将数据库从资产复制到单独应用程序的数据库文件夹

Question

正如我在其他地方看到的那样，我已经完成了以下两项工作。 该应用程序具有一个表示copy和onClick的按钮，它将把.db文件从正在运行的apk的资产目录中移动到该文件的数据库目录中。

我想知道是否有可能获取数据库文件并将其复制到应用程序的数据库目录，而不是当前正在运行的应用程序？

或者更明确地说，我的问题是有人可以给我一个示例或向我展示如何在下面编辑我的代码，以将复制的.db放置在与数据库复制和移动时当前正在运行的应用程序目录不同的应用程序目录中。做完了吗？

public class DatabaseHelper extends SQLiteOpenHelper{

//The Android's default system path of your application database.
private static String DB_PATH ="/data/data/com.rtt.bltc/databases/";
private static String DB_NAME = "ldeb.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;
    DB_PATH="/data/data/"+context.getPackageName()+"/"+"databases/";
    //DB_PATH="/data/data/com.rtt.bltc"+"/"+"databases/";
}

/ ** *在系统上创建一个空数据库，并用您自己的数据库重写它。 * * / public void createDataBase（）引发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){

        //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) {

}

//返回游标公共游标查询（字符串表，字符串[]列，字符串选择，字符串[] selectionArgs，字符串groupBy，字符串具有，字符串orderBy）{返回myDataBase.query（“ profiles”，null，null，null，null ，null，null）;

}

}

我在上面和下面都包含了CopyDb和Helper类的副本。

public class CopyDbActivity extends Activity {
/** Called when the activity is first created. */
Cursor c=null;
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    ((Button)findViewById(R.id.button01)).setOnClickListener(new View.OnClickListener(){
        @Override
        public void onClick(View v) {


             DatabaseHelper myDbHelper = new DatabaseHelper(CopyDbActivity.this);
             try {

                myDbHelper.createDataBase();

        } catch (IOException ioe) {

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

        }

        try {

            myDbHelper.openDataBase();

        }catch(SQLException sqle){

            throw sqle;

        }
        Toast.makeText(CopyDbActivity.this, "Success", Toast.LENGTH_SHORT).show();



        c=myDbHelper.query("profiles", null, null, null, null,null, null);
        if(c.moveToFirst())
        {
            do {

                Toast.makeText(CopyDbActivity.this,
                        "_id" + c.getString(0) + "\n" +
                        "UUID" + c.getString(1) + "\n" +
                        "NAME" + c.getString(2) + "\n" +
                         Toast.LENGTH_LONG).show();
                         } while (c.moveToNext());
                 }
             }
    });        
    }
   }

Answer 1

我想知道是否有可能获取数据库文件并将其复制到应用程序的数据库目录，而不是当前正在运行的应用程序？

不能。您的应用程序没有对内部存储器中另一个应用程序部分的读取权限，更不用说写入权限了。