android - 关于未在 android sqlite 中调用的升级方法

Question

我在我的应用程序中使用预填充的 sqlite 数据库，我试图在我的 android 应用程序中更新我的数据库，但是当我增加版本号时 onUpgrade 方法没有被调用。我试过谷歌搜索，在 stackoverflow 上搜索但没有任何帮助。如果我在构造函数中取消注释 this.getReadableDatabase()，则会调用 onUpgrade 方法，但我无法查询数据并返回错误。

这是我的代码。

     public class DatabaseHelper extends SQLiteOpenHelper {

        private  static final String DB_NAME = "dictionary.db";
        private static final int DB_VERSION = 1;
        private String DB_PATH = null;
        private  static final String TABLE_DICTIONARY = "dictionary";
        private  static final String TABLE_BOOKMARK= "bookmark";
        private static final String COL_ID = "id";
        private static final String COL_WORD = "word";
        private static final String COL_DEFINITION = "definition";
        private Context mcontext;
        private SQLiteDatabase mDatabase;


        public DatabaseHelper( Context context) {
            super(context, DB_NAME, null, DB_VERSION);
            this.mcontext = context;
            this.DB_PATH = "/data/data/" + context.getPackageName() + "/" + "databases/";
            //this.getReadableDatabase();
        }

        public void createDataBase() throws IOException {

            boolean dbExist = checkDataBase();
            if (!dbExist) {
                this.getReadableDatabase();
                try {
                    mcontext.deleteDatabase(DB_NAME);
                    copyDataBase();
                } catch (IOException e) {
                    throw new Error("Error copying database");
                }
            }
        }

        public boolean checkDataBase() {
            SQLiteDatabase checkDB = null;
            try {
                String myPath = DB_PATH + DB_NAME;
                checkDB = SQ

LiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);
        } catch (SQLiteException e) {
            e.printStackTrace();
        }
        if (checkDB != null) {
            checkDB.close();
        }
        return checkDB != null ? true : false;
    }

    private void copyDataBase() throws IOException {

        InputStream myInput = mcontext.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();
    }

    public void openDatabase() throws SQLException {
        String myPath = DB_PATH + DB_NAME;
        mDatabase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READWRITE);
    }

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

         @Override
    public void onCreate(SQLiteDatabase db) {

    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

        if (newVersion > oldVersion) {
            try {
                copyDataBase();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

        Log.d(TAG, "onUpgrade:called ");
    }
}

Answer 1

我认为您的问题是您没有使用 SQLiteOpenHelper 的方法之一(getWritableDatabse 或 getReadableDatabase)来打开数据库。

而是使用SQLiteDatabase 的OPEN 方法。哪个不进行版本检查和设置。

If I uncomment this.getReadableDatabase() in my constructor the onUpgrade method gets called but I can't query the data and returns error.

引入 getReadableDatabase，然后进行检查并尝试复制较新版本，但旧版本已打开，因此您可能会因此发生冲突。

您可能会找到问题的答案 Which methods can be used to manage differing versions of pre-existing databases?有帮助(也许是第二个)。

工作示例

以下工作示例使用链接答案中的代码，但基于问题中的代码和数据库(可确定)。

核心底层类是 DatabaseAssetHandler.java，它包括许多用于检查和复制数据库的静态方法，所有这些方法都以文件而不是 SQLite 数据库的形式出现。

SQLiteOpenHelper 的子类，基于问题的 DatabaseHelper.java 类，但利用 DatabaseAssethandler 方法再次检查编码版本和数据库文件版本(不需要使用 onUpgrade 方法以及onCreate 方法)

最后，该示例包含一个 Activity ，MainActivity.java 您通常会发现。此类另外从数据库中提取所有行并将 Cursor 转储到日志中。

DatabaseAssetManager.java

public class DatabaseAssetHandler {

    static final String[] tempfiles = new String[]{"-journal","-wal","-shm"}; // temporary files to rename
    public static final String backup = "-backup"; //value to be appended to file name when renaming (psuedo delete)
    public static final  int OUCH = -666666666;

    /**
     * Check if the database already exists. NOTE will create the databases folder is it doesn't exist
     * @return true if it exists, false if it doesn't
     */
    public static boolean checkDataBase(Context context, String dbname) {

        File db = new File(context.getDatabasePath(dbname).getPath()); //Get the file name of the database
        Log.d("DBPATH","DB Path is " + db.getPath()); //TODO remove if publish App
        if (db.exists()) return true; // If it exists then return doing nothing

        // Get the parent (directory in which the database file would be)
        File dbdir = db.getParentFile();
        // If the directory does not exits then make the directory (and higher level directories)
        if (!dbdir.exists()) {
            db.getParentFile().mkdirs();
            dbdir.mkdirs();
        }
        return false;
    }

    /**
     * Copy database file from the assets folder
     * (long version caters for asset file name being different to the database name)
     * @param context           Context is needed to get the applicable package
     * @param dbname            name of the database file
     * @param assetfilename     name of the asset file
     * @param deleteExistingDB  true if an existing database file should be deleted
     *                              note will delete journal and wal files
     *                              note doen't actually delete the files rater it renames
     *                              the files by appended -backup to the file name
     *                              SEE/USE clearForceBackups below to delete the renamed files
     */
    public static void copyDataBase(Context context, String dbname, String assetfilename, boolean deleteExistingDB, int version) {

        checkpointIfWALEnabled(context,dbname);
        final String TAG = "COPYDATABASE";
        int stage = 0, buffer_size = 4096, blocks_copied = 0, bytes_copied = 0;
        File f = new File(context.getDatabasePath(dbname).toString());
        InputStream is;
        OutputStream os;

        /**
         * If forcing then effectively delete (rename) current database files
         */
        if (deleteExistingDB) {
            f.renameTo(context.getDatabasePath(dbname + backup));
            for (String s: tempfiles) {
                File tmpf = new File(context.getDatabasePath(dbname + s).toString());
                if (tmpf.exists()) {
                    tmpf.renameTo(context.getDatabasePath(dbname + s + backup));
                }
            }
        }

        //Open your local db as the input stream
        Log.d(TAG,"Initiated Copy of the database file " + assetfilename + " from the assets folder."); //TODO remove if publishing
        try {
            is = context.getAssets().open(assetfilename); // Open the Asset file
            stage++;
            Log.d(TAG, "Asset file " + assetfilename + " found so attmepting to copy to " + f.getPath()); //TODO remove if publishing

            os = new FileOutputStream(f);
            stage++;
            //transfer bytes from the inputfile to the outputfile
            byte[] buffer = new byte[buffer_size];
            int length;
            while ((length = is.read(buffer)) > 0) {
                blocks_copied++;
                Log.d(TAG, "Attempting copy of block " + String.valueOf(blocks_copied) + " which has " + String.valueOf(length) + " bytes."); //TODO remove if publishing
                os.write(buffer, 0, length);
                bytes_copied += length;
            }
            stage++;
            Log.d(TAG,
                    "Finished copying Database " + dbname +
                            " from the assets folder, to  " + f.getPath() +
                            String.valueOf(bytes_copied) + "were copied, in " +
                            String.valueOf(blocks_copied) + " blocks of size " +
                            String.valueOf(buffer_size) + "."
            ); //TODO remove if publishing
            //Close the streams
            os.flush();
            stage++;
            os.close();
            stage++;
            is.close();
            Log.d(TAG, "All Streams have been flushed and closed.");
            if (version > 0) {
                setVersion(context,dbname,version);
            }
        } catch (IOException e) {
            String exception_message = "";
            e.printStackTrace();
            switch (stage) {
                case 0:
                    exception_message = "Error trying to open the asset " + dbname;
                    break;
                case 1:
                    exception_message = "Error opening Database file for output, path is " + f.getPath();
                    break;
                case 2:
                    exception_message = "Error flushing written database file " + f.getPath();
                    break;
                case 3:
                    exception_message = "Error closing written database file " + f.getPath();
                    break;
                case 4:
                    exception_message = "Error closing asset file " + f.getPath();

            }
            throw new RuntimeException("Unable to copy the database from the asset folder." + exception_message + " see starck-trace above.");
        }
    }

    /**
     * Copy the databsse from the assets folder where asset name and dbname are the same
     * @param context
     * @param dbname
     * @param deleteExistingDB
     */
    public static void copyDataBase(Context context, String dbname, boolean deleteExistingDB, int version) {
        copyDataBase(context, dbname,dbname,deleteExistingDB, version);
    }

    /**
     * Get the SQLite_user_vesrion from the DB in the asset folder
     *
     * @param context           needed to get the appropriate package assets
     * @param assetfilename     the name of the asset file (assumes/requires name matches database)
     * @return                  the version number as stored in the asset DB
     */
    public static int getVersionFromDBInAssetFolder(Context context, String assetfilename) {
        InputStream is;
        try {
            is = context.getAssets().open(assetfilename);
        } catch (IOException e) {
            return OUCH;
        }
        return getDBVersionFromInputStream(is);
    }

    /**
     * Get the version from the database itself without opening the database as an SQliteDatabase
     * @param context   Needed to ascertain package
     * @param dbname    the name of the dataabase
     * @return          the version number extracted
     */
    public static int getVersionFromDBFile(Context context, String dbname) {
        InputStream is;
        try {
            is = new FileInputStream(new File(context.getDatabasePath(dbname).toString()));
        } catch (IOException e) {
            return OUCH;
        }
        return getDBVersionFromInputStream(is);
    }

    /**
     * Get the Database Version (user_version) from an inputstream
     *  Note the inputstream is closed
     * @param is    The Inputstream
     * @return      The extracted version number
     */
    private static int getDBVersionFromInputStream(InputStream is) {
        int rv = -1, dbversion_offset = 60, dbversion_length = 4 ;
        byte[] dbfileheader = new byte[64];
        byte[] dbversion = new byte[4];
        try {
            is.read(dbfileheader);
            is.close();
        } catch (IOException e) {
            e.printStackTrace();
            return rv;
        }

        for (int i = 0; i < dbversion_length; i++ ) {
            dbversion[i] = dbfileheader[dbversion_offset + i];
        }
        return ByteBuffer.wrap(dbversion).getInt();
    }

    /**
     * Check to see if the asset file exists
     *
     * @param context           needed to get the appropriate package
     * @param assetfilename     the name of the asset file to check
     * @return                  true if the asset file exists, else false
     */
    public static boolean ifAssetFileExists(Context context, String assetfilename) {
        try {
            context.getAssets().open(assetfilename);
        } catch (IOException e) {
            return false;
        }
        return true;
    }


    /**
     * Delete the backup
     * @param context
     * @param dbname
     */
    public static void clearForceBackups(Context context, String dbname) {
        String[] fulllist = new String[tempfiles.length + 1];

        for (int i = 0;i < tempfiles.length; i++) {
            fulllist[i] = tempfiles[i];
        }
        fulllist[tempfiles.length] = ""; // Add "" so database file backup is also deleted
        for (String s: fulllist) {
            File tmpf = new File(context.getDatabasePath(dbname + s + backup).toString());
            if (tmpf.exists()) {
                tmpf.delete();
            }
        }
    }

    /**
     *
     * @param context   The context so that the respective package is used
     * @param dbname    The name of the database (the old will have -backup appended)
     * @param table     The table from which to copy the data
     */
    public static void restoreTable(Context context, String dbname, String table) {
        ContentValues cv = new ContentValues();
        SQLiteDatabase dbnew = SQLiteDatabase.openDatabase(context.getDatabasePath(dbname).toString(), null,SQLiteDatabase.OPEN_READWRITE);
        SQLiteDatabase dbold = SQLiteDatabase.openDatabase(context.getDatabasePath(dbname + backup).toString(),null,SQLiteDatabase.OPEN_READONLY);
        Cursor csr = dbold.query(table,null,null,null,null,null,null);
        dbnew.beginTransaction();
        while (csr.moveToNext()) {
            cv.clear();
            int offset = 0;
            for (String column: csr.getColumnNames()) {
                switch (csr.getType(offset++)){
                    case Cursor.FIELD_TYPE_NULL:
                        break;
                    case Cursor.FIELD_TYPE_INTEGER:
                        cv.put(column,csr.getLong(csr.getColumnIndex(column)));
                        break;
                    case Cursor.FIELD_TYPE_FLOAT:
                        cv.put(column,csr.getFloat(csr.getColumnIndex(column)));
                        break;
                    case Cursor.FIELD_TYPE_STRING:
                        cv.put(column,csr.getString(csr.getColumnIndex(column)));
                        break;
                    case Cursor.FIELD_TYPE_BLOB:
                        cv.put(column,csr.getBlob(csr.getColumnIndex(column)));
                }
            }
            dbnew.insert(DatabaseHelper.TABLE_BOOKMARK,null,cv);
        }
        dbnew.setTransactionSuccessful();
        dbnew.endTransaction();
        csr.close();
        dbnew.close();
        dbold.close();
    }

    private static void checkpointIfWALEnabled(Context context, String dbname) {
        final String TAG = "WALCHKPNT";
        Cursor csr;
        int wal_busy = -99, wal_log = -99, wal_checkpointed = -99;
        if (!new File(context.getDatabasePath(dbname).getPath()).exists()) {
            return;
        }
        SQLiteDatabase db = SQLiteDatabase.openDatabase(context.getDatabasePath(dbname).getPath(),null,SQLiteDatabase.OPEN_READWRITE);
        csr = db.rawQuery("PRAGMA journal_mode",null);
        if (csr.moveToFirst()) {
            String mode = csr.getString(0);
            //Log.d(TAG, "Mode is " + mode);
            if (mode.toLowerCase().equals("wal")) {
                csr = db.rawQuery("PRAGMA wal_checkpoint",null);
                if (csr.moveToFirst()) {
                    wal_busy = csr.getInt(0);
                    wal_log = csr.getInt(1);
                    wal_checkpointed = csr.getInt(2);
                }
                //Log.d(TAG,"Checkpoint pre checkpointing Busy = " + String.valueOf(wal_busy) + " LOG = " + String.valueOf(wal_log) + " CHECKPOINTED = " + String.valueOf(wal_checkpointed) );
                csr = db.rawQuery("PRAGMA wal_checkpoint(TRUNCATE)",null);
                csr.getCount();
                csr = db.rawQuery("PRAGMA wal_checkpoint",null);
                if (csr.moveToFirst()) {
                    wal_busy = csr.getInt(0);
                    wal_log = csr.getInt(1);
                    wal_checkpointed = csr.getInt(2);
                }
                //Log.d(TAG,"Checkpoint post checkpointing Busy = " + String.valueOf(wal_busy) + " LOG = " + String.valueOf(wal_log) + " CHECKPOINTED = " + String.valueOf(wal_checkpointed) );
            }
        }
        csr.close();
        db.close();
    }

    private static void setVersion(Context context, String dbname, int version) {
        SQLiteDatabase db = SQLiteDatabase.openDatabase(context.getDatabasePath(dbname).getPath(),null,SQLiteDatabase.OPEN_READWRITE);
        db.setVersion(version);
        db.close();

    }
}

• 请注意，并非所有方法都被使用。
• 注释已修改 (2019-05-08)，以在 Assets 文件副本调用新的 setVersion 方法后专门设置版本号。
• 注释已修改 (2019-05-08) 以在复制之前调用新的 checkpointIfWALEnabled 方法，以便为数据库设置检查点。

数据库助手.java

public class DatabaseHelper extends SQLiteOpenHelper {

    private  static final String DB_NAME = "dictionary.db";
    private static final int DB_VERSION = 1;
    //private String DB_PATH = null; //<<<<<<<<<< NOT NEEDED
    public   static final String TABLE_DICTIONARY = "dictionary";
    public   static final String TABLE_BOOKMARK= "bookmark";
    public static final String COL_ID = "id";
    public static final String COL_WORD = "word";
    public static final String COL_DEFINITION = "definition";
    public Context mcontext;
    public SQLiteDatabase mDatabase;

    public DatabaseHelper(Context context) {
        super(context, DB_NAME, null, DB_VERSION);
        this.mcontext = context;
        Log.d("DBVERSION","The Database Version (as hard coded) is " + String.valueOf(DB_VERSION));

        int dbversion = DatabaseAssetHandler.getVersionFromDBFile(context,DB_NAME);
        Log.d("DBVERSION","The Database Version (as per the database file) is " + String.valueOf(dbversion));

        // Copy the Database if no database exists
        if (!DatabaseAssetHandler.checkDataBase(context,DB_NAME)) {
            DatabaseAssetHandler.copyDataBase(context,DB_NAME,true,DB_VERSION);
        } else {
            if (DB_VERSION > dbversion && DatabaseAssetHandler.checkDataBase(context, DB_NAME)) {
                DatabaseAssetHandler.copyDataBase(context, DB_NAME, true,DB_VERSION);
                DatabaseAssetHandler.clearForceBackups(context, DB_NAME); // Clear the backups
            }
        }
        mDatabase = this.getWritableDatabase(); //<<<<<<<<<<<<<
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    }

    public void openDatabase() throws SQLException {
        mDatabase = this.getWritableDatabase();
    }

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

- 注释修改 (2019-05-08) 以将版本号传递给 copyDatabase 方法。

主 Activity .java

public class MainActivity extends AppCompatActivity {

    DatabaseHelper mDBHlpr;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mDBHlpr = new DatabaseHelper(this);
        Cursor csr = mDBHlpr.getWritableDatabase().query(
                DatabaseHelper.TABLE_DICTIONARY,
                null,null,null,null,null,null
        );
        DatabaseUtils.dumpCursor(csr);
        csr.close();
    }
}

结果

首先使用外部工具在字典表中创建了一个包含 2 行的数据库，并将其复制到 Assets 文件夹中。

运行 1.

第一次运行，从 assets 文件夹中复制数据库，结果日志中包含:-

04-17 19:24:54.249 3233-3233/m.example.so55711282dictionary D/DBVERSION: The Database Version (as hard coded) is 1
04-17 19:24:54.249 3233-3233/m.example.so55711282dictionary D/DBVERSION: The Database Version (as per the database file) is -666666666
04-17 19:24:54.249 3233-3233/m.example.so55711282dictionary D/DBPATH: DB Path is /data/data/m.example.so55711282dictionary/databases/dictionary.db
04-17 19:24:54.250 3233-3233/m.example.so55711282dictionary D/COPYDATABASE: Initiated Copy of the database file dictionary.db from the assets folder.
04-17 19:24:54.251 3233-3233/m.example.so55711282dictionary D/COPYDATABASE: Asset file dictionary.db found so attmepting to copy to /data/data/m.example.so55711282dictionary/databases/dictionary.db
04-17 19:24:54.251 3233-3233/m.example.so55711282dictionary D/COPYDATABASE: Attempting copy of block 1 which has 4096 bytes.
04-17 19:24:54.251 3233-3233/m.example.so55711282dictionary D/COPYDATABASE: Attempting copy of block 2 which has 4096 bytes.
04-17 19:24:54.251 3233-3233/m.example.so55711282dictionary D/COPYDATABASE: Attempting copy of block 3 which has 4096 bytes.
04-17 19:24:54.251 3233-3233/m.example.so55711282dictionary D/COPYDATABASE: Finished copying Database dictionary.db from the assets folder, to  /data/data/m.example.so55711282dictionary/databases/dictionary.db12288were copied, in 3 blocks of size 4096.
04-17 19:24:54.251 3233-3233/m.example.so55711282dictionary D/COPYDATABASE: All Streams have been flushed and closed.
04-17 19:24:54.273 3233-3233/m.example.so55711282dictionary I/System.out: >>>>> Dumping cursor android.database.sqlite.SQLiteCursor@22ee92e7
04-17 19:24:54.273 3233-3233/m.example.so55711282dictionary I/System.out: 0 {
04-17 19:24:54.273 3233-3233/m.example.so55711282dictionary I/System.out:    id=1
04-17 19:24:54.273 3233-3233/m.example.so55711282dictionary I/System.out:    word=Apple
04-17 19:24:54.273 3233-3233/m.example.so55711282dictionary I/System.out:    definition=Thing that drops from an Apple Tree.
04-17 19:24:54.273 3233-3233/m.example.so55711282dictionary I/System.out: }
04-17 19:24:54.273 3233-3233/m.example.so55711282dictionary I/System.out: 1 {
04-17 19:24:54.273 3233-3233/m.example.so55711282dictionary I/System.out:    id=2
04-17 19:24:54.273 3233-3233/m.example.so55711282dictionary I/System.out:    word=Bucket
04-17 19:24:54.273 3233-3233/m.example.so55711282dictionary I/System.out:    definition=Hand held container with carrying hanlde.
04-17 19:24:54.273 3233-3233/m.example.so55711282dictionary I/System.out: }
04-17 19:24:54.273 3233-3233/m.example.so55711282dictionary I/System.out: <<<<<

即数据库已从 Assets 文件夹复制，预期的行已转储。

运行 2

在不做任何更改的情况下重新运行应用程序(以测试它不会重新复制数据库):-这次 logcat 包含:-

04-17 19:30:57.444 3343-3343/? D/DBVERSION: The Database Version (as hard coded) is 1
04-17 19:30:57.445 3343-3343/? D/DBVERSION: The Database Version (as per the database file) is 1
04-17 19:30:57.445 3343-3343/? D/DBPATH: DB Path is /data/data/m.example.so55711282dictionary/databases/dictionary.db
04-17 19:30:57.449 3343-3343/? I/System.out: >>>>> Dumping cursor android.database.sqlite.SQLiteCursor@22ee92e7
04-17 19:30:57.449 3343-3343/? I/System.out: 0 {
04-17 19:30:57.449 3343-3343/? I/System.out:    id=1
04-17 19:30:57.449 3343-3343/? I/System.out:    word=Apple
04-17 19:30:57.450 3343-3343/? I/System.out:    definition=Thing that drops from an Apple Tree.
04-17 19:30:57.450 3343-3343/? I/System.out: }
04-17 19:30:57.450 3343-3343/? I/System.out: 1 {
04-17 19:30:57.450 3343-3343/? I/System.out:    id=2
04-17 19:30:57.450 3343-3343/? I/System.out:    word=Bucket
04-17 19:30:57.450 3343-3343/? I/System.out:    definition=Hand held container with carrying hanlde.
04-17 19:30:57.450 3343-3343/? I/System.out: }
04-17 19:30:57.450 3343-3343/? I/System.out: <<<<<

即数据库，因为它存在，尚未被复制。

运行 3.

数据库已通过使用外部工具添加另外两行进行修改，然后复制到 Assets 文件夹中以替换旧的数据库文件，并且 DB_VERSION 更改为 2。

日志包含:-

04-17 19:35:16.661 3459-3459/m.example.so55711282dictionary D/DBVERSION: The Database Version (as hard coded) is 2
04-17 19:35:16.661 3459-3459/m.example.so55711282dictionary D/DBVERSION: The Database Version (as per the database file) is 1
04-17 19:35:16.661 3459-3459/m.example.so55711282dictionary D/DBPATH: DB Path is /data/data/m.example.so55711282dictionary/databases/dictionary.db
04-17 19:35:16.661 3459-3459/m.example.so55711282dictionary D/DBPATH: DB Path is /data/data/m.example.so55711282dictionary/databases/dictionary.db
04-17 19:35:16.661 3459-3459/m.example.so55711282dictionary D/COPYDATABASE: Initiated Copy of the database file dictionary.db from the assets folder.
04-17 19:35:16.661 3459-3459/m.example.so55711282dictionary D/COPYDATABASE: Asset file dictionary.db found so attmepting to copy to /data/data/m.example.so55711282dictionary/databases/dictionary.db
04-17 19:35:16.662 3459-3459/m.example.so55711282dictionary D/COPYDATABASE: Attempting copy of block 1 which has 4096 bytes.
04-17 19:35:16.662 3459-3459/m.example.so55711282dictionary D/COPYDATABASE: Attempting copy of block 2 which has 4096 bytes.
04-17 19:35:16.662 3459-3459/m.example.so55711282dictionary D/COPYDATABASE: Attempting copy of block 3 which has 4096 bytes.
04-17 19:35:16.662 3459-3459/m.example.so55711282dictionary D/COPYDATABASE: Finished copying Database dictionary.db from the assets folder, to  /data/data/m.example.so55711282dictionary/databases/dictionary.db12288were copied, in 3 blocks of size 4096.
04-17 19:35:16.662 3459-3459/m.example.so55711282dictionary D/COPYDATABASE: All Streams have been flushed and closed.
04-17 19:35:16.689 3459-3459/m.example.so55711282dictionary I/System.out: >>>>> Dumping cursor android.database.sqlite.SQLiteCursor@16011e94
04-17 19:35:16.689 3459-3459/m.example.so55711282dictionary I/System.out: 0 {
04-17 19:35:16.689 3459-3459/m.example.so55711282dictionary I/System.out:    id=1
04-17 19:35:16.689 3459-3459/m.example.so55711282dictionary I/System.out:    word=Apple
04-17 19:35:16.689 3459-3459/m.example.so55711282dictionary I/System.out:    definition=Thing that drops from an Apple Tree.
04-17 19:35:16.689 3459-3459/m.example.so55711282dictionary I/System.out: }
04-17 19:35:16.689 3459-3459/m.example.so55711282dictionary I/System.out: 1 {
04-17 19:35:16.689 3459-3459/m.example.so55711282dictionary I/System.out:    id=2
04-17 19:35:16.689 3459-3459/m.example.so55711282dictionary I/System.out:    word=Bucket
04-17 19:35:16.689 3459-3459/m.example.so55711282dictionary I/System.out:    definition=Hand held container with carrying hanlde.
04-17 19:35:16.689 3459-3459/m.example.so55711282dictionary I/System.out: }
04-17 19:35:16.689 3459-3459/m.example.so55711282dictionary I/System.out: 2 {
04-17 19:35:16.690 3459-3459/m.example.so55711282dictionary I/System.out:    id=3
04-17 19:35:16.690 3459-3459/m.example.so55711282dictionary I/System.out:    word=Yelllow
04-17 19:35:16.690 3459-3459/m.example.so55711282dictionary I/System.out:    definition=A colour.
04-17 19:35:16.690 3459-3459/m.example.so55711282dictionary I/System.out: }
04-17 19:35:16.690 3459-3459/m.example.so55711282dictionary I/System.out: 3 {
04-17 19:35:16.690 3459-3459/m.example.so55711282dictionary I/System.out:    id=4
04-17 19:35:16.690 3459-3459/m.example.so55711282dictionary I/System.out:    word=Zebra
04-17 19:35:16.690 3459-3459/m.example.so55711282dictionary I/System.out:    definition=A balck and white, horse-like animal.
04-17 19:35:16.690 3459-3459/m.example.so55711282dictionary I/System.out: }
04-17 19:35:16.690 3459-3459/m.example.so55711282dictionary I/System.out: <<<<<

运行 4.

应用重新运行(不重新复制数据库并转储 4 行)

运行 5.

应用程序被卸载并重新运行(反射(reflect)当数据库版本为 2 时应用程序的新安装(例如，从 playstore 新下载/安装应用程序)):-

复制数据库(4 行版本)并转储 4 行。

• 请注意，数据库版本(根据数据库文件)是 -666666666 消息已包含在内。这在没有要替换的数据库时显示(可以很容易地更改数字以适应)。