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我已经在谷歌商店有一个应用程序。我正在使用一个有 3 个表的内置数据库,并在第一次启动应用程序时复制它。现在我想升级到应用程序并添加另一个表。下面是我的代码。

public DataBaseHelper(Context context) 
{
    super(context, DB_NAME, null, 1);
    DB_PATH = "/data/data/" + context.getPackageName() + "/databases/";
    this.mContext = context;
}   

public void createDataBase() throws IOException
{
    //If database not exists copy it from the assets

    boolean mDataBaseExist = checkDataBase();
    if(!mDataBaseExist)
    {
        this.getReadableDatabase();
        this.close();
        try 
        {
            //Copy the database from assests
            copyDataBase();
            Log.e(TAG, "createDatabase database created");
        } 
        catch (IOException mIOException) 
        {
            throw new Error("ErrorCopyingDataBase");
        }
    }
}
    //Check that the database exists here: /data/data/your package/databases/Da Name
    private boolean checkDataBase()
    {
        File dbFile = new File(DB_PATH + DB_NAME);
        return dbFile.exists();
    }

    //Copy the database from assets
    private void copyDataBase() throws IOException
    {
        InputStream mInput = mContext.getAssets().open(DB_NAME);
        String outFileName = DB_PATH + DB_NAME;
        OutputStream mOutput = new FileOutputStream(outFileName);
        byte[] mBuffer = new byte[1024];
        int mLength;
        while ((mLength = mInput.read(mBuffer))>0)
        {
            mOutput.write(mBuffer, 0, mLength);
        }
        mOutput.flush();
        mOutput.close();
        mInput.close();
    }

    //Open the database, so we can query it
    public boolean openDataBase() throws SQLException
    {
        String mPath = DB_PATH + DB_NAME;
        //Log.v("mPath", mPath);
        mDataBase = SQLiteDatabase.openDatabase(mPath, null, SQLiteDatabase.CREATE_IF_NECESSARY);
        //mDataBase = SQLiteDatabase.openDatabase(mPath, null, SQLiteDatabase.NO_LOCALIZED_COLLATORS);
        return mDataBase != null;
    }

    @Override
    public synchronized void close() 
    {
        if(mDataBase != null)
            mDataBase.close();
        super.close();
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) 
    {
        Log.w(TAG, "Upgrading database from version " + oldVersion + " to "
                + newVersion + ", which will destroy all old data");
        String sql = "CREATE TABLE IF NOT EXISTS CKRecordings (" +
                "_id INTEGER PRIMARY KEY AUTOINCREMENT, " + 
                "name TEXT , filepath TEXT , creationDate TEXT)";
        db.execSQL(sql);
        db.execSQL("DROP TABLE IF EXISTS data");
        onCreate(db);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        // TODO Auto-generated method stub

    }

我想问几个问题。上面的代码没有升级。

现在,如果我是该应用程序的新用户,我是否必须编辑旧数据库并制作另一个 CKRecording 表并将其替换为放置在资产或以上代码中的当前数据库也适用于新用户?

4

1 回答 1

1
super(context, DB_NAME, null, 1);

在此语句中,最后一个参数是数据库版本。为新更新的 APK将其设置为 2 。因此现有用户可以有新添加的表或列。

在更新的 apk onUpgrade 将调用。在那里你可以从资产中复制数据库。但是现有用户会丢失数据..所以最好的选择是在数据库中动态添加表。

于 2013-01-09T14:03:08.253 回答