【问题标题】：Having trouble copying an existing sqlite db file from assets to android project将现有的 sqlite db 文件从资产复制到 android 项目时遇到问题
【发布时间】：2019-02-21 08:15:19
【问题描述】：

我有以下代码：

private void copyDataBase() throws IOException {
    Context context = this.getApplicationContext();

    // Open your local db as the input stream
    InputStream myInput = context.getAssets().open(DB_NAME);

    // Define output file name
    File outfile = new File(context.getDatabasePath(DB_NAME).toString());
    outfile.setWritable(true);

    // Open the empty db as the output stream
    OutputStream myOutput = new FileOutputStream(outfile);

    // 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();
}

但是，它在 OutputStream 变量上一直失败。不断抛出的错误是：

java.io.FileNotFoundException ... mydb.db: open failed: ENOTDIR (Not a directory)

我的 SQLite 文件在项目的 assets 目录中，我的 minSdkVersion 是 19 和 targetSdkVersion 是 28。

这是来自下面 cmets 的函数调用的更新版本，它仍然失败。

private void copyDataBase() throws IOException {
    Context context = this.getApplicationContext();

    // Open your local db as the input stream
    InputStream myInput = context.getAssets().open(DB_NAME);

    // Define output file name
    File outfile = new File(context.getDatabasePath(DB_NAME).toString());

    try {
        // Define path to database file and make directories if necessary
        File dir = new File(DB_PATH);
        if (!dir.exists()) {
            boolean madeDirectory = dir.mkdirs();
            Log.d(TAG, String.format("copyDataBase: Made directories: %s", madeDirectory));
        }

        if (!outfile.exists()){
            outfile.createNewFile();
        }
    } catch (Exception e) {
        e.printStackTrace();
    }

    // Open the empty db as the output stream
    OutputStream myOutput = new FileOutputStream(outfile);

    // 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();
}

变量DB_NAME只是我正在使用的数据库文件的名称myExample.db

getDatabasePath 函数调用生成的字符串是"/data/data/projectname/databases/myExample.db

【问题讨论】：

标签： java android sqlite copy assets

【解决方案1】：

我相信您的问题是数据库文件夹不存在。而只是 /data/data/<the_package>/ 存在。

所以尝试根据 cmets 添加代码：-

File outfile = new File(context.getDatabasePath(DB_NAME).toString()); //<<<<<<<<< EXISTING LINE
if (!outfile.getParentFile().exists()) { //<<<<<<<<<< ADDED
    outfile.getParentFile().mkdirs(); //<<<<<<<<<< ADDED
} //<<<<<<<<<< ADDED

我倾向于在检查数据库是否存在时创建目录，例如:-

private boolean checkDataBase() {
    /**
     * Does not open the database instead checks to see if the file exists
     * also creates the databases directory if it does not exist
     * (the real reason why the database is opened, which appears to result in issues)
     */

    File db = new File(myContext.getDatabasePath(DB_NAME).getPath()); //Get the file name of the database
    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 exist then make the directory (and higher level directories if need be)
    if (!dbdir.exists()) {
        dbdir.mkdirs();
    }
    return false;
}

复制问题

使用代码：-

private void copyDataBase() throws IOException {

        final String TAG = "COPYDATABASE";

        //Open your local db as the input stream
        Log.d(TAG,"Initiated Copy of the database file " + DB_NAME + " from the assets folder.");
        InputStream myInput = myContext.getAssets().open(DB_NAME); // Open the Asset file
        String dbpath = myContext.getDatabasePath(DB_NAME).getPath();
        Log.d(TAG,"Asset file " + DB_NAME + " found so attmepting to copy to " + dbpath);

        // Path to the just created empty db
        //String outFileName = DB_PATH + DB_NAME;
        //Open the empty db as the output stream
        File outfile = new File(myContext.getDatabasePath(DB_NAME).toString());
        Log.d("DBPATH","path is " + outfile.getPath());
        outfile.setWritable(true);
        //OutputStream myoutputx2 = new FileOutputStream(outfile);
        if (!outfile.getParentFile().exists()) {
            outfile.getParentFile().mkdirs();
        }

        OutputStream myOutput = new FileOutputStream(outfile);
        //transfer bytes from the inputfile to the outputfile
        byte[] buffer = new byte[buffer_size];
        int length;
        while ((length = myInput.read(buffer))>0) {
            blocks_copied++;
            Log.d(TAG,"Ateempting copy of block " + String.valueOf(blocks_copied) + " which has " + String.valueOf(length) + " bytes.");
            myOutput.write(buffer, 0, length);
            bytes_copied += length;
        }
        Log.d(TAG,
                "Finished copying Database " + DB_NAME +
                        " from the assets folder, to  " + dbpath +
                        String.valueOf(bytes_copied) + "were copied, in " +
                        String.valueOf(blocks_copied) + " blocks of size " +
                        String.valueOf(buffer_size) + "."
        );
        //Close the streams
        myOutput.flush();
        myOutput.close();
        myInput.close();
        Log.d(TAG,"All Streams have been flushed and closed.");
    }

导致您收到的错误：-

02-21 10:17:25.975 7604-7604/so.cdfa D/VERSION: Build Version is 22
02-21 10:17:25.975 7604-7604/so.cdfa D/DBPATH: DB Path is /data/data/so.cdfa/databases/db
02-21 10:17:25.975 7604-7604/so.cdfa D/DBPATH: DB Path is /data/data/so.cdfa/databases/db
02-21 10:17:25.976 7604-7604/so.cdfa D/COPYDATABASE: Initiated Copy of the database file db from the assets folder.
02-21 10:17:25.976 7604-7604/so.cdfa D/COPYDATABASE: Asset file db found so attmepting to copy to /data/data/so.cdfa/databases/db
02-21 10:17:25.976 7604-7604/so.cdfa D/DBPATH: path is /data/data/so.cdfa/databases/db
02-21 10:17:25.976 7604-7604/so.cdfa W/System.err: java.io.FileNotFoundException: /data/data/so.cdfa/databases/db: open failed: ENOENT (No such file or directory)
02-21 10:17:25.976 7604-7604/so.cdfa W/System.err:     at libcore.io.IoBridge.open(IoBridge.java:456)
02-21 10:17:25.976 7604-7604/so.cdfa W/System.err:     at java.io.FileOutputStream.<init>(FileOutputStream.java:87)
02-21 10:17:25.976 7604-7604/so.cdfa W/System.err:     at java.io.FileOutputStream.<init>(FileOutputStream.java:72)
02-21 10:17:25.976 7604-7604/so.cdfa W/System.err:     at so.cdfa.DBHelper.copyDataBase(DBHelper.java:120)
02-21 10:17:25.976 7604-7604/so.cdfa W/System.err:     at so.cdfa.DBHelper.createDataBase(DBHelper.java:58)
02-21 10:17:25.976 7604-7604/so.cdfa W/System.err:     at so.cdfa.DBHelper.<init>(DBHelper.java:32)
02-21 10:17:25.976 7604-7604/so.cdfa W/System.err:     at so.cdfa.MainActivity.onCreate(MainActivity.java:60)
02-21 10:17:25.976 7604-7604/so.cdfa W/System.err:     at android.app.Activity.performCreate(Activity.java:5990)
02-21 10:17:25.976 7604-7604/so.cdfa W/System.err:     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106)
02-21 10:17:25.976 7604-7604/so.cdfa W/System.err:     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2278)
02-21 10:17:25.976 7604-7604/so.cdfa W/System.err:     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387)
02-21 10:17:25.976 7604-7604/so.cdfa W/System.err:     at android.app.ActivityThread.access$800(ActivityThread.java:151)
02-21 10:17:25.977 7604-7604/so.cdfa W/System.err:     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303)
02-21 10:17:25.977 7604-7604/so.cdfa W/System.err:     at android.os.Handler.dispatchMessage(Handler.java:102)
02-21 10:17:25.977 7604-7604/so.cdfa W/System.err:     at android.os.Looper.loop(Looper.java:135)
02-21 10:17:25.977 7604-7604/so.cdfa W/System.err:     at android.app.ActivityThread.main(ActivityThread.java:5254)
02-21 10:17:25.977 7604-7604/so.cdfa W/System.err:     at java.lang.reflect.Method.invoke(Native Method)
02-21 10:17:25.977 7604-7604/so.cdfa W/System.err:     at java.lang.reflect.Method.invoke(Method.java:372)
02-21 10:17:25.977 7604-7604/so.cdfa W/System.err:     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
02-21 10:17:25.977 7604-7604/so.cdfa W/System.err:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
02-21 10:17:25.977 7604-7604/so.cdfa W/System.err: Caused by: android.system.ErrnoException: open failed: ENOENT (No such file or directory)
02-21 10:17:25.977 7604-7604/so.cdfa W/System.err:     at libcore.io.Posix.open(Native Method)
02-21 10:17:25.977 7604-7604/so.cdfa W/System.err:     at libcore.io.BlockGuardOs.open(BlockGuardOs.java:186)
02-21 10:17:25.977 7604-7604/so.cdfa W/System.err:     at libcore.io.IoBridge.open(IoBridge.java:442)
02-21 10:17:25.977 7604-7604/so.cdfa W/System.err:  ... 19 more
02-21 10:17:25.977 7604-7604/so.cdfa D/AndroidRuntime: Shutting down VM
02-21 10:17:25.977 7604-7604/so.cdfa E/AndroidRuntime: FATAL EXCEPTION: main
    Process: so.cdfa, PID: 7604
    java.lang.RuntimeException: Unable to start activity ComponentInfo{so.cdfa/so.cdfa.MainActivity}: java.lang.RuntimeException: Error copying database (see stack-trace above)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2325)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387)
        at android.app.ActivityThread.access$800(ActivityThread.java:151)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303)
        at android.os.Handler.dispatchMessage(Handler.java:102)
        at android.os.Looper.loop(Looper.java:135)
        at android.app.ActivityThread.main(ActivityThread.java:5254)
        at java.lang.reflect.Method.invoke(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:372)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
     Caused by: java.lang.RuntimeException: Error copying database (see stack-trace above)
        at so.cdfa.DBHelper.createDataBase(DBHelper.java:65)

将代码修改为（根据原始答案）：-

private void copyDataBase() throws IOException {

    final String TAG = "COPYDATABASE";

    //Open your local db as the input stream
    Log.d(TAG,"Initiated Copy of the database file " + DB_NAME + " from the assets folder.");
    InputStream myInput = myContext.getAssets().open(DB_NAME); // Open the Asset file
    String dbpath = myContext.getDatabasePath(DB_NAME).getPath();
    Log.d(TAG,"Asset file " + DB_NAME + " found so attmepting to copy to " + dbpath);

    // Path to the just created empty db
    //String outFileName = DB_PATH + DB_NAME;
    //Open the empty db as the output stream
    File outfile = new File(myContext.getDatabasePath(DB_NAME).toString());
    Log.d("DBPATH","path is " + outfile.getPath());
    outfile.setWritable(true); //<<<<<<<<<< not required as writable access exists
    //OutputStream myoutputx2 = new FileOutputStream(outfile);
    if (!outfile.getParentFile().exists()) {
        outfile.getParentFile().mkdirs();
    }

    OutputStream myOutput = new FileOutputStream(outfile);
    //transfer bytes from the inputfile to the outputfile
    byte[] buffer = new byte[buffer_size];
    int length;
    while ((length = myInput.read(buffer))>0) {
        blocks_copied++;
        Log.d(TAG,"Ateempting copy of block " + String.valueOf(blocks_copied) + " which has " + String.valueOf(length) + " bytes.");
        myOutput.write(buffer, 0, length);
        bytes_copied += length;
    }
    Log.d(TAG,
            "Finished copying Database " + DB_NAME +
                    " from the assets folder, to  " + dbpath +
                    String.valueOf(bytes_copied) + "were copied, in " +
                    String.valueOf(blocks_copied) + " blocks of size " +
                    String.valueOf(buffer_size) + "."
    );
    //Close the streams
    myOutput.flush();
    myOutput.close();
    myInput.close();
    Log.d(TAG,"All Streams have been flushed and closed.");
}

结果：-

02-21 10:24:31.808 7972-7972/? D/VERSION: Build Version is 22
02-21 10:24:31.808 7972-7972/? D/DBPATH: DB Path is /data/data/so.cdfa/databases/db
02-21 10:24:31.808 7972-7972/? D/DBPATH: DB Path is /data/data/so.cdfa/databases/db
02-21 10:24:31.808 7972-7972/? D/COPYDATABASE: Initiated Copy of the database file db from the assets folder.
02-21 10:24:31.808 7972-7972/? D/COPYDATABASE: Asset file db found so attmepting to copy to /data/data/so.cdfa/databases/db
02-21 10:24:31.808 7972-7972/? D/DBPATH: path is /data/data/so.cdfa/databases/db
02-21 10:24:31.809 7972-7972/? D/COPYDATABASE: Ateempting copy of block 1 which has 1024 bytes.
02-21 10:24:31.809 7972-7972/? D/COPYDATABASE: Ateempting copy of block 2 which has 1024 bytes.
02-21 10:24:31.809 7972-7972/? D/COPYDATABASE: Ateempting copy of block 3 which has 1024 bytes.
02-21 10:24:31.809 7972-7972/? D/COPYDATABASE: Ateempting copy of block 4 which has 1024 bytes.
02-21 10:24:31.809 7972-7972/? D/COPYDATABASE: Ateempting copy of block 5 which has 1024 bytes.
02-21 10:24:31.809 7972-7972/? D/COPYDATABASE: Ateempting copy of block 6 which has 1024 bytes.
02-21 10:24:31.809 7972-7972/? D/COPYDATABASE: Ateempting copy of block 7 which has 1024 bytes.
02-21 10:24:31.809 7972-7972/? D/COPYDATABASE: Ateempting copy of block 8 which has 1024 bytes.
02-21 10:24:31.809 7972-7972/? D/COPYDATABASE: Ateempting copy of block 9 which has 1024 bytes.
02-21 10:24:31.810 7972-7972/? D/COPYDATABASE: Ateempting copy of block 10 which has 1024 bytes.
02-21 10:24:31.810 7972-7972/? D/COPYDATABASE: Ateempting copy of block 11 which has 1024 bytes.
02-21 10:24:31.810 7972-7972/? D/COPYDATABASE: Ateempting copy of block 12 which has 1024 bytes.
02-21 10:24:31.810 7972-7972/? D/COPYDATABASE: Ateempting copy of block 13 which has 1024 bytes.
02-21 10:24:31.810 7972-7972/? D/COPYDATABASE: Ateempting copy of block 14 which has 1024 bytes.
02-21 10:24:31.810 7972-7972/? D/COPYDATABASE: Ateempting copy of block 15 which has 1024 bytes.
02-21 10:24:31.810 7972-7972/? D/COPYDATABASE: Ateempting copy of block 16 which has 1024 bytes.
02-21 10:24:31.810 7972-7972/? D/COPYDATABASE: Ateempting copy of block 17 which has 1024 bytes.
02-21 10:24:31.810 7972-7972/? D/COPYDATABASE: Ateempting copy of block 18 which has 1024 bytes.
02-21 10:24:31.810 7972-7972/? D/COPYDATABASE: Ateempting copy of block 19 which has 1024 bytes.
02-21 10:24:31.810 7972-7972/? D/COPYDATABASE: Ateempting copy of block 20 which has 1024 bytes.
02-21 10:24:31.810 7972-7972/? D/COPYDATABASE: Ateempting copy of block 21 which has 1024 bytes.
02-21 10:24:31.810 7972-7972/? D/COPYDATABASE: Ateempting copy of block 22 which has 1024 bytes.
02-21 10:24:31.810 7972-7972/? D/COPYDATABASE: Ateempting copy of block 23 which has 1024 bytes.
02-21 10:24:31.810 7972-7972/? D/COPYDATABASE: Ateempting copy of block 24 which has 1024 bytes.
02-21 10:24:31.811 7972-7972/? D/COPYDATABASE: Ateempting copy of block 25 which has 1024 bytes.
02-21 10:24:31.811 7972-7972/? D/COPYDATABASE: Ateempting copy of block 26 which has 1024 bytes.
02-21 10:24:31.811 7972-7972/? D/COPYDATABASE: Ateempting copy of block 27 which has 1024 bytes.
02-21 10:24:31.811 7972-7972/? D/COPYDATABASE: Ateempting copy of block 28 which has 1024 bytes.
02-21 10:24:31.811 7972-7972/? D/COPYDATABASE: Ateempting copy of block 29 which has 1024 bytes.
02-21 10:24:31.811 7972-7972/? D/COPYDATABASE: Ateempting copy of block 30 which has 1024 bytes.
02-21 10:24:31.811 7972-7972/? D/COPYDATABASE: Ateempting copy of block 31 which has 1024 bytes.
02-21 10:24:31.811 7972-7972/? D/COPYDATABASE: Ateempting copy of block 32 which has 1024 bytes.
02-21 10:24:31.811 7972-7972/? D/COPYDATABASE: Ateempting copy of block 33 which has 1024 bytes.
02-21 10:24:31.811 7972-7972/? D/COPYDATABASE: Ateempting copy of block 34 which has 1024 bytes.
02-21 10:24:31.811 7972-7972/? D/COPYDATABASE: Ateempting copy of block 35 which has 1024 bytes.
02-21 10:24:31.811 7972-7972/? D/COPYDATABASE: Ateempting copy of block 36 which has 1024 bytes.
02-21 10:24:31.811 7972-7972/? D/COPYDATABASE: Ateempting copy of block 37 which has 1024 bytes.
02-21 10:24:31.811 7972-7972/? D/COPYDATABASE: Ateempting copy of block 38 which has 1024 bytes.
02-21 10:24:31.812 7972-7972/? D/COPYDATABASE: Ateempting copy of block 39 which has 1024 bytes.
02-21 10:24:31.812 7972-7972/? D/COPYDATABASE: Ateempting copy of block 40 which has 1024 bytes.
02-21 10:24:31.812 7972-7972/? D/COPYDATABASE: Finished copying Database db from the assets folder, to  /data/data/so.cdfa/databases/db40960were copied, in 40 blocks of size 1024.
02-21 10:24:31.812 7972-7972/? D/COPYDATABASE: All Streams have been flushed and closed.

上面的代码是从整个 DBHelper 中提取的

日志将被删除，许多 cmets 发表评论并修复了一个问题，即可以清理代码。

public class DBHelper extends SQLiteOpenHelper {

    private static String DB_NAME = "db";
    private SQLiteDatabase myDataBase;
    private final Context myContext;

    private int bytes_copied = 0;
    private static int buffer_size = 1024;
    private int blocks_copied = 0;

    public DBHelper(Context context) {
        super(context, DB_NAME, null, 1);

        this.myContext = context;
        // Check for and create (copy DB from assets) when constructing the DBHelper
        if (!checkDataBase()) {
            bytes_copied = 0;
            blocks_copied = 0;
            createDataBase();
        }
    }

    /**
     * Creates an empty database on the system and rewrites it with your own database.
     * */
    public void createDataBase() {

        boolean dbExist = checkDataBase(); // Double check
        if(dbExist){
            //do nothing - database already exist
        } else {
            //By calling this method an empty database will be created into the default system path
            //of your application so we are gonna be able to overwrite that database with our database.
            //this.getReadableDatabase();
            //<<<<<<<<<< Dimsiss the above comment
            //By calling this method an empty database IS NOT created nor are the related -shm and -wal files
            //The method that creates the database is flawed and was only used to resolve the issue
            //of the copy failing in the absence of the databases directory.
            //The dbExist method, now utilised, checks for and creates the database directory, so there
            //is then no need to create the database just to create the databases library. As a result
            //the -shm and -wal files will not exist and thus result in the error associated with
            //Android 9+ failing with due to tables not existining after an apparently successful
            //copy.
            try {
                copyDataBase();
            } catch (IOException e) {
                File db = new File(myContext.getDatabasePath(DB_NAME).getPath());
                if (db.exists()) {
                    db.delete();
                }
                e.printStackTrace();
                throw new RuntimeException("Error copying database (see stack-trace above)");
            }
        }
    }

    /**
     * Check if the database already exist to avoid re-copying the file each time you open the application.
     * @return true if it exists, false if it doesn't
     */
    private boolean checkDataBase() {
        /**
         * Does not open the database instead checks to see if the file exists
         * also creates the databases directory if it does not exists
         * (the real reason why the database is opened, which appears to result in issues)
         */

        File db = new File(myContext.getDatabasePath(DB_NAME).getPath()); //Get the file name of the database
        Log.d("DBPATH","DB Path is " + db.getPath());
        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;
    }

    /**
     * Copies your database from your local assets-folder to the just created empty database in the
     * system folder, from where it can be accessed and handled.
     * This is done by transfering bytestream.
     * */
    private void copyDataBase() throws IOException {

        final String TAG = "COPYDATABASE";

        //Open your local db as the input stream
        Log.d(TAG,"Initiated Copy of the database file " + DB_NAME + " from the assets folder.");
        InputStream myInput = myContext.getAssets().open(DB_NAME); // Open the Asset file
        String dbpath = myContext.getDatabasePath(DB_NAME).getPath();
        Log.d(TAG,"Asset file " + DB_NAME + " found so attmepting to copy to " + dbpath);

        // Path to the just created empty db
        //String outFileName = DB_PATH + DB_NAME;
        //Open the empty db as the output stream
        File outfile = new File(myContext.getDatabasePath(DB_NAME).toString());
        Log.d("DBPATH","path is " + outfile.getPath());
        //outfile.setWritable(true); // NOT NEEDED as permission already applies
        //OutputStream myoutputx2 = new FileOutputStream(outfile);
        /* Note done in checkDatabase method
        if (!outfile.getParentFile().exists()) {
            outfile.getParentFile().mkdirs();
        }
        */

        OutputStream myOutput = new FileOutputStream(outfile);
        //transfer bytes from the inputfile to the outputfile
        byte[] buffer = new byte[buffer_size];
        int length;
        while ((length = myInput.read(buffer))>0) {
            blocks_copied++;
            Log.d(TAG,"Ateempting copy of block " + String.valueOf(blocks_copied) + " which has " + String.valueOf(length) + " bytes.");
            myOutput.write(buffer, 0, length);
            bytes_copied += length;
        }
        Log.d(TAG,
                "Finished copying Database " + DB_NAME +
                        " from the assets folder, to  " + dbpath +
                        String.valueOf(bytes_copied) + "were copied, in " +
                        String.valueOf(blocks_copied) + " blocks of size " +
                        String.valueOf(buffer_size) + "."
        );
        //Close the streams
        myOutput.flush();
        myOutput.close();
        myInput.close();
        Log.d(TAG,"All Streams have been flushed and closed.");
    }


    @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) {
    }

    @Override
    public void onConfigure(SQLiteDatabase db) {
        super.onConfigure(db);
        Log.d("DBCONFIGURE","Database has been configured ");
    }

    @Override
    public void onOpen(SQLiteDatabase db) {
        super.onOpen(db);
        Log.d("DBOPENED","Database has been opened.");
    }
}

【讨论】：

不。还是不行。我仍然得到 FileNotFoundException /data/data/...myDb.db: open failed: ENOTDIR (Not a directory)
@Jasonca1 在Log.d("DBPATH","DB Path is " + outfile.getPath()); 行之后立即添加Log.d("DBPATH","DB Path is " + outfile.getPath()); 行之后，您能否编辑您的问题以包含堆栈跟踪。
日志输出为：/data/data/com.myproject.myprojectpackage/databases/mydatabase.db
@Jasonca1 我相信你没有正确介绍目录创建代码，也许你离开了！？。答案已被修改以显示复制您的问题并且修复工作的代码。 （不是它不是最干净的代码，因为它是对我使用过的现有代码的改编（对于我给出的另一个答案））
我将尝试您修改后的解决方案并发布我的结果。

【解决方案2】：

错误提示找不到输出文件。因此，您需要先创建一个才能打开它并从资产中复制。

try {       
    String DB_PATH = "/data/data/" + "your.application.package.name" + "/databases/";
    File dir = new File(DB_PATH);
    if (!dir.exists()) dir.mkdir();
    File f = new File(DB_PATH + DB_NAME);
    if (!f.exists()) {
        f.createNewFile();
    }
} catch (Exception e) {
    e.printStackTrace();
}

// Then it should work
OutputStream mOutput = new FileOutputStream(f);

【讨论】：

createNewFile 函数调用失败
不应该。它可能会显示错误，此代码段可能会引发错误，使用 try/catch 块可以轻松避免该错误。我正在使用try/catch 块更新答案。请看一看。
@Raez Murshed 它仍然失败。仍然收到错误代码：java.io.IOException: open failed: ENOTDIR (Not a directory)
你能用你输出目录的代码段更新问题吗？好让我看看？您的应用程序包名称是什么？