如何在android中解决错误复制数据库错误?

时间:2012-08-23 07:29:04

标签: android

我在4.0版本中创建了一个android应用程序,并将我的sqlite数据库保存在assets文件夹中。当我试图在2.3版本中运行我的应用程序时,我收到错误“错误复制数据库”。我试图将checkdatabase方法更改为以下但仍然无法正常工作。关于这个问题,任何人都可以指导我。

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

DBadapter.java

public class DBAdapter扩展了SQLiteOpenHelper {

private static String DB_PATH = "";
private static final String DB_NAME = "mydatabase.sqlite";
private SQLiteDatabase myDataBase1;
private final Context myContext1;

private static DBAdapter mDBConnection;

/**
 * Constructor 
 * Takes and keeps a reference of the passed context in order to access to the application assets and resources.
 * @param context
 */
private DBAdapter(Context context) {
    super(context, DB_NAME, null, 1);
    this.myContext1 = context;
    DB_PATH = "/data/data/"
            + context.getApplicationContext().getPackageName()
            + "/databases/";
    // The Android's default system path of your application database is
    // "/data/data/mypackagename/databases/"

}

/**
 * getting Instance
 * @param context
 * @return DBAdapter
 */
public static synchronized DBAdapter getDBAdapterInstance(Context context) {
    if (mDBConnection == null) {
        mDBConnection = new DBAdapter(context);
    }
    return mDBConnection;
}

/**
 * Creates an 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 following method 
        // 1) an empty database will be created into the default system path of your application 
        // 2) than we 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;
} 




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


/**
 * 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 = myContext1.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();
}

/**
 * Open the database
 * @throws SQLException
 */
public void openDataBase() throws SQLException {
    String myPath = DB_PATH + DB_NAME;
    myDataBase1 = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READWRITE);     
}

/**
 * Close the database if exist
 */
@Override
public synchronized void close() {
    if (myDataBase1 != null)
        myDataBase1.close();
    super.close();
}

/**
 * Call on creating data base for example for creating tables at run time
 */
@Override
public void onCreate(SQLiteDatabase db) {
}

/**
 * can used for drop tables then call onCreate(db) function to create tables again - upgrade
 */
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {


}



// ----------------------- CRUD Functions ------------------------------

/**
 * This function used to select the records from DB.
 * @param tableName
 * @param tableColumns
 * @param whereClase
 * @param whereArgs
 * @param groupBy
 * @param having
 * @param orderBy
 * @return A Cursor object, which is positioned before the first entry.
 */
public Cursor selectRecordsFromDB(String tableName, String[] tableColumns,
        String whereClase, String whereArgs[], String groupBy,
        String having, String orderBy) {
    return myDataBase1.query(tableName, tableColumns, whereClase, whereArgs,
            groupBy, having, orderBy);
}

/**
 * select records from db and return in list
 * @param tableName
 * @param tableColumns
 * @param whereClase
 * @param whereArgs
 * @param groupBy
 * @param having
 * @param orderBy
 * @return ArrayList<ArrayList<String>>
 */
public ArrayList<ArrayList<String>> selectRecordsFromDBList(String tableName, String[] tableColumns,
        String whereClase, String whereArgs[], String groupBy,
        String having, String orderBy) {        

    ArrayList<ArrayList<String>> retList = new ArrayList<ArrayList<String>>();
      ArrayList<String> list = new ArrayList<String>();
      Cursor cursor = myDataBase1.query(tableName, tableColumns, whereClase, whereArgs,
                groupBy, having, orderBy);        
      if (cursor.moveToFirst()) {
         do {
             list = new ArrayList<String>();
             for(int i=0; i<cursor.getColumnCount(); i++){                   
                 list.add( cursor.getString(i) );
             }   
             retList.add(list);
         } while (cursor.moveToNext());
      }
      if (cursor != null && !cursor.isClosed()) {
         cursor.close();
      }
      return retList;

}   

/**
 * This function used to insert the Record in DB. 
 * @param tableName
 * @param nullColumnHack
 * @param initialValues
 * @return the row ID of the newly inserted row, or -1 if an error occurred
 */
public long insertRecordsInDB(String tableName, String nullColumnHack,
        ContentValues initialValues) {
    return myDataBase1.insert(tableName, nullColumnHack, initialValues);
}

/**
 * This function used to update the Record in DB.
 * @param tableName
 * @param initialValues
 * @param whereClause
 * @param whereArgs
 * @return true / false on updating one or more records
 */
/*public boolean updateRecordInDB(String tableName,
        ContentValues initialValues, String whereClause, String whereArgs[]) {
    return myDataBase.update(tableName, initialValues, whereClause,
            whereArgs) > 0;             
}*/

/**
 * This function used to update the Record in DB.
 * @param tableName
 * @param initialValues
 * @param whereClause
 * @param whereArgs
 * @return 0 in case of failure otherwise return no of row(s) are updated
 */
/*public int updateRecordsInDB(String tableName,
        ContentValues initialValues, String whereClause, String whereArgs[]) {
    return myDataBase.update(tableName, initialValues, whereClause, whereArgs);     
}*/

/**
 * This function used to delete the Record in DB.
 * @param tableName
 * @param whereClause
 * @param whereArgs
 * @return 0 in case of failure otherwise return no of row(s) are deleted.
 */
/*public int deleteRecordInDB(String tableName, String whereClause,
        String[] whereArgs) {
    return myDataBase.delete(tableName, whereClause, whereArgs);
}*/

// --------------------- Select Raw Query Functions ---------------------

/**
 * apply raw Query
 * @param query
 * @param selectionArgs
 * @return Cursor
 */
public Cursor selectRecordsFromDB(String query, String[] selectionArgs) {
    return myDataBase1.rawQuery(query, selectionArgs);      
}

/**
 * apply raw query and return result in list
 * @param query
 * @param selectionArgs
 * @return ArrayList<ArrayList<String>>
 */
public ArrayList<ArrayList<String>> selectRecordsFromDBList(String query, String[] selectionArgs) {       
      ArrayList<ArrayList<String>> retList = new ArrayList<ArrayList<String>>();
      ArrayList<String> list = new ArrayList<String>();
      Cursor cursor = myDataBase1.rawQuery(query, selectionArgs);           
      if (cursor.moveToFirst()) {
         do {
             list = new ArrayList<String>();
             for(int i=0; i<cursor.getColumnCount(); i++){                   
                 list.add( cursor.getString(i) );
             }   
             retList.add(list);
         } while (cursor.moveToNext());
      }
      if (cursor != null && !cursor.isClosed()) {
         cursor.close();

      }
      return retList;
   }

}

提前致谢

3 个答案:

答案 0 :(得分:0)

<强> CheckDatabase

    private boolean checkDataBase() {
    SQLiteDatabase checkDB = null;
    try {
        String myPath = DB_PATH + DB_NAME;
        checkDB = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READWRITE);
        } catch (SQLiteException e) {
        // database does't exist yet.
        }
    if (checkDB != null) {
        checkDB.close();
    }
    return checkDB != null ? true : false;
}

更改:

super(context, DB_NAME, null, 1); 

致:

 super(context, DB_NAME, null, 2);

<强>的CreateDatabase

public void createDataBase() throws IOException {
    boolean dbExist = checkDataBase();
    if (dbExist) {
        // do nothing - database already exist
          // check if we need to upgrade
        openDataBase();
        int cVersion = myDataBase.getVersion();
        if(cVersion != 2){
            onUpgrade(myDataBase, myDataBase.getVersion(), 2);}
        close();
    } 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");
            }
        }
}

如果数据库已升级,则可以创建onUpgrade函数。我希望这有帮助。如果我遗漏了任何东西,请告诉我。

答案 1 :(得分:0)

尝试使用

   checkDB = SQLiteDatabase.openDatabase(myPath, null,
        SQLiteDatabase.CREATE_IF_NECESSARY);

而不是

checkDB = SQLiteDatabase.openDatabase(myPath, null,
                SQLiteDatabase.OPEN_READONLY);

答案 2 :(得分:0)

检查以下链接。此方法在4.0和2.3上进行测试。

using a preloaded sqlite database with SqliteOpenHelper