Android中的SQLIte来自Assets文件夹

Question

我试图从我的应用程序中的资产文件夹使用数据库，但我似乎无法引用它。

我已经得到了结构设置，如：

public static String DBName = "myDB.db"; 
public static String DBLocation = "/data/data/com.yes.auntsally/databases/"; 
public static String DBFullLocation = DBLocation + DBName; 

然后美其名曰：

public static void getDbFile() { 
     if (dbFile == null) { 
      dbFile = new File(Global.DBFullLocation); 
     } 
    } 

public static void openDb() { 
     if (db == null) { 
      getDbFile(); 
      db = SQLiteDatabase.openOrCreateDatabase(dbFile, null); 
      setDbOpen(true); 
     } 
     if (!db.isOpen()) { 
      getDbFile(); 
      db = SQLiteDatabase.openOrCreateDatabase(dbFile, null); 
      setDbOpen(true); 
     } 

    } 

，但我得到的错误：

04-02 11:51:31.375: E/SQLiteLog(4024): (14) cannot open file at line 30241 of [00bb9c9ce4] 
04-02 11:51:31.375: E/SQLiteLog(4024): (14) os_unix.c:30241: (2) open(/data/data/com.yes.auntsally/databases/myDB.db) - 
04-02 11:51:31.390: E/SQLiteDatabase(4024): Failed to open database '/data/data/com.yes.auntsally/databases/myDB.db'. 
04-02 11:51:31.390: E/SQLiteDatabase(4024): android.database.sqlite.SQLiteCantOpenDatabaseException: unknown error (code 14): Could not open database 

Answer 1

试试下面参考代码

public class DataBaseHelper extends SQLiteOpenHelper { 

private static String DB_PATH; 
private static String DB_NAME = "podcastDB.db"; 
private SQLiteDatabase myDataBase; 
private final Context myContext; 
SharedPreferences sharedPreferences; 


public DataBaseHelper(Context context) { 

    super(context, DB_NAME, null, 1); 
    this.myContext = context; 
    DB_PATH = "/data/data/" + myContext.getPackageName() + "/databases/"; 

    sharedPreferences = PreferenceManager 
      .getDefaultSharedPreferences(myContext); 
} 

/** 
* Creates a empty database on the system and rewrites it with your own 
* database. 
* */ 
public void createDataBase() throws IOException { 

    // ---Check whether database is already created or not--- 
    boolean dbExist = checkDataBase(); 

    if (dbExist) { 
    } else { 
     this.getReadableDatabase(); 
     try { 
      // ---If not created then copy the database--- 
      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() { 
    try { 
     String myPath = DB_PATH + DB_NAME; 
     File f = new File(myPath); 
     if (f.exists()) 
      return true; 
     else 
      return false; 
    } catch (SQLiteException e) { 
     Log.e("Podcast", "There was an error", e); 
     return 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 { 

    InputStream myInput = myContext.getAssets().open(DB_NAME); 

    String outFileName = DB_PATH + DB_NAME; 

    OutputStream myOutput = new FileOutputStream(outFileName); 

    byte[] buffer = new byte[1024]; 
    int length; 
    while ((length = myInput.read(buffer)) > 0) { 
     myOutput.write(buffer, 0, length); 
    } 

    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); 

} 

@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) { 

} 

Answer 2

试一下这个它非常简单库项目做了同样的

https://github.com/jgilfelt/android-sqlite-asset-helper