Question

我正在使用放置在app资产文件夹中的外部sqlite数据库。我可以从这个数据库中读取数据，但我想在这个数据库中插入新的条目。我知道内部数据库使用contentvalue是如此容易，但在外部数据库中如何做到这一点？

Answer 1

首先，您需要将数据库复制到SD卡，然后使用以下类初始化数据库： -

public class DatabaseHandler extends SQLiteOpenHelper
 {


  private static String TAG = "DataBaseHelper"; // Tag just for the      LogCat window
//destination path (location) of our database on device
private  String mDBpath = "";
private  String mDBpathactual = "";

private static String DB_NAME ="DKDB.sqlite";// Database name
private SQLiteDatabase mDataBase;
private final Context mContext;


public DatabaseHandler(Context context , String db_path,String db_name,int db_ver)
{
    super(context, db_name, null, db_ver);// 1? its Database Version

    if(android.os.Build.VERSION.SDK_INT >= 17){
        mDBpath = context.getApplicationInfo().dataDir + "/databases/";
    }
    else
    {

        mDBpath = "/data/data/" + context.getPackageName() + "/databases/";
    }

    DB_NAME = db_name;

    mDBpathactual = db_path+db_name;
    this.mContext = context;

   // mDBpath = this.mContext.getDatabasePath(DB_NAME);
}

public void createDataBase() throws IOException
{
    //If database not exists copy it from the assets

    boolean mDataBaseExist = checkDataBase();
    if(!mDataBaseExist || mDataBaseExist)
    {
        this.getReadableDatabase();
        this.close();
        try
        {
            //Copy the database from assests
            copyDataBase();

            Log.e(TAG, "createDatabase database created");
        }
        catch (IOException mIOException)
        {
            throw new Error("ErrorCopyingDataBase");
        }
    }
}
//Check that the database exists here: /data/data/your package/databases/Da Name
private boolean checkDataBase()
{
    File dbFile = new File(mDBpath + DB_NAME);
    //Log.v("dbFile", dbFile + "   "+ dbFile.exists());
    if(dbFile.exists())
    dbFile.delete();
    return dbFile.exists();
}

//Copy the database from assets
private void copyDataBase() throws IOException
{

    InputStream mInput = new FileInputStream(mDBpathactual);
    String outFileName = mDBpath + DB_NAME;
    OutputStream mOutput = new FileOutputStream(outFileName);
    byte[] mBuffer = new byte[1024];
    int mLength;
    while ((mLength = mInput.read(mBuffer))>0)
    {
        mOutput.write(mBuffer, 0, mLength);
    }
    mOutput.flush();
    mOutput.close();
    mInput.close();
}

//Open the database, so we can query it
public boolean openDataBase() throws SQLException
{
    String mPath = mDBpath +DB_NAME ;
    //Log.v("mPath", mPath);
    mDataBase = SQLiteDatabase.openDatabase(mPath, null, SQLiteDatabase.CREATE_IF_NECESSARY);
    //mDataBase = SQLiteDatabase.openDatabase(mPath, null, SQLiteDatabase.NO_LOCALIZED_COLLATORS);


    return mDataBase != null;
}

@Override
public synchronized void close()
{
    if(mDataBase != null)
        mDataBase.close();
    super.close();
}

@Override
public void onCreate(SQLiteDatabase db) {

}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

}
}

如何在资产文件夹中插入外部sqlite

1 个答案: