问题描述
我有一个用于字典应用程序的大型数据库。 我将该数据库从原始文件夹复制到了应用程序包的数据库路径。
public class DbHelper extends sqliteOpenHelper {
private sqliteDatabase mDataBase;
private static int DB_VERSION = 1;
private Context mContext;
private static String DB_PATH;
private static final String DATABASE_NAME = "offlinedictionary.db";
private static final String LOG_TAG = "DBHelper";
public DbHelper(@Nullable Context context) {
super(context,DATABASE_NAME,null,DB_VERSION);
Log.d(LOG_TAG,"DbHelper constructor");
mContext = context;
if (android.os.Build.VERSION.SDK_INT >= 4.2) {
DB_PATH = context.getApplicationInfo().dataDir + "/databases/";
} else {
DB_PATH = "/data/data/" + context.getPackageName() + "/databases/";
}
Log.d(LOG_TAG,"database path: "+DB_PATH);
}
public void createDataBase() throws IOException {
// If database not exists copy it from the assets
boolean mDataBaseExist = checkDataBase();
Log.d(LOG_TAG,"createDataBase: mDataBaseExist "+mDataBaseExist);
if (mDataBaseExist) {
// this.getReadableDatabase();
// this.close();
try {
// copy the database from assests
copyDataBase();
Log.e("DataBaseHelper","createDatabase database created");
} catch (IOException mIOException) {
throw new Error("Error copying DataBase");
}
}
}
private boolean checkDataBase() {
File dbFile = new File(DB_PATH + DATABASE_NAME);
//Log.v("dbFile",dbFile + " "+ dbFile.exists());
Log.d(LOG_TAG,"checkDataBase: dbFile "+dbFile.getName());
Log.d(LOG_TAG,"checkDataBase: dbFile.exists() "+dbFile.exists());
return dbFile.exists();
}
private void copyDataBase() throws IOException {
InputStream mInput = mContext.getResources().openRawResource(R.raw.offlinedictionary);
String outFileName = DB_PATH + DATABASE_NAME;
OutputStream mOutput = new FileOutputStream(outFileName);
Log.d(LOG_TAG,"copyDataBase: mInput "+mInput);
Log.d(LOG_TAG,"copyDataBase: outFileName "+outFileName);
Log.d(LOG_TAG,"copyDataBase: mOutput "+mOutput);
byte[] mBuffer = new byte[1024];
int mLength;
while ((mLength = mInput.read(mBuffer)) > 0) {
mOutput.write(mBuffer,mLength);
Log.d(LOG_TAG,"copyDataBase: mLength "+mLength);
}
Log.d(LOG_TAG,"copyDataBase: done ");
mOutput.flush();
mOutput.close();
mInput.close();
}
@Override
public void onCreate(sqliteDatabase db) {
try {
createDataBase();
} catch (IOException e) {
e.printstacktrace();
}
}
}
该数据库包含表“ worddictionary”。
但是当我查询该表时，出现错误，提示不存在该表。但是我在复制的数据库中看到该表及其内容存在。
public class LoadActivity extends AppCompatActivity {
private static final String LOG_TAG = "LoadActivity";
private DbHelper dbHelper;
private sqliteDatabase mDatabase;
private Context mContext;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_load);
Log.d(LOG_TAG,"Starting Load Activity");
mContext = getApplicationContext();
dbHelper = new DbHelper(this);
mDatabase = dbHelper.getWritableDatabase();
Log.d(LOG_TAG,"Call insertData");
insertData();
}
public void insertData(){
Log.d(LOG_TAG,"insertData");
InsertData fetchWordDetails = new InsertData();
fetchWordDetails.execute();
}
private class InsertData extends AsyncTask<Void,Void,Void> {
}
@Override
protected Void doInBackground(Void... voids) {
String wordQuery = "SELECT * FROM worddictionary;";
Cursor wordCursor = mDatabase.rawQuery(wordQuery,null);
int wordCount = wordCursor.getCount();
Log.d(LOG_TAG,"wod wordCount: "+wordCount);
}
}
谁能解释出什么问题了？
解决方法
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