Question

我正在尝试在我的Android应用程序中DL .sqlite文件，存储它然后使用它。如果我理解正确，我首先需要从URL中对数据库进行DL，将其放在assets文件夹中，然后将其复制到：＆＃34; / data / data / {package_name} / databases /＆＃34;夹。我找到了这个答案，帮助我从资产目录中复制数据库，但我仍然无法首先下载数据库。 Simple export and import of a SQLite database on Android

我在android dev中相当新，如果有人知道一步一步的教程或开源应用程序这样做会非常棒。

Answer 1

要手动创建数据库，请使用Contract Android类。使用SQLiteBrowser在Android Studio中使用Monitor下载.sqlite文件以获取数据。

Answer 2

首先：在app / assets中创建一个名称为 assets 的文件夹然后：将 db.sqlite 复制到文件夹资产

创建SqliteHelper.class

public class SqliteHelper扩展了SQLiteOpenHelper {

public static String DB_PATH = "/data/data/package.your.name/databases/";
private static String DB_NAME = "your_name_db.sqlite";
private final Context context;

public SqliteHelper(Context context) {
    super(context, DB_NAME, null, 1);
    this.context = context;
}

/**
 * copy database from assets to the device if not existed
**/
public boolean isCreatedDatabase() throws IOException {
    // Default là đã có DB
    boolean result = true;
    // Nếu chưa tồn tại DB thì copy từ Asses vào Data
    if (!checkExistDataBase()) {
         this.getReadableDatabase();
        try {
            copyDataBase();
            result = false;
        } catch (Exception e) {
            throw new Error("Error copying database");
        }
        // nó chưa tồn tại thì file sharedpreferences cũng chưa tồn tại tạo luôn
        //isCreateSP();
    }
    return result;
}


/**
 * check database exist on the device?
 */
private boolean checkExistDataBase() {

    try {
        String myPath = DB_PATH + DB_NAME;
        File fileDB = new File(myPath);
        if (fileDB.exists()) {
            return true;
        } else
            return false;
    } catch (Exception e) {
        return false;
    }
}

/**
 * copy database from assets folder to the device
 * 
 * @throws IOException
 */
private void copyDataBase() throws IOException {
    InputStream myInput = context.getAssets().open(DB_NAME);
    OutputStream myOutput = new FileOutputStream(DB_PATH + DB_NAME);
    byte[] buffer = new byte[1024];
    int length;
    while ((length = myInput.read(buffer)) > 0) {
        myOutput.write(buffer, 0, length);
    }
    myOutput.flush();
    myOutput.close();
    myInput.close();
}

@Override
public void onCreate(SQLiteDatabase db) {
    // TODO Auto-generated method stub

}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    // TODO Auto-generated method stub

}
}

在MainActivity.class中，创建方法isCreateDB：“将数据从资产复制到data / data /....”

公共类MainActivity扩展了Activity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_test);

    isCreateDB();
}

    /*
 * Copy db from asset vào database
 */
private boolean isCreateDB() {
    SqliteHelper data = new SqliteHelper(this);
    try {

        return data.isCreatedDatabase();

    } catch (IOException e) {
        Toast.makeText(this, "Error copying database", Toast.LENGTH_LONG).show();
        e.printStackTrace();
        return false;
    }
}

下载sqlite文件并在我的Android应用程序中使用它

2 个答案: