如何將我的數據庫打包到我的應用程序中？

Question

我有一個SQLite數據庫，在我的應用程序中是必需的。當我在模擬器上的PC上運行它時，它的工作原理完美無瑕。當我在手機上運行它時，它會崩潰，因爲該方法無法連接到數據庫，因此返回null。

這是我已經把我的數據庫做準備。但我不確定我是如何將它與我的應用程序打包在一起的。

這裏是我的DatabaseHandler.java：

package com.example.brad.myapplication; 

import android.accounts.Account; 
import android.database.DatabaseUtils; 
import android.content.ContentValues; 
import android.content.Context; 
import android.database.Cursor; 
import android.database.sqlite.SQLiteDatabase; 
import android.database.sqlite.SQLiteOpenHelper; 
import android.net.Uri; 

import static android.database.DatabaseUtils.dumpCursorToString; 

/** 
* Created by Brad on 19/07/2014. 
*/ 
public class DatabaseHandler extends SQLiteOpenHelper { 

    private static final int DATABASE_VERSION = 1; 
    private static final String DATABASE_NAME = "carsGrid", 
    TABLE_CARS = "cars ", 
    KEY_ID = "id", 
    KEY_POSTCODE = "postcode", 
    KEY_ADDRESS = "address", 
    KEY_IMAGE = "image"; 

    public DatabaseHandler(Context context) { 
     super(context, DATABASE_NAME, null, DATABASE_VERSION); 
    } 

    @Override 
    public void onCreate(SQLiteDatabase db) { 
     db.execSQL("CREATE TABLE " + TABLE_CARS + "(" + KEY_ID + " INTEGER PRIMARY KEY AUTOINCREMENT," + KEY_ADDRESS + " TEXT,"+ KEY_POSTCODE + " TEXT," + KEY_IMAGE + " TEXT)"); 
    } 

    @Override 
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { 
     db.execSQL("DROP TABLE IF EXISTS " + TABLE_CARS); 

     onCreate(db); 
    } 

    public void createCar(Car car) { 
     SQLiteDatabase db = getWritableDatabase(); 

     ContentValues values = new ContentValues(); 

     values.put(KEY_ADDRESS, car.get_address()); 
     values.put(KEY_POSTCODE, car.get_postcode()); 
     values.put(KEY_IMAGE, car.get_image()); 

     db.insert(TABLE_CARS, null, values); 
     db.close(); 
    } 

    public Car getCar(int id) { 
     SQLiteDatabase db = getReadableDatabase(); 

     Cursor cursor = db.query(TABLE_CARS, new String[] {KEY_ID, KEY_IMAGE, KEY_ADDRESS, KEY_POSTCODE}, KEY_ID + "=?", new String[] { String.valueOf(id)}, null,null,null,null); 

     if (cursor != null) 
      cursor.moveToFirst(); 

     Car car = new Car(Integer.parseInt(cursor.getString(0)), cursor.getString(1), cursor.getString(2),cursor.getString(3)); 
     return car; 
    } 

    public int getCarCount() { 
     //SELECT * FROM CARS 
     SQLiteDatabase db = getReadableDatabase(); 
     Cursor cursor = db.rawQuery("SELECT * FROM " + TABLE_CARS, null); 
     cursor.close(); 

     return cursor.getCount(); 
    } 

    public String getRandomImageKey() { 
     //SELECT * FROM CARS 
     SQLiteDatabase db = getReadableDatabase(); 
     Cursor cursor = db.rawQuery("SELECT " + KEY_ID + "," + KEY_IMAGE + " FROM " + TABLE_CARS + " ORDER BY RANDOM() LIMIT 1", null); 
     int columnIndex = cursor.getColumnIndex(KEY_ID); 
     String toReturn = cursor.getString(columnIndex); 
     return toReturn; 
    } 

    public Car getCurrentCar() { 

     SQLiteDatabase db  = getWritableDatabase(); 
     String sql    = "SELECT " + KEY_ID + "," + KEY_ADDRESS + "," + KEY_POSTCODE + "," + KEY_IMAGE + " FROM " + TABLE_CARS + " ORDER BY RANDOM() LIMIT 1"; 
     Cursor cursor   = db.rawQuery(sql, new String[] {}); 
     Car car = null; 

     try { 
      if (cursor.moveToFirst()) { 
       car = new Car(Integer.parseInt(cursor.getString(0)), cursor.getString(1), cursor.getString(2), cursor.getString(3)); 
      } 
     } 
     finally { 
      if (cursor != null && !cursor.isClosed()) { 
       cursor.close(); 
      } 
       db.close(); 
     } 
     return car; 
    } 
} 

Answer 1

如何我打包我的數據庫在我的應用程序？

Use SQLiteAssetHelper在您的應用第一次運行時從資產解壓縮數據庫。