Question

在上一篇文章中，有一种方法可以创建我的SQLiteDatabse的单个实例，然后在我的应用程序中简单地引用它。我无法弄清楚如何告诉它我的数据库在哪里。由于我的数据库被写入SDCard，因此必须有一种方法告诉它应该使用哪个数据库？以下是代码：

    public class DatabaseManager {

    private int mOpenCounter;

    private static DatabaseManager instance;
    private static SQLiteOpenHelper mDatabaseHelper;
    private SQLiteDatabase mDatabase;

    public static synchronized void initializeInstance(SQLiteOpenHelper helper) {
        if (instance == null) {
            instance = new DatabaseManager();
            mDatabaseHelper = helper;
        }
    }

    public static synchronized DatabaseManager getInstance() {
        if (instance == null) {
            throw new IllegalStateException(DatabaseManager.class.getSimpleName() +
                    " is not initialized, call initializeInstance(..) method first.");
        }

        return instance;
    }

    public synchronized SQLiteDatabase openDatabase() {
        mOpenCounter++;
        if(mOpenCounter == 1) {
            // Opening new database
            mDatabase = mDatabaseHelper.getWritableDatabase();
        }
        return mDatabase;
    }

    public synchronized void closeDatabase() {
        mOpenCounter--;
        if(mOpenCounter == 0) {
            // Closing database
            mDatabase.close();

        }
    }

}

我的实际数据库名为FooBase.db

static File directoryPath = new File(Environment.getExternalStorageDirectory().toString() + "/MyApp/database");

Answer 1

您不需要明确提及数据库的路径。

默认情况下，所有Android应用程序都将其数据库存储在该位置 /data/data/packageName/

SQLiteOpenHelper - creating database on SD card

How to store sqlite database directly on sdcard

Docs

Android SQLite数据库帮助程序实例

1 个答案: