數據庫未在OnePlus Two中正確復制

Question

我正在創建一個Android應用程序，我正在使用sqlite數據庫。 因為我已經在項目的資產文件夾中放置了一個sqlite文件，我在使用下面的代碼首次執行應用程序時將此文件復制到手機中。

 private void copyDataBase() throws IOException {
    new File(DB_PATH).mkdirs();
    InputStream myInput = appContext.getAssets().open(DB_NAME);
    String outFileName = DB_PATH + DB_NAME;
    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();
}

但我得到了這個錯誤。

 09-21 18:03:56.841: E/SQLiteLog(7850): (1) no such table: tbl_player

但是這個表存在於資產文件中。 所以我使用這種方法從手機中獲取數據庫文件。

public static void exportDB(String databaseName, Context context) {
    try {
        File sd = Environment.getExternalStorageDirectory();
        File data = Environment.getDataDirectory();

        if (sd.canWrite()) {
            String currentDBPath = "//data//" + context.getPackageName()
                    + "//databases//" + databaseName + "";
            String backupDBPath = "sensor_game.db";
            File currentDB = new File(data, currentDBPath);
            File backupDB = new File(sd, backupDBPath);

            if (currentDB.exists()) {
                FileChannel src = new FileInputStream(currentDB)
                        .getChannel();
                FileChannel dst = new FileOutputStream(backupDB)
                        .getChannel();
                dst.transferFrom(src, 0, src.size());
                src.close();
                dst.close();
            }
        }

    } catch (Exception e) {

    }
}

我發現獲取的數據庫文件中沒有表。

注意：此問題僅在OnePlus Two發生，並且在Nexus 4 ， Htc 820 ， Moto E ， Galaxy Quottro Galxy S3和Galaxy Quottro

Answer 1

數據庫路徑在不同設備中可能不同。 您需要使用Context.getDatabasePath(String)才能獲取數據庫路徑。

例如

File backupDB = context.getDatabasePath(backupDBPath);

Answer 2

經過長時間的嘗試和搜索后，我不得不假設OP2制造中應該有一個錯誤，因為它在所有其他設備中都能正常工作。

我改變了使用查詢創建數據庫的方法，而不是從資產中復制數據庫文件。 像下面的代碼

import java.io.File;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;

public class MySQLiteHelper extends SQLiteOpenHelper implements DBConstants {

private static MySQLiteHelper mInstance = null;
private SQLiteDatabase myDataBase;
private static String DB_PATH = "";

public MySQLiteHelper(Context context) {
    super(context, DATABASE_NAME, null, DATABASE_VERSION);
    try {
        if (checkDataBase())
            openDataBase();
        else
            myDataBase = this.getReadableDatabase();
    } catch (Exception e) {
    }
}

public static MySQLiteHelper instance(Context context) {

    File outFile = context.getDatabasePath(DATABASE_NAME);
    DB_PATH = outFile.getPath();

    if (mInstance == null) {
        mInstance = new MySQLiteHelper(context);
    }

    return mInstance;
}

private void openDataBase() throws Exception {
    try {
        myDataBase = SQLiteDatabase.openDatabase(DB_PATH, null,
                SQLiteDatabase.OPEN_READWRITE);
    } catch (SQLException e) {
        // TODO: handle exception
    }
}

private boolean checkDataBase() {
    SQLiteDatabase checkDB = null;
    try {
        checkDB = SQLiteDatabase.openDatabase(DB_PATH, null,
                SQLiteDatabase.OPEN_READONLY);

    } catch (SQLiteException e) {
        /** database does't exist yet. */
    } catch (Exception e) {
    }
    if (checkDB != null) {
        checkDB.close();
    }
    return checkDB != null ? true : false;
}

@Override
public void onCreate(SQLiteDatabase db) {

    Log.v("log_tag", "onCreate");
    myDataBase = db;

    // creating a sample table
    String CREATE_DEVICE_TABLE = "CREATE TABLE " + DEVICE + " ("
            + KEY_DEVICEID + " TEXT, " + KEY_OPERATOR + " TEXT, "
            + KEY_DEVICENAME + " TEXT, " + KEY_DEVICETOTALMEMORY
            + " INTEGER, " + KEY_SCREENWIDTH + " INTEGER, "
            + KEY_SCREENHEIGHT + " INTEGER, " + KEY_OPERATINGSYSTEM
            + " TEXT)";

    db.execSQL(CREATE_DEVICE_TABLE);

    // other tables also can be created from here.
}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    db.execSQL("DROP TABLE IF EXISTS " + DEVICE);

    // Create tables again (as per requirement)
    this.onCreate(db);
}

public Cursor rawQuery(String qry) {
    return myDataBase.rawQuery(qry, null);
}

public long insert(String tableName, ContentValues cv) {
    return myDataBase.insert(tableName, null, cv);
}

public void insertWithOnConflict(String tableName, ContentValues cv,
        int flag) {
    myDataBase.insertWithOnConflict(tableName, null, cv, flag);

}

public long update(String tableName, ContentValues cv, String whereClose) {
    return myDataBase.update(tableName, cv, whereClose, null);

}

public int deleteData(String table_name, String whereClause) {
    return (int) myDataBase.delete(table_name, whereClause, null);
}

}

它對我有用

謝謝！

Answer 3

我找到了解決方案，我使用了以下功能：

public void createDb() {
        boolean dbExist = checkDataBase();

        if (dbExist) {
            // do nothing - database already exist
        } else {
            // call close() for properly copy database file
            this.getReadableDatabase().close();
            try {
                copyDataBase();
            } catch (IOException e) {
                e.printStackTrace();
                throw new Error("Error copying database");
            }
        }
    }

根據這篇文章，我們需要調用close() ，你也可以將數據庫推送到Oneplus兩個設備。