【问题标题】：Overwrite existing shipped Sqlite DB with the new DB version on my next Android App Update在我的下一个 Android 应用程序更新中，用新的数据库版本覆盖现有的 Sqlite 数据库
【发布时间】：2019-07-03 15:01:31
【问题描述】：

我想在我的下一次应用更新中用新的完全填充的数据库覆盖我的旧应用版本附带的现有数据库。但是，onUpgrade() 永远不会被调用，尽管我尝试在将 DB_version 传递给 SQLiteOpenHelper 类时更改它。

public class DataBaseHelper extends SQLiteOpenHelper {

    private static Context mContext;
    private static String DB_PATH = "/data/data/<app Package>/databases/";;
    private static final String DBNAME = "DB.db";
    private static DataBaseHelper sInstance;
    private static final int version = 2;


    public static synchronized DataBaseHelper getInstance(Context context) {
        // Use the application context, which will ensure that you
        // don't accidentally leak an Activity's context.
        if (sInstance == null) {
            sInstance = new DataBaseHelper(context.getApplicationContext());
        }
        return sInstance;
    }

    public DataBaseHelper(Context context, String s){
        super(context, DBNAME, null, version);

    }

    private DataBaseHelper(Context context) {
        super(context, DBNAME, null, version);
        mContext = context;

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR1) {
            DB_PATH = context.getApplicationInfo().dataDir + "/databases/";
        } else {
            DB_PATH = "/data/data/" + context.getPackageName() + "/databases/";
        }

        new Handler().post(new Runnable() {

            @Override
            public void run() {
                // If u want to Copy Database from Assets.
                try {
                    CopyAndCreateDataBase();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        });
    }


    // If database not exists copy it from the assets
    public void CopyAndCreateDataBase() throws IOException {
        boolean mDataBaseExist = checkDataBase();
        if (!mDataBaseExist) {
            this.getReadableDatabase();
            this.getWritableDatabase();
            this.close();
            try {
                // Copy the database from assests
                copyDataBase();
                String mPath = DB_PATH + DBNAME;
            } catch (IOException mIOException) {
                throw new Error("ErrorCopyingDataBase");
            }
        }
         //FOR DB TESTING PURPOSES
        else{
            Log.d("DB STATUS:", "Database Already Exists!!!!!!!!!");
        }
    }


    // Check that the database exists here: /data/data/yourpackage/databases/DatabaseName
    private boolean checkDataBase() {
        File dbFile = new File(DB_PATH + DBNAME);
        // Log.v("dbFile", dbFile + "   "+ dbFile.exists());
        return dbFile.exists();
    }

    // Copy the database from assets
    private void copyDataBase() throws IOException {
        InputStream mInput = mContext.getAssets().open(DBNAME);
        String outFileName = DB_PATH + DBNAME;
        OutputStream mOutput = new FileOutputStream(outFileName);
        byte[] mBuffer = new byte[1024];
        int mLength;
        while ((mLength = mInput.read(mBuffer)) > 0) {
            mOutput.write(mBuffer, 0, mLength);
        }
        Log.d("DB STATUS:", "Daatabase Created ----------------"); //FOR DB TESTING PURPOSES
        mOutput.flush();
        mOutput.close();
        mInput.close();
    }

    @Override
    public void onCreate(SQLiteDatabase sqLiteDatabase) {

    }

    @Override
    public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {
        Log.d("Database Versions:", "old:"+i+"\nnew:"+i1);

    }
}

我尝试了很多方法来触发 onUpgrade() 方法，例如调用 getReadableDatabase() 和 getWritableDatabase(，但不幸的是它确实成功了。我想用新发布的数据库覆盖现有的数据库。

【问题讨论】：

尝试增加版本整数？

标签： android database sqlite version

【解决方案1】：

我认为您的问题（初始问题，请阅读完整答案）可能正在使用处理程序。当然，测试可用代码会导致意想不到的结果（数据库始终报告为存在，因此永远不要从资产中复制数据库，如果数据库存在则永远不会调用 onUpgrade（我的猜测是数据库已经打开由于隐式打开，因此没有尝试进行打开处理））。

改用：-

    try {
        CopyAndCreateDataBase();
    } catch (IOException e) {
        e.printStackTrace();
    }

    /*
    new Handler().post(new Runnable() {

        @Override
        public void run() {
            // If u want to Copy Database from Assets.
            try {
                CopyAndCreateDataBase();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    });
    */

产生预期的结果，例如:-

07-04 06:55:38.836 4365-4365/aso.so56873021recopydb D/DBEXISTS: The database /data/user/0/aso.so56873021recopydb/databases/DB.db was found.
07-04 06:55:38.836 4365-4365/aso.so56873021recopydb D/DB STATUS:: Database Already Exists!!!!!!!!!
07-04 06:55:38.838 4365-4365/aso.so56873021recopydb D/Database Versions:: old:1
    new:2

请注意，在测试代码以确定问题时添加了 DBEXISTS 消息。

测试在活动中使用了以下代码：-

public class MainActivity extends AppCompatActivity {


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        DataBaseHelper mDBHlpr = DataBaseHelper.getInstance(this);
        Cursor csr = mDBHlpr.getWritableDatabase().query("sqlite_master",null,null,null,null,null,null);
        DatabaseUtils.dumpCursor(csr);
    }
}

第 2 部分 - 升级

简而言之，即使您可以调用 onUpgrade 在修复上一个问题后增加版本，因为当调用 onUpgrade 时数据库已经打开并复制新数据库将有效地撤消，因为旧数据库将覆盖新复制的数据库，因此更改会丢失。

相反，我建议在实例化数据库助手之前检查、复制和覆盖数据库，例如在 getInstance 方法中。

因此，我建议使用以下数据库助手（请参阅 cmets 了解所做的更改）：-

public class DataBaseHelper extends SQLiteOpenHelper {

    private static Context mContext;
    //private static String DB_PATH = "/data/data/<app Package>/databases/"; //NOT NEEDED Contexts getDatabasePath used instead
    private static final String DBNAME = "DB.db";
    private static DataBaseHelper sInstance;
    private static final int version = 2;


    public static synchronized DataBaseHelper getInstance(Context context) {
        // Use the application context, which will ensure that you
        // don't accidentally leak an Activity's context.
        checkDB(context.getApplicationContext(),DBNAME,version); //<<<<<<<<<< do the stuff before DatabaseHelper instantiation
        if (sInstance == null) {
            sInstance = new DataBaseHelper(context.getApplicationContext());
        }
        return sInstance;
    }

    private DataBaseHelper(Context context) {
        super(context, DBNAME, null, version);
        mContext = context;
    }

    // Copy the database from assets
    //<<<<<<<<<< CHANGED TO USE getDatabasepath requiring Context to be passed
    private static void copyDataBase(Context context) throws IOException {
        InputStream mInput = context.getAssets().open(DBNAME);
        String outFileName = context.getDatabasePath(DBNAME).toString();
        OutputStream mOutput = new FileOutputStream(outFileName);
        Log.d("DBCOPY","DB Copy inititaed"); //<<<<<<<<<< ADDED FOR TESTING
        byte[] mBuffer = new byte[1024];
        int mLength;
        int bytescopied = 0;
        while ((mLength = mInput.read(mBuffer)) > 0) {
            mOutput.write(mBuffer, 0, mLength);
            bytescopied = bytescopied + mLength;
        }
        Log.d("DBCOPY", "Database copied. " + String.valueOf(bytescopied) + " bytes copied." ); //<<<<<<<<<< ADDED FOR TESTING
        Log.d("DB STATUS:", "Daatabase Created ----------------"); //FOR DB TESTING PURPOSES
        mOutput.flush();
        mOutput.close();
        mInput.close();
    }

    @Override
    public void onCreate(SQLiteDatabase sqLiteDatabase) {

    }

    @Override
    public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {
        //<<<<<<<<<< ONLY USE ME FOR SCHEMA CHANGES !!!!NOT!!!! new DB copy
        Log.d("Database Versions:", "old:"+i+"\nnew:"+i1);
    }

    //<<<<<<<<<< NEW 
    private static void checkDB(Context context, String dbname, int version) {
        int dbversion;
        // Note uses the Contexts getDatabasePath
        File dbfile = new File(context.getDatabasePath(dbname).toString());
        if (!dbfile.exists()) {
            //<<<<<<<<<< create the databases directory (or whatever it is the future)
            if (!dbfile.getParentFile().exists()) {
                dbfile.getParentFile().mkdirs();
            }
            //<<<<<<<<<< Now do the copy of the initial DB 
            //<<<<<<<<<< Note new install will copy the latest DB
            try {
                copyDataBase(context);
            } catch (IOException e) {
                e.printStackTrace();
                throw new Error("Error copying initial Database.");
            }
        } 

        // If the database file does exist then retrieve the version
        else {


            SQLiteDatabase db = SQLiteDatabase.openDatabase(context.getDatabasePath(dbname).toString(),null,SQLiteDatabase.OPEN_READWRITE);
            dbversion = db.getVersion();
            Log.d("DBVERSION","The stored database version is " + String.valueOf(dbversion));
            db.close();

            //<<<<<<<<<< if the database's version is less than the coded version then copy the DB
            //<<<<<<<<<< NOTE!!!! always assumes new version = new copy
            //<<<<<<<<<< IF NOt WANTED THEN DO SPECIFIC VERSION CHECKING 
            if (dbversion <  version) {

                //<<<<<<<<<<<< EXAMPLE skip copy on version 10 >>>>>>>>>>
                //<TODO> Remove example check if not needed
                if (dbversion < version && version == 10) {
                    return;
                }
                //<<<<<<<<<< For Android 9+ delete the -wal and -shm files if copying database
                if (new File(context.getDatabasePath(dbname).toString() + "-wal").exists()) {
                    new File(context.getDatabasePath(dbname).toString() + "-wal").delete();
                }
                if (new File(context.getDatabasePath(dbname).toString() + "-shm").exists()) {
                    new File(context.getDatabasePath(dbname).toString() + "-shm").delete();
                }
                try {
                    copyDataBase(context);
                } catch (IOException e) {
                    e.printStackTrace();
                    throw new Error("Error copying upgraded database");
                }
            }
        }
    }
}

测试

以上内容已经过测试。测试基于两个数据库（完全不同），在活动中使用以下内容：-

public class MainActivity extends AppCompatActivity {


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        DataBaseHelper mDBHlpr = DataBaseHelper.getInstance(this);
        Cursor csr = mDBHlpr.getWritableDatabase().query("sqlite_master",null,null,null,null,null,null);
        DatabaseUtils.dumpCursor(csr);
    }
}

以下是资产文件夹：-

被 OLDDB.db 复制到 DB.db 的原始数据库。 NEWDB.db 将是后续的新数据库。

在两个设备 API 23 和 API 28（Oreo so Pie+ 和 WAL）上进行了测试。

第一阶段

首先使用上述文件运行应用程序，并将版本设置为 1。导致日志包含：-

07-04 10:20:32.120 8154-8154/aso.so56873021recopydb D/DBCOPY: DB Copy inititaed
07-04 10:20:32.120 8154-8154/aso.so56873021recopydb D/DBCOPY: Database copied. 36864 bytes copied.
07-04 10:20:32.120 8154-8154/aso.so56873021recopydb D/DB STATUS:: Daatabase Created ----------------
07-04 10:20:32.140 8154-8154/aso.so56873021recopydb I/System.out: >>>>> Dumping cursor android.database.sqlite.SQLiteCursor@6e2c433
07-04 10:20:32.140 8154-8154/aso.so56873021recopydb I/System.out: 0 {
07-04 10:20:32.140 8154-8154/aso.so56873021recopydb I/System.out:    type=table
07-04 10:20:32.140 8154-8154/aso.so56873021recopydb I/System.out:    name=android_metadata
07-04 10:20:32.140 8154-8154/aso.so56873021recopydb I/System.out:    tbl_name=android_metadata
07-04 10:20:32.140 8154-8154/aso.so56873021recopydb I/System.out:    rootpage=3
07-04 10:20:32.140 8154-8154/aso.so56873021recopydb I/System.out:    sql=CREATE TABLE android_metadata (locale TEXT)
07-04 10:20:32.140 8154-8154/aso.so56873021recopydb I/System.out: }
07-04 10:20:32.140 8154-8154/aso.so56873021recopydb I/System.out: 1 {
07-04 10:20:32.140 8154-8154/aso.so56873021recopydb I/System.out:    type=table
07-04 10:20:32.140 8154-8154/aso.so56873021recopydb I/System.out:    name=room_master_table
07-04 10:20:32.140 8154-8154/aso.so56873021recopydb I/System.out:    tbl_name=room_master_table
07-04 10:20:32.140 8154-8154/aso.so56873021recopydb I/System.out:    rootpage=4
07-04 10:20:32.140 8154-8154/aso.so56873021recopydb I/System.out:    sql=CREATE TABLE room_master_table (id INTEGER PRIMARY KEY,identity_hash TEXT)
07-04 10:20:32.140 8154-8154/aso.so56873021recopydb I/System.out: }
..........

36K 复制
笔记表room_master_table

API 28 设备上的类似结果：-

2019-07-04 10:22:33.082 4532-4532/aso.so56873021recopydb D/DBCOPY: DB Copy inititaed
2019-07-04 10:22:33.083 4532-4532/aso.so56873021recopydb D/DBCOPY: Database copied. 36864 bytes copied.
2019-07-04 10:22:33.083 4532-4532/aso.so56873021recopydb D/DB STATUS:: Daatabase Created ----------------
2019-07-04 10:22:33.088 4532-4532/aso.so56873021recopydb I/System.out: >>>>> Dumping cursor android.database.sqlite.SQLiteCursor@2f7f7bc
2019-07-04 10:22:33.089 4532-4532/aso.so56873021recopydb I/System.out: 0 {

第二阶段

应用程序再次运行，没有更改结果（即没有数据库副本）：-

07-04 10:24:13.642 8244-8244/? D/DBVERSION: The stored database version is 1
07-04 10:24:13.644 8244-8244/? I/System.out: >>>>> Dumping cursor android.database.sqlite.SQLiteCursor@8c743f0

在 API 28 设备上：-

2019-07-04 10:26:24.531 4620-4620/? D/DBVERSION: The stored database version is 1
2019-07-04 10:26:24.536 4620-4620/? I/System.out: >>>>> Dumping cursor android.database.sqlite.SQLiteCursor@877f345

第三阶段

资产文件夹中的文件更改为：-

应用重新运行无需更改版本：-

没有复制和原始数据：-

07-04 10:30:01.838 8369-8369/? D/DBVERSION: The stored database version is 1
07-04 10:30:01.840 8369-8369/? I/System.out: >>>>> Dumping cursor android.database.sqlite.SQLiteCursor@8c743f0
07-04 10:30:01.840 8369-8369/? I/System.out: 0 {
07-04 10:30:01.840 8369-8369/? I/System.out:    type=table
07-04 10:30:01.840 8369-8369/? I/System.out:    name=android_metadata
07-04 10:30:01.840 8369-8369/? I/System.out:    tbl_name=android_metadata
07-04 10:30:01.840 8369-8369/? I/System.out:    rootpage=3
07-04 10:30:01.840 8369-8369/? I/System.out:    sql=CREATE TABLE android_metadata (locale TEXT)
07-04 10:30:01.840 8369-8369/? I/System.out: }
07-04 10:30:01.840 8369-8369/? I/System.out: 1 {
07-04 10:30:01.840 8369-8369/? I/System.out:    type=table
07-04 10:30:01.840 8369-8369/? I/System.out:    name=room_master_table

在 API 28 上：-

2019-07-04 10:31:11.591 4757-4757/aso.so56873021recopydb D/DBVERSION: The stored database version is 1
2019-07-04 10:31:11.596 4757-4757/aso.so56873021recopydb I/System.out: >>>>> Dumping cursor android.database.sqlite.SQLiteCursor@877f345
2019-07-04 10:31:11.596 4757-4757/aso.so56873021recopydb I/System.out: 0 {
2019-07-04 10:31:11.596 4757-4757/aso.so56873021recopydb I/System.out:    type=table
2019-07-04 10:31:11.596 4757-4757/aso.so56873021recopydb I/System.out:    name=android_metadata
2019-07-04 10:31:11.596 4757-4757/aso.so56873021recopydb I/System.out:    tbl_name=android_metadata
2019-07-04 10:31:11.597 4757-4757/aso.so56873021recopydb I/System.out:    rootpage=3
2019-07-04 10:31:11.597 4757-4757/aso.so56873021recopydb I/System.out:    sql=CREATE TABLE android_metadata (locale TEXT)
2019-07-04 10:31:11.597 4757-4757/aso.so56873021recopydb I/System.out: }
2019-07-04 10:31:11.597 4757-4757/aso.so56873021recopydb I/System.out: 1 {
2019-07-04 10:31:11.597 4757-4757/aso.so56873021recopydb I/System.out:    type=table
2019-07-04 10:31:11.597 4757-4757/aso.so56873021recopydb I/System.out:    name=room_master_table

第 4 阶段

version increased from 1 to 2 :-

07-04 10:38:42.679 8857-8857/? D/DBVERSION: The stored database version is 1
07-04 10:38:42.679 8857-8857/? D/DBCOPY: DB Copy inititaed
07-04 10:38:42.680 8857-8857/? D/DBCOPY: Database copied. 77824 bytes copied.
07-04 10:38:42.680 8857-8857/? D/DB STATUS:: Daatabase Created ----------------
07-04 10:38:42.683 8857-8857/? D/Database Versions:: old:1
    new:2
07-04 10:38:42.688 8857-8857/? I/System.out: >>>>> Dumping cursor android.database.sqlite.SQLiteCursor@f2b3d69
07-04 10:38:42.688 8857-8857/? I/System.out: 0 {
07-04 10:38:42.688 8857-8857/? I/System.out:    type=table
07-04 10:38:42.688 8857-8857/? I/System.out:    name=android_metadata
07-04 10:38:42.688 8857-8857/? I/System.out:    tbl_name=android_metadata
07-04 10:38:42.688 8857-8857/? I/System.out:    rootpage=3
07-04 10:38:42.689 8857-8857/? I/System.out:    sql=CREATE TABLE android_metadata (locale TEXT)
07-04 10:38:42.689 8857-8857/? I/System.out: }
07-04 10:38:42.689 8857-8857/? I/System.out: 1 {
07-04 10:38:42.689 8857-8857/? I/System.out:    type=table
07-04 10:38:42.689 8857-8857/? I/System.out:    name=shops
07-04 10:38:42.689 8857-8857/? I/System.out:    tbl_name=shops
07-04 10:38:42.689 8857-8857/? I/System.out:    rootpage=4
07-04 10:38:42.689 8857-8857/? I/System.out:    sql=CREATE TABLE shops (_id INTEGER  PRIMARY KEY , shoporder INTEGER  DEFAULT 1000 , shopname TEXT , shopstreet TEXT , shopcity TEXT , shopstate TEXT , shopnotes TEXT )
07-04 10:38:42.689 8857-8857/? I/System.out: }
........

注意 76K 已复制，表现在是商店

在 API 28 上：-

2019-07-04 10:40:31.799 5010-5010/aso.so56873021recopydb D/DBVERSION: The stored database version is 1
2019-07-04 10:40:31.800 5010-5010/aso.so56873021recopydb D/DBCOPY: DB Copy inititaed
2019-07-04 10:40:31.802 5010-5010/aso.so56873021recopydb D/DBCOPY: Database copied. 77824 bytes copied.
2019-07-04 10:40:31.802 5010-5010/aso.so56873021recopydb D/DB STATUS:: Daatabase Created ----------------
2019-07-04 10:40:31.826 5010-5010/aso.so56873021recopydb D/Database Versions:: old:1
    new:2
...........

第五阶段

应用程序再次运行（即已完成后复制）：-

07-04 10:41:53.653 8947-8947/? D/DBVERSION: The stored database version is 2
07-04 10:41:53.655 8947-8947/? I/System.out: >>>>> Dumping cursor android.database.sqlite.SQLiteCursor@8c743f0
07-04 10:41:53.655 8947-8947/? I/System.out: 0 {
07-04 10:41:53.655 8947-8947/? I/System.out:    type=table
07-04 10:41:53.655 8947-8947/? I/System.out:    name=android_metadata
07-04 10:41:53.655 8947-8947/? I/System.out:    tbl_name=android_metadata
07-04 10:41:53.655 8947-8947/? I/System.out:    rootpage=3
07-04 10:41:53.655 8947-8947/? I/System.out:    sql=CREATE TABLE android_metadata (locale TEXT)
07-04 10:41:53.655 8947-8947/? I/System.out: }
07-04 10:41:53.655 8947-8947/? I/System.out: 1 {
07-04 10:41:53.655 8947-8947/? I/System.out:    type=table
07-04 10:41:53.655 8947-8947/? I/System.out:    name=shops
07-04 10:41:53.655 8947-8947/? I/System.out:    tbl_name=shops

在 API 28 上：-

2019-07-04 10:42:41.296 5098-5098/aso.so56873021recopydb D/DBVERSION: The stored database version is 2
2019-07-04 10:42:41.306 5098-5098/aso.so56873021recopydb I/System.out: >>>>> Dumping cursor android.database.sqlite.SQLiteCursor@877f345
2019-07-04 10:42:41.307 5098-5098/aso.so56873021recopydb I/System.out: 0 {
2019-07-04 10:42:41.308 5098-5098/aso.so56873021recopydb I/System.out:    type=table
2019-07-04 10:42:41.308 5098-5098/aso.so56873021recopydb I/System.out:    name=android_metadata
2019-07-04 10:42:41.308 5098-5098/aso.so56873021recopydb I/System.out:    tbl_name=android_metadata
2019-07-04 10:42:41.308 5098-5098/aso.so56873021recopydb I/System.out:    rootpage=3
2019-07-04 10:42:41.308 5098-5098/aso.so56873021recopydb I/System.out:    sql=CREATE TABLE android_metadata (locale TEXT)
2019-07-04 10:42:41.308 5098-5098/aso.so56873021recopydb I/System.out: }
2019-07-04 10:42:41.308 5098-5098/aso.so56873021recopydb I/System.out: 1 {
2019-07-04 10:42:41.308 5098-5098/aso.so56873021recopydb I/System.out:    type=table
2019-07-04 10:42:41.308 5098-5098/aso.so56873021recopydb I/System.out:    name=shops
2019-07-04 10:42:41.309 5098-5098/aso.so56873021recopydb I/System.out:    tbl_name=shops

【讨论】：

非常感谢您的及时和非常详细的回答...我会检查并回复您
感谢上帝......你应该得到一颗星......非常感谢你的帮助:)