errorCopyingDatabase從資產文件夾到內存

Question

我正在關注此鏈接以打開與數據庫的連接。但是，當我嘗試打開它時，它會拋出一個異常，指出errorCopyingDatabase。我的數據庫大小大約爲20MB。是否由於它沒有從Assets文件夾複製到內存或其他問題的大小。我相信我的代碼很好，我也仔細檢查了所有的路徑（一切似乎都很好）。我得到以下異常：

12-14 04:44:45.471: E/AndroidRuntime(512): java.lang.Error: ErrorCopyingDataBase 
12-14 04:44:45.471: E/AndroidRuntime(512): at com.bondsms.db.DBHelper.createDataBase(DBHelper.java:42) 
12-14 04:44:45.471: E/AndroidRuntime(512): at com.bondsms.db.DBAdapter.createDatabase(DBAdapter.java:37) 
12-14 04:44:45.471: E/AndroidRuntime(512): at com.bondsms.BSGroupsActivity.loadAllGroupsFromDB(BSGroupsActivity.java:98) 
12-14 04:44:45.471: E/AndroidRuntime(512): at com.bondsms.BSGroupsActivity.onCreate(BSGroupsActivity.java:55) 
12-14 04:44:45.471: E/AndroidRuntime(512): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047) 
12-14 04:44:45.471: E/AndroidRuntime(512): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627) 
12-14 04:44:45.471: E/AndroidRuntime(512): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679) 
12-14 04:44:45.471: E/AndroidRuntime(512): at android.app.ActivityThread.access$2300(ActivityThread.java:125) 
12-14 04:44:45.471: E/AndroidRuntime(512): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033) 
12-14 04:44:45.471: E/AndroidRuntime(512): at android.os.Handler.dispatchMessage(Handler.java:99) 
12-14 04:44:45.471: E/AndroidRuntime(512): at android.os.Looper.loop(Looper.java:123) 
12-14 04:44:45.471: E/AndroidRuntime(512): at android.app.ActivityThread.main(ActivityThread.java:4627) 
12-14 04:44:45.471: E/AndroidRuntime(512): at java.lang.reflect.Method.invokeNative(Native Method) 
12-14 04:44:45.471: E/AndroidRuntime(512): at java.lang.reflect.Method.invoke(Method.java:521) 
12-14 04:44:45.471: E/AndroidRuntime(512): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868) 
12-14 04:44:45.471: E/AndroidRuntime(512): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626) 
12-14 04:44:45.471: E/AndroidRuntime(512): at dalvik.system.NativeStart.main(Native Method) 

Answer 1

我已經嘗試了很多的時間來複制從資產數據庫，這是我的同班同學複製，它的作品對我很好，你可以使用它，也許這有助於（記住更改DB_PATH =「/ data/data/[your package]/databases /」，DB_NAME =資產中的數據名稱）。

public class DatabaseController extends SQLiteOpenHelper { 

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

    private static final String DB_NAME = "HanoiFood.sqlite"; 

    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 DatabaseController(Context context) { 
     super(context, DB_NAME, null, 1); 
     this.myContext = context; 
     try { 
      createDataBase(); 
     } catch (IOException ioe) { 
      throw new Error("Unable to create database"); 
     } 
    } 

    /** 
    * 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 
      myDataBase = getWritableDatabase(); 
     } else { 
      myDataBase = getWritableDatabase(); 
      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 (Exception 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_READWRITE); 

    } 

    public Cursor query(String table, String[] columns, String selection, 
      String[] selectionArgs, String groupBy, String having, 
      String orderBy) { 
     myDataBase = getWritableDatabase(); 
     Cursor cursor = myDataBase.query(table, columns, selection, 
       selectionArgs, groupBy, having, orderBy); 
     if (cursor == null) { 
      return null; 
     } else if (!cursor.moveToFirst()) { 
      cursor.close(); 
      return null; 
     } 
     return cursor; 
    } 

    public long insert(String table, String nullColumnHack, ContentValues values) { 
     long insertRet = myDataBase.insert(table, nullColumnHack, values); 
     if (insertRet == -1) { 
      Log.d("DungHV", "Insert db error"); 
     } 
     return insertRet; 
    } 

    @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) { 
     // TODO Auto-generated method stub 
    } 
} 

在你的活動簡單的調用：

DatabaseContrller mdb = new DatabaseController(getApplicationContext());