내부 저장소에서 내 응용 프로그램의 데이터 디렉터리로 데이터베이스 복사

Question

내부 저장소 디렉터리에서 내 응용 프로그램의 데이터 폴더로 데이터베이스 파일을 복사하려고합니다. 내가 copydatabase 함수를 호출하는 동안 컴파일러가 data.canWrite()가 false를 반환에 도달하면,

public static void copyDatabase(Context applicationContext){ 
    try { 
     File sd = Environment.getExternalStorageDirectory(); 
     File data = Environment.getDataDirectory(); 
     if (data.canWrite()) { 
      String dbPath = "/data/data/" + "my.package.here" + "/databases/dbname"; 
      String actualDBPath = "dbname.sqlite"; 
      File finalDB = new File(dbPath); 
      File actualDB = new File(sd, actualDBPath); 
      if (actualDB.exists()) { 
       FileChannel src = new FileInputStream(actualDB).getChannel(); 
       FileChannel dst = new FileOutputStream(finalDB).getChannel(); 
       dst.transferFrom(src, 0, src.size()); 
       src.close(); 
       dst.close(); 
      } 
     } 
     Toast.makeText(applicationContext, "Save completed !!.", Toast.LENGTH_SHORT).show(); 
    } catch (Exception e) { 
     e.printStackTrace(); 
    } 
} 

:

여기 내 코드입니다. 어떻게 고칠 수 있니?

Answer 1

Ship an application with a database

public class PlanDetailsSQLiteOpenHelper extends SQLiteOpenHelper { 
private static final String TAG = "SQLiteOpenHelper"; 

private final Context context; 
private static final int DATABASE_VERSION = 1; 
private static final String DATABASE_NAME = "my_custom_db"; 

private boolean createDb = false, upgradeDb = false; 

public PlanDetailsSQLiteOpenHelper(Context context) { 
    super(context, DATABASE_NAME, null, DATABASE_VERSION); 
    this.context = context; 
} 

/** 
* Copy packaged database from assets folder to the database created in the 
* application package context. 
* 
* @param db 
*   The target database in the application package context. 
*/ 
private void copyDatabaseFromAssets(SQLiteDatabase db) { 
    Log.i(TAG, "copyDatabase"); 
    InputStream myInput = null; 
    OutputStream myOutput = null; 
    try { 
     // Open db packaged as asset as the input stream 
     myInput = context.getAssets().open("path/to/shipped/db/file"); 

     // Open the db in the application package context: 
     myOutput = new FileOutputStream(db.getPath()); 

     // Transfer db file contents: 
     byte[] buffer = new byte[1024]; 
     int length; 
     while ((length = myInput.read(buffer)) > 0) { 
      myOutput.write(buffer, 0, length); 
     } 
     myOutput.flush(); 

     // Set the version of the copied database to the current 
     // version: 
     SQLiteDatabase copiedDb = context.openOrCreateDatabase(
      DATABASE_NAME, 0, null); 
     copiedDb.execSQL("PRAGMA user_version = " + DATABASE_VERSION); 
     copiedDb.close(); 

    } catch (IOException e) { 
     e.printStackTrace(); 
     throw new Error(TAG + " Error copying database"); 
    } finally { 
     // Close the streams 
     try { 
      if (myOutput != null) { 
       myOutput.close(); 
      } 
      if (myInput != null) { 
       myInput.close(); 
      } 
     } catch (IOException e) { 
      e.printStackTrace(); 
      throw new Error(TAG + " Error closing streams"); 
     } 
    } 
} 

@Override 
public void onCreate(SQLiteDatabase db) { 
    Log.i(TAG, "onCreate db"); 
    createDb = true; 
} 

@Override 
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { 
    Log.i(TAG, "onUpgrade db"); 
    upgradeDb = true; 
} 

@Override 
public void onOpen(SQLiteDatabase db) { 
    Log.i(TAG, "onOpen db"); 
    if (createDb) {// The db in the application package 
     // context is being created. 
     // So copy the contents from the db 
     // file packaged in the assets 
     // folder: 
     createDb = false; 
     copyDatabaseFromAssets(db); 

    } 
    if (upgradeDb) {// The db in the application package 
     // context is being upgraded from a lower to a higher version. 
     upgradeDb = false; 
     // Your db upgrade logic here: 
    } 
} 
}