E/Trace: error opening trace file: No such file or directory (2)
代码:
public static final String DATABASE_PATH = "/data/data/com.mycomp.myapp/databases/";
public static final String DATABASE_NAME = "database.db";
@Override
protected void onCreate(Bundle savedInstanceState) {
try {
copyDatabase(getApplicationContext());
} catch (IOException e) {
e.printStackTrace();
Log.d(TAG, "blad" + e.toString());
}
}
private void copyDatabase(Context context) throws IOException {
String outfilename = DATABASE_PATH + DATABASE_NAME;
InputStream myinput = context.getAssets().open("database.db");
OutputStream myoutput = new FileOutputStream(outfilename);
byte[] buffer = new byte[1024];
int length;
while ((length = myinput.read(buffer)) > 0) {
myoutput.write(buffer, 0, length);
}
myoutput.flush();
myoutput.close();
myinput.close();
}
答案 0 :(得分:2)
你可以尝试这个代码,然后请告诉我结果。 请务必检查所有文件名。
@Override
protected void onCreate(Bundle savedInstanceState) {
//.......
DatabaseHelper dbHelper = new DatabaseHelper(this);
dbHelper.createDatabase();
dbHelper.openDatabase();
// do stuff
Cursor data =dbHelper.Sample_use_of_helper();
dbHelper.close();
}
class DatabaseHelper extends SQLiteOpenHelper {
private static String DB_PATH = "/data/data/com.mycomp.myapp/databases/";
private static String DB_NAME = "database.db";
private SQLiteDatabase myDataBase;
private final Context myContext;
public DatabaseHelper (Context context) {
super(context, DB_NAME, null, 1);
this.myContext = context;
}
public void crateDatabase() throws IOException {
boolean vtVarMi = isDatabaseExist();
if (!vtVarMi) {
this.getReadableDatabase();
try {
copyDataBase();
} catch (IOException e) {
throw new Error("Error copying database");
}
}
}
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();
}
private boolean isDatabaseExist() {
SQLiteDatabase kontrol = null;
try {
String myPath = DB_PATH + DB_NAME;
kontrol = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);
} catch (SQLiteException e) {
kontrol = null;
}
if (kontrol != null) {
kontrol.close();
}
return kontrol != null ? true : false;
}
public void openDataBase() throws SQLException {
// Open the database
String myPath = DB_PATH + DB_NAME;
myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READWRITE);
}
public Cursor Sample_use_of_helper() {
return myDataBase.query("TABLE_NAME", null, null, null, null, null, null);
}
@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) {
}
}
答案 1 :(得分:0)
从 DB_NAME 和 .open(“database.db”)中删除 .db 扩展程序 它看起来很丑,但目前同样的事情对我有用.... 在安装新的apk之前,请为早期安装的apk做 清除数据
如果它不起作用,请提及您的数据库大小。