先前創建的SQLite數據庫無法訪問

Question

我創造，我要打開一個以前創建的SQLite數據庫的應用程序。我正在使用DBHelper類。一切都很好，當我模仿的應用程序，但logcat的是顯示以下錯誤：

10-31 17:59:56.345: I/Database(391): sqlite returned: error code = 14, msg = cannot open file at source line 25467 
10-31 17:59:56.345: E/Database(391): sqlite3_open_v2("/data/data/com.proj.neuroq/databases/quiz.db", &handle, 1, NULL) failed 

我的動態類：

public class QuestionActivity extends Activity { 

    String db_name="quiz"; 

    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_question); 

     DatabaseHelper myDbHelper = new DatabaseHelper(getBaseContext()); 
     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; 

    } 



    } 

    @Override 
    public boolean onCreateOptionsMenu(Menu menu) { 
     getMenuInflater().inflate(R.menu.activity_question, menu); 
     return true; 
    } 


} 

我DatabaseHelper類：

public class DatabaseHelper extends SQLiteOpenHelper { 

    private static String DB_PATH = "/data/data/com.proj.neuroq/databases/"; 
    private static String DB_NAME = "quiz.db"; 
    private SQLiteDatabase db; 
    private final Context myContext; 

    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 dosen'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) { 

     } 

     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; 
     db = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY); 
    } 

    @Override 
    public synchronized void close() { 
     if(db != null) 
      db.close(); 

     super.close(); 
    } 

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

    } 

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

    } 

} 

我的清單文件：

<manifest xmlns:android="http://schemas.android.com/apk/res/android" 
    package="com.proj.neuroq" 
    android:versionCode="1" 
    android:versionName="1.0" > 

    <uses-sdk 
     android:minSdkVersion="8" 
     android:targetSdkVersion="15" /> 

    <application 
     android:icon="@drawable/ic_launcher" 
     android:label="@string/app_name" 
     android:theme="@style/AppTheme" > 
     <activity 
      android:name=".QuestionActivity" 
      android:label="@string/title_activity_question" > 
      <intent-filter> 
       <action android:name="android.intent.action.MAIN" /> 

       <category android:name="android.intent.category.LAUNCHER" /> 
      </intent-filter> 
     </activity> 
    </application> 

</manifest> 

這是我的項目結構：

這是我logcat的輸出：

我曾提到的鏈接：

http://www.reigndesign.com/blog/using-your-own-sqlite-database-in-android-applications/

http://snipplr.com/view.php?codeview&id=58589

凡位於棘手的問題？

Answer 1

你應該是這樣的替換您的checkDataBase（）方法：

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

在這篇文章中提出：http://www.itsalif.info/content/check-if-database-exist-android-sqlite3openv2-failed