android - 为 Android 应用程序复制 Sqlite 数据库

Question

我正在尝试使用本教程在我的 Android 应用程序中使用我自己创建的数据库 http://www.reigndesign.com/blog/using-your-own-sqlite-database-in-android-applications/

我的 Assets 文件夹中有我的数据库已经工作了 5 个小时来解决问题但徒劳无功..我总是不断得到

01-17 04:09:07.111: E/Database(1060): sqlite3_open_v2("/data/data/com.rahul.besttracker/databases/route", &handle, 1, NULL) failed

和

01-17 04:09:07.271: E/AndroidRuntime(1060): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.rahul.besttracker/com.rahul.besttracker.Busdisplay}: android.database.sqlite.SQLiteException: unable to open database file

我的代码

public class Busdisplay extends ListActivity {
    TextView source, destination;
    String src, dest;
    ArrayList<String> mArrayList;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);

        init();
        Bundle caught = getIntent().getExtras();
        src = caught.getString("source");
        dest = caught.getString("dest");

        DataBaseHelper entry = null;

        entry = new DataBaseHelper(Busdisplay.this);

        entry.openDataBase();

        mArrayList = entry.readEntry(src, dest);

        entry.close();

        setListAdapter(new ArrayAdapter<String>(this,
                android.R.layout.simple_list_item_1, mArrayList));
    }

    @Override
    protected void onListItemClick(ListView l, View v, int position, long id) {
        // TODO Auto-generated method stub
        super.onListItemClick(l, v, position, id);
    }

    void init() {
        source = (TextView) findViewById(R.id.textView1);
        destination = (TextView) findViewById(R.id.textView2);
    }

}

我的 DBhelper 类

public class DataBaseHelper extends SQLiteOpenHelper {

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

    private static final String DB_NAME = "route.db";
    private static final String DB_TABLE1 = "route1";
    private static final String DB_TABLE2 = "route2";
    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) {

            System.out.print("ERROR");
        }

        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) {
        try {
            createDataBase();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        db.execSQL("DROP TABLE IF EXISTS " + DB_TABLE1);
        db.execSQL("DROP TABLE IF EXISTS " + DB_TABLE2);
        onCreate(db);
    }

    public ArrayList<String> readEntry(String src, String dest) {

        // TODO Auto-generated method stub
        Cursor c = myDataBase.rawQuery("SELECT route_no from " + DB_TABLE1
                + " WHERE stops LIKE '%" + src + "%,%" + dest + "%';", null);
        ArrayList<String> mArrayList = new ArrayList<String>();
        int index = c.getColumnIndex("route_no");
        for (c.moveToFirst(); !c.isAfterLast(); c.moveToNext()) {
            // The Cursor is now set to the right position
            mArrayList.add(c.getString(index));
        }
        return mArrayList;
    }

    // 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.

}

Answer 1

我什至遇到了同样的问题，对此感到非常沮丧，即使我使用了本教程，但它没有用。我搜索了很多关于这个的话题并找到了一个......即使这不起作用......但我做了一个简单的改变。首先，创建两个类 DatabaseHelper 和 CopyAdapter:

数据库助手

    public class DatabaseHelper extends SQLiteOpenHelper{
private static String TAG = "TAG";
private static String DB_PATH = "/data/data/PLACE_HERE_YOUR_INTERNAL_PATH/databases/";
private static String DB_NAME = "PLACE_HERE_YOUR_DATABASE_NAME_WITH_EXTENSION";
private SQLiteDatabase mDataBase; 
private final Context mContext;

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
{
    boolean mDataBaseExist = checkDataBase();
    Log.d(TAG,"create DB in Helper. Data exists?"+mDataBaseExist);
    if(!mDataBaseExist)
    {
        Log.d(TAG,"get Writable in DatabaseHelper");
        this.getWritableDatabase();
        try 
        {
            Log.d(TAG,"copy Database");
            copyDataBase();
        } 
        catch (IOException mIOException) 
        {Log.d(TAG,"copy not succeed");
            throw new Error("ErrorCopyingDataBase");

        }
    }
}

private boolean checkDataBase()
{
    SQLiteDatabase mCheckDataBase = null;
    try
    {
        String myPath = DB_PATH + DB_NAME;
        mCheckDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.NO_LOCALIZED_COLLATORS);
    }
    catch(SQLiteException mSQLiteException)
    {
        Log.e(TAG, "DatabaseNotFound " + mSQLiteException.toString());
    }

    if(mCheckDataBase != null)
    {
        mCheckDataBase.close();
    }
    return mCheckDataBase != null;
}

private void copyDataBase() throws IOException
{
    Log.d(TAG,"copy");
    InputStream mInput = mContext.getResources().getAssets().open(DB_NAME);

    String outFileName = DB_PATH + DB_NAME;
    Log.d(TAG,"Output:"+outFileName);
    File createOutFile = new File(outFileName);
    if(!createOutFile.exists()){
        createOutFile.mkdir();
    }
    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();
}

public boolean openDataBase() throws SQLException
{
    String mPath = DB_PATH + DB_NAME;
    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 onCreate(SQLiteDatabase db) 
{ }

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) 
{
    Log.vTAG, "UpgradingDatabase, This will drop current database and will recreate it");
}
   }

复制适配器

    public class CopyAdapter {

private final Context mContext;
private SQLiteDatabase mDb;
private DatabaseHelper mDbHelper;
    private static String TAG = "TAG";
private static String ACCOUNT_TABLE = "account";
public static String ACCOUNT_EXTRADATA = "extraData";
public static String ACCOUNT_ID = "ID";
public static String ACCOUNT_ADDITIONALDATA = "additionalData";
public static String ACCOUNT_DATA = "data";

public CopyAdapter(Context context) 
{
    this.mContext = context;
    mDbHelper = new DatabaseHelper(mContext);
    Log.d(TAG,"done");
}

public CopyAdapter createDatabase() throws SQLException 
{
    try 
    {
        Log.d(TAG,"create database");
        mDbHelper.createDataBase();
    } 
    catch (IOException mIOException) 
    {
        Log.e(TAG, mIOException.toString() + "  UnableToCreateDatabase");
        throw new Error("UnableToCreateDatabase");
    }
    return this;
}

public CopyAdapter open() throws SQLException 
{
    try 
    {
        Log.d(TAG,"Open");
        mDbHelper.openDataBase();
        mDbHelper.close();
        mDb = mDbHelper.getWritableDatabase();
    } 
    catch (SQLException mSQLException) 
    {
        Log.e(TAG, mSQLException.toString());
        throw mSQLException;
    }
    return this;
}

public void close() 
{
    mDbHelper.close();
}

public int countAccountData() 
{
    Cursor mCoursor = mDb.query(ACCOUNT_TABLE, new String[] {}, null, null, null, null, null);
    int mReturnedCount = mCoursor.getCount();
    mCoursor.close();
    return mReturnedCount;
}

public long insertData(String mExtra, String mAdditionalData, String mData) 
{
    ContentValues initialValues = new ContentValues();
    initialValues.put(ACCOUNT_EXTRADATA, mExtra);
    initialValues.put(ACCOUNT_ADDITIONALDATA, mAdditionalData);
    initialValues.put(ACCOUNT_DATA, mData);
    return mDb.insert(ACCOUNT_TABLE, null, initialValues);
}

public boolean updateData(int mPosition, String mExtra, String mAdditionalData, String mData) 
{
    ContentValues initialValues = new ContentValues();
    initialValues.put(ACCOUNT_EXTRADATA, mExtra);
    initialValues.put(ACCOUNT_ADDITIONALDATA, mAdditionalData);
    initialValues.put(ACCOUNT_DATA, mData);
    return mDb.update(ACCOUNT_TABLE, initialValues, "ID=" + mPosition, null) > 0;
}

public String retriveData(int mPosition)
{
    Cursor mCursor = mDb.query(ACCOUNT_TABLE, new String[] {ACCOUNT_DATA}, "ID=" + mPosition, null, null, null, null);
    mCursor.moveToFirst();
    String mReturn = mCursor.getString(mCursor.getColumnIndex(ACCOUNT_DATA));
    mCursor.close();
    return mReturn;
}

public String retriveAdditionalData(int mPosition)
{
    Cursor mCursor = mDb.query(ACCOUNT_TABLE, new String[] {ACCOUNT_ADDITIONALDATA}, "ID=" + mPosition, null, null, null, null);
    mCursor.moveToFirst();
    String mReturn = mCursor.getString(mCursor.getColumnIndex(ACCOUNT_ADDITIONALDATA));
    mCursor.close();
    return mReturn;
}

public boolean deleteAccount(int mPosition) 
{
    return mDb.delete(ACCOUNT_TABLE, ACCOUNT_ID + "=" + mPosition, null) > 0;
}
   }

然后只需在您需要的地方调用:

   CopyAdapter  mDbHelper = new CopyAdapter(YourActivity.this);
    mDbHelper.createDatabase();

并确保你设置了

    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

在你的 manifest.xml 中

例如，我阅读了很多变体，将您的数据库文件放在 Assets 文件夹中的另一个文件夹中，或者将您的数据库文件的结尾重命名为 jpg，或者在将其添加到 Assets 之前将您的数据库文件压缩......忘记了那。我能够使我的应用程序正常工作的唯一方法是将数据库文件不带文件夹或重命名或压缩到我的 Assets 文件夹中。只是纯文件。从这一点开始，它工作没有问题。

我不知道我从哪里得到上面的这个例子，我再也找不到这个网站了(但它在 stackoverflow 上)，但是这个，有一点解决方法并将纯数据库文件放在 Assets 文件夹中，是解决方案。希望对您有所帮助..