataBase.close();
super.close();
}
@Override
public void onCreate(SQLiteDatabase db) {
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
....
}
public Category getCategory(int id) {
openDataBase();
Cursor cursor = myDataBase.rawQuery(
"select * from categories where _id = " + id, null);
cursor.moveToFirst();
while (!cursor.isAfterLast()) {
Category cat = cursorToCategory(cursor);
return cat;
}
// make sure to close the cursor
cursor.close();
return null;
}
public void addToWordBank(Word currentWord) {
openDataBase();
myDataBase.rawQuery("INSERT into wordBank(english) VALUES(?) ",
new String[] { currentWord.english });
}
public boolean wordBankHas(Word currentWord) {
openDataBase();
Cursor cursor = myDataBase.rawQuery(
"select * from wordBank where english =? ",
new String[] { currentWord.english });
if (cursor.getCount() <= 0) {
return false;
}
return true;
}