Getting “Failed to open database” error when copyi

My Code works fine For Android 2.3 but i don't know why it doesn't work for Android 4.2

My Exception log is here

01-17 09:54:04.411: E/SQLiteLog(24202): (14) cannot open file at line 30176 of [00bb9c9ce4]
01-17 09:54:04.411: E/SQLiteLog(24202): (14) os_unix.c:30176: (2) open(/data/data/com.example.myapp/databases/myapp.db) - 
Failed to open database '/data/data/com.example.mypapp/databases/myapp.db'.
android.database.sqlite.SQLiteCantOpenDatabaseException: unknown error (code 14): Could not open database
at android.database.sqlite.SQLiteConnection.nativeOpen(Native Method)
at android.database.sqlite.SQLiteConnection.open(SQLiteConnection.java:209)
at android.database.sqlite.SQLiteConnection.open(SQLiteConnection.java:193)
at android.database.sqlite.SQLiteConnectionPool.openConnectionLocked(SQLiteConnectionPool.java:463)
at android.database.sqlite.SQLiteConnectionPool.open(SQLiteConnectionPool.java:185)
at android.database.sqlite.SQLiteConnectionPool.open(SQLiteConnectionPool.java:177)
at android.database.sqlite.SQLiteDatabase.openInner(SQLiteDatabase.java:804)
at android.database.sqlite.SQLiteDatabase.open(SQLiteDatabase.java:789)
at android.database.sqlite.SQLiteDatabase.openDatabase(SQLiteDatabase.java:694)
at android.database.sqlite.SQLiteDatabase.openDatabase(SQLiteDatabase.java:669)
at com.example.myapp.DataBaseHelper.checkDataBase(DataBaseHelper.java:80)
at com.example.myapp.DataBaseHelper.createDataBase(DataBaseHelper.java:47)
at com.example.myapp.MainActivity.onCreate(MainActivity.java:61)
at android.app.Activity.performCreate(Activity.java:5104)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
at android.app.ActivityThread.access$600(ActivityThread.java:141)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:5039)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
at dalvik.system.NativeStart.main(Native Method)

My MainActivity.java

public class MainActivity extends Activity {

    public void onCreate(Bundle icicle) {

        super.onCreate(icicle);

        setContentView(R.layout.activity_main);

        DataBaseHelper myDbHelper;
        myDbHelper = new DataBaseHelper(this);

        try {

            myDbHelper.createDataBase();

        } catch (IOException ioe) {         

            throw new Error("Unable to create database");
        }

        try {
            myDbHelper.openDataBase();

        } catch (SQLException sqle) {

            throw sqle;

        } finally {

            myDbHelper.close();
        }
}}

My DatabaseHelper.java

public class DataBaseHelper extends SQLiteOpenHelper{

    //The Android's default system path of your application database.
    private static String DB_PATH = "/data/data/com.example.myapp/databases/";

    private static String DB_NAME = "myapp.db";

    private SQLiteDatabase myDataBase; 

    private final Context myContext;

    /**
     * Constructor
     * Takes and keeps a reference of the passed context in order to access to the application assets and resources.
     * @param context
     */
    public DataBaseHelper(Context context) {

        super(context, DB_NAME, null, 1);
        this.myContext = context;
    }   

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

        boolean dbExist = checkDataBase();

        if(dbExist){
            //do nothing - database already exist
        }else{

            //By calling this method and 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();

            try {

                copyDataBase();

            } catch (IOException e) {

                throw new Error("Error copying database");

            }
        }

    }

    /**
     * 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(){

        SQLiteDatabase checkDB = null;

        try{
            String myPath = DB_PATH + DB_NAME;
            checkDB = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);

        }catch(SQLiteException e){  
            Log.i("Hellloooo", e.getMessage());
            //database does't exist yet.

        }

        if(checkDB != null){

            checkDB.close();

        }

        return checkDB != null ? true : 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{

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

        // Path to the just created empty db
        String outFileName = DB_PATH + DB_NAME;

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

        //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();

    }

    public void openDataBase() throws SQLException{

        //Open the database
        String myPath = DB_PATH + DB_NAME;
        myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);

    }

    @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) {

    }

        // Add your public helper methods to access and get content from the database.
       // You could return cursors by doing "return myDataBase.query(....)" so it'd be easy
       // to you to create adapters for your views.

}

回答1:

I had to modify checkDataBase() to

 private boolean checkDataBase() {
    File databasePath = mContext.getDatabasePath(DB_NAME);
    return databasePath.exists();
}

回答2:

I faced this problem, it was because in 4.2, there is multi users support, and if you are testing with non-admin user, you cannot acess /data/data path..

In my case i'm using the path:

context.getFilesDir().getAbsolutePath().replace("files", "databases") + File.separator

Hope that helps..

回答3:

Some devices cannot handle large assets. What I did is split database to 1 MiB chunks and copied them to a file

I created a script (for Linux) to easily split the file

#!/bin/bash

#split database file into chunks not larger than 1 MiB
split -b 1048576 databasename db -d -a1

The chunks will be named db0, db1, db2, ..., dbN

/**
 * Copies database from assets to a file if not exists.
 * 
 * @param context Application's Context
 */
public static void copyDatabase(Context context)
{

    File target = context.getDatabasePath(databasename");
    if (target.exists()) {
        return;
    }

    target.getParentFile().mkdirs();

    InputStream is = null;
    OutputStream os = null;
    try {
        List<String> filesl = new ArrayList<String>();
        String[] files = context.getAssets().list("");
        if (files != null) {
            for (int i = 0; i < files.length; i++) {
                if (Pattern.matches("^db\\d.db$", files[i])) {
                    filesl.add(files[i]);
                }
            }
        }
        files = null;
        Collections.sort(filesl);

        if (filesl.isEmpty()) {
            return;
        }

        os = new FileOutputStream(target);

        for (int i = 0; i < filesl.size(); i++) {
            is = context.getAssets().open(filesl.get(i),
                    AssetManager.ACCESS_BUFFER);

            byte[] buffer = new byte[5096];
            int read;

            while (true) {
                read = is.read(buffer, 0, buffer.length);
                if (read < 0)
                    break;
                os.write(buffer, 0, read);
            }
            is.close();
        }

    } catch (Exception e) {
        if (target.exists()) {
            target.delete();
        }
        e.printStackTrace();
    } finally {
        if (is != null)
            try {
                is.close();
            } catch (Exception e) {
            }
        if (os != null)
            try {
                os.close();
            } catch (Exception e) {
            }
    }
}

Note that Collections.sort will sort names in proper order if not more that 10 files in case db0 ...db9 - after db10 your will have to write your own sorting or comarator.