ErrorCopyingDataBase異常，當我嘗試打開一個SQLite數據庫

Question

當我嘗試打開該資產的文件夾中的數據庫與方法

public void loadDatabase(String dbName){ 
    System.out.println("dbName"); 
    DataBaseAdapterNew mDbHelper = new DataBaseAdapterNew(
        this, dbName); 
      mDbHelper.createDatabase(); 
      mDbHelper.open(); 

    } 

我得到一個致命的異常ErrorCopyingDataBase

錯誤堆棧

12-13 18:21:29.179: E/AndroidRuntime(10230): FATAL EXCEPTION: main 
12-13 18:21:29.179: E/AndroidRuntime(10230): java.lang.Error: ErrorCopyingDataBase 
12-13 18:21:29.179: E/AndroidRuntime(10230): at com.my.app.db.DataBaseHelper.createDataBase(DataBaseHelper.java:43) 
12-13 18:21:29.179: E/AndroidRuntime(10230): at com.my.app.db.DataBaseAdapterNew.createDatabase(DataBaseAdapterNew.java:42) 
12-13 18:21:29.179: E/AndroidRuntime(10230): at com.my.app.MyActivity.loadDatabase(MyActivity.java:133) 
12-13 18:21:29.179: E/AndroidRuntime(10230): at com.my.app.MyActivity$InvocazioneAsincrona$1.run(MyActivity.java:173) 
12-13 18:21:29.179: E/AndroidRuntime(10230): at android.os.Handler.handleCallback(Handler.java:587) 
12-13 18:21:29.179: E/AndroidRuntime(10230): at android.os.Handler.dispatchMessage(Handler.java:92) 
12-13 18:21:29.179: E/AndroidRuntime(10230): at android.os.Looper.loop(Looper.java:130) 
12-13 18:21:29.179: E/AndroidRuntime(10230): at android.app.ActivityThread.main(ActivityThread.java:3687) 
12-13 18:21:29.179: E/AndroidRuntime(10230): at java.lang.reflect.Method.invokeNative(Native Method) 
12-13 18:21:29.179: E/AndroidRuntime(10230): at java.lang.reflect.Method.invoke(Method.java:507) 
12-13 18:21:29.179: E/AndroidRuntime(10230): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:867) 
12-13 18:21:29.179: E/AndroidRuntime(10230): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:625) 
12-13 18:21:29.179: E/AndroidRuntime(10230): at dalvik.system.NativeStart.main(Native Method) 

我的DatabaseAdapterNew類是：

public class DataBaseAdapterNew { 

    protected static final String TAG = "DataAdapter"; 

    private final Context mContext; 
    private SQLiteDatabase mDb; 
    private DataBaseHelper mDbHelper; 

    public DataBaseAdapterNew(Context context, String nameDB) { 
     this.mContext = context; 
     mDbHelper = new DataBaseHelper(mContext, nameDB); 
    } 

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

    public DataBaseAdapterNew open() throws SQLException { 
     try { 
      mDbHelper.openDataBase(); 
      mDbHelper.close(); 
      mDb = mDbHelper.getReadableDatabase(); 
     } catch (SQLException mSQLException) { 
      Log.e(TAG, "open >>" + mSQLException.toString()); 
      throw mSQLException; 
     } 
     return this; 
    } 

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

    public Cursor allData() { 
     try { 
      Cursor c = mDb.rawQuery(
        "SELECT * FROM myTable order by Quantity desc", null); 
      if (c != null) { 
       c.moveToNext(); 
      } 
      return c; 
     } catch (SQLException mSQLException) { 
      Log.e(TAG, "allData >>" + mSQLException.toString()); 
      throw mSQLException; 
     } 

    } 



    } 

我DatabaseHelper類是：

public class DataBaseHelper extends SQLiteOpenHelper { 
    private static String TAG = "DataBaseHelper"; 
    private static String DB_PATH = ""; 
    private static String DB_NAME = ""; 
    private SQLiteDatabase mDataBase; 
    private final Context mContext; 

    public DataBaseHelper(Context context, String nomeDB) { 
     super(context, nomeDB, null, 1);// 1? its Database Version 
     DB_NAME = nomeDB; 
     DB_PATH = "/data/data/" + context.getPackageName() + "/databases/"; 
     this.mContext = context; 
    } 

    public void createDataBase() throws IOException { 
     // If database not exists copy it from the assets 

     boolean mDataBaseExist = checkDataBase(); 
     if (!mDataBaseExist) { 
      this.getReadableDatabase(); 
      this.close(); 
      try { 
       // Copia il database dalla cartella assests 
       copyDataBase(); 
       Log.e(TAG, "createDatabase database created"); 
      } catch (IOException mIOException) { 
       throw new Error("ErrorCopyingDataBase"); 
      } 
     } 
    } 

    private boolean checkDataBase() { 
     File dbFile = new File(DB_PATH + DB_NAME); 
     return dbFile.exists(); 
    } 

    private void copyDataBase() throws IOException { 
     InputStream mInput = mContext.getAssets().open(DB_NAME); 
     String outFileName = DB_PATH + DB_NAME; 
     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.CREATE_IF_NECESSARY); 
     return mDataBase != null; 
    } 

    @Override 
    public synchronized void close() { 
     if (mDataBase != null) 
      mDataBase.close(); 
     super.close(); 
    } 

    @Override 
    public void onCreate(SQLiteDatabase arg0) { 
     // TODO Auto-generated method stub 

    } 

    @Override 
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { 
     // TODO Auto-generated method stub 

    } 

} 

傳遞的字符串DBNAME顯示存在於資產的println文件夾中的DB的正確名稱，該數據庫是非零和預編譯，所以我無法弄清楚錯誤的原因。 有什麼建議嗎？

Answer 1

我將你的代碼複製到我的項目中，並且它能正常工作。

在loadDatabase（），

System.out.println("dbName"); 

將始終打印字DBNAME。我不確定這是否是資產文件夾中數據庫的名稱;因爲我看不到你對loadDatabase（dbName）的調用，所以我不知道你使用的是什麼值。

這是我如何調用你的代碼，直接從我的應用程序：

String dbName = "itr"; 
    System.out.println(dbName); 
    DataBaseAdapterNew mDbHelper = new DataBaseAdapterNew(
        this, dbName); 
      mDbHelper.createDatabase(); 
      mDbHelper.open(); 

在DatabaseHelper.createDataBase（），你是隱藏的錯誤條件。如果你想看到什麼異常原因造成的問題，我建議

public void createDataBase() throws IOException { 
    // If database not exists copy it from the assets 

    boolean mDataBaseExist = checkDataBase(); 
    if (!mDataBaseExist) { 
     this.getReadableDatabase(); 
     this.close(); 
     try { 
      // Copia il database dalla cartella assests 
      copyDataBase(); 
      Log.e(TAG, "createDatabase database created"); 
     } catch (IOException mIOException) { 
      Log.e(TAG, mIOException.toString()); 
      throw mIOException; 
     } 
    } 
} 

印刷在例外

java.io.FileNotFoundException：ITR UnableToCreateDatabase

我複製過來的現有的數據庫到/ assets/itr和我的數據庫被正確創建。