public class ShoppingDBHelper extends SQLiteOpenHelper {
    private static final String DB_NAME = "shopping.db";
    private static final String TABLE_GOODS_INFO = "goods_info";
    private static final String TABLE_CART_INFO = "cart_info";
    private static final int DB_VERSION = 1;

    private static ShoppingDBHelper mHelper = null;
    private SQLiteDatabase mRDB = null;
    private SQLiteDatabase mWDB = null;


    private ShoppingDBHelper(Context context) {
        super(context, DB_NAME, null, DB_VERSION);
    }

    public static ShoppingDBHelper getInstance(Context context) {
        if (mHelper == null) {
            mHelper = new ShoppingDBHelper(context);

        }
        return mHelper;

    }

    public SQLiteDatabase openReadLink() {
        if (mRDB == null || !mRDB.isOpen()) {
            mRDB = mHelper.getReadableDatabase();

        }
        return mRDB;
    }

    public SQLiteDatabase openWriteLink() {
        if (mWDB == null || !mWDB.isOpen()) {
            mWDB = mHelper.getWritableDatabase();
        }
        return mWDB;
    }

    public void closeLink() {
        if (mRDB != null && mRDB.isOpen()) {
            mRDB.close();
            mRDB = null;
        }
        if (mWDB != null && mWDB.isOpen()) {
            mWDB.close();
            mWDB = null;
        }

    }


    @Override
    public void onCreate(SQLiteDatabase db) {
        String sql = "CREATE TABLE IF NOT EXISTS " + TABLE_GOODS_INFO + " (" +
                "_id INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL," +
                " name VARCHAR NOT NULL," +
                " description VARCHAR NOT NULL," +
                " price FLOAT NOT NULL," +
                " pic_path VARCHAR NOT NULL);";
        db.execSQL(sql);

        sql = "CREATE TABLE IF NOT EXISTS " + TABLE_CART_INFO + " (" +
                "_id INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL," +
                " goods_id INTEGER NOT NULL," +
                " count INTEGER NOT NULL);";

        db.execSQL(sql);
    }

    @Override
    public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {


    }
}

public class GoodsInfo {

    public int id;
    // 名称
    public String name;
    // 描述
    public String description;
    // 价格
    public float price;
    // 大图的保存路径
    public String picPath;
    // 大图的资源编号
    public int pic;

    // 声明一个手机商品的名称数组
    private static String[] mNameArray = {
            "iPhone11", "Mate30", "小米10", "OPPO Reno3", "vivo X30", "荣耀30S"
    };
    // 声明一个手机商品的描述数组
    private static String[] mDescArray = {
            "Apple iPhone11 256GB 绿色 4G全网通手机",
            "华为 HUAWEI Mate30 8GB+256GB 丹霞橙 5G全网通 全面屏手机",
            "小米 MI10 8GB+128GB 钛银黑 5G手机 游戏拍照手机",
            "OPPO Reno3 8GB+128GB 蓝色星夜 双模5G 拍照游戏智能手机",
            "vivo X30 8GB+128GB 绯云 5G全网通 美颜拍照手机",
            "荣耀30S 8GB+128GB 蝶羽红 5G芯片 自拍全面屏手机"
    };
    // 声明一个手机商品的价格数组
    private static float[] mPriceArray = {6299, 4999, 3999, 2999, 2998, 2399};
    // 声明一个手机商品的大图数组
    private static int[] mPicArray = {
            R.drawable.iphone, R.drawable.huawei, R.drawable.xiaomi,
            R.drawable.oppo, R.drawable.vivo, R.drawable.rongyao
    };

    // 获取默认的手机信息列表
    public static ArrayList<GoodsInfo> getDefaultList() {
        ArrayList<GoodsInfo> goodsList = new ArrayList<GoodsInfo>();
        for (int i = 0; i < mNameArray.length; i++) {
            GoodsInfo info = new GoodsInfo();
            info.id = i;
            info.name = mNameArray[i];
            info.description = mDescArray[i];
            info.price = mPriceArray[i];
            info.pic = mPicArray[i];
            goodsList.add(info);
        }
        return goodsList;
    }
}

public void insertGoodsInfos(List<GoodsInfo> list)
    {
        try {
            mWDB.beginTransaction();
            for (GoodsInfo info : list) {
                ContentValues values = new ContentValues();
                values.put("name",info.name);
                values.put("description",info.description);
                values.put("price",info.price);
                values.put("pic_path",info.picPath);
                mWDB.insert(TABLE_GOODS_INFO,null,values);
            }


            mWDB.setTransactionSuccessful();

        }catch (Exception e)
        {
            e.printStackTrace();
        }
        finally {
            mWDB.endTransaction();
        }
    }

public void onCreate() {
        super.onCreate();
        Log.d("sch", "Application onCreate");
        initGoodsInfo();
    }

private void initGoodsInfo() {
    //ShareUtill是用于操作sharedpreference的工具类

    boolean isFirst = ShareUtil.getInstance(this).readBoolean("first",true);
    //如果是第一次打开
    if (isFirst)
    {
        String directory = getExternalFilesDir(Environment.DIRECTORY_DOWNLOADS).toString() + File.separatorChar;
        List<GoodsInfo> list = GoodsInfo.getDefaultList();
        for (GoodsInfo info : list) {
            String path = directory+info.id + ".jpg";
            Bitmap bitmap = BitmapFactory.decodeResource(getResources(),info.pic);
            FileUtil.saveImage(path,bitmap);
            bitmap.recycle();
            info.picPath = path;
        }
        ShoppingDBHelper dbHelper = ShoppingDBHelper.getInstance(this);
        dbHelper.openWriteLink();
        dbHelper.insertGoodsInfos(list);
        dbHelper.closeLink();
        ShareUtil.getInstance(this).writeBoolean("first",false);
    }


}

public class ShareUtil {
    private static ShareUtil mUtil;
    private SharedPreferences preferences;
    public static ShareUtil getInstance(Context context)
    {
        if (mUtil == null)
        {
            mUtil = new ShareUtil();
            mUtil.preferences = context.getSharedPreferences("shopping",Context.MODE_PRIVATE);
        }
        return mUtil;

    }
    public boolean readBoolean(String key,boolean defaultValue)
    {
        return preferences.getBoolean(key,defaultValue);
    }
    public void writeBoolean(String key,boolean value)
    {
        SharedPreferences.Editor editor = preferences.edit();
        editor.putBoolean(key,value);
        editor.commit();
    }

}