在手機上存儲數據？

Question

我是Android應用程序新手 - 我想知道，如果我們必須創建一個應用程序，例如：使用GPS和相機API標識星星。

如何以及在哪裏可以存儲所有數據庫？正如我認爲如果我們將它們存儲在電話中，它會太小，對不起，這可能聽起來很愚蠢，但我是關於構建移動開發的新手段。

任何想法？就Camera API而言 - 我可以在哪裏找到這些信息，以便我將相機指向天空中的特定星形，例如，星形x稱爲y。我知道我們必須使用GPS座標和相機API？確定這些以便我們可以得到準確的信息。

任何人都可以幫助我解決這些問題，或者我可以從哪裏獲得有關這些信息的信息？

非常感謝， theBorneo

Answer 1

有上Data Storage一個非常好的指導。我認爲你可以找到你正在尋找的答案。

Answer 2

回答你的問題的第一部分，在Android中，我們通常使用SQLite，並且在互聯網上有很多例子，例如this之一。我特別不喜歡大多數的在線的例子，但一的基礎基本上是：

public class DataBaseHelper extends SQLiteOpenHelper { 

    private static String DB_PATH = "/data/data/com.your.application/databases/"; 

    private static String DB_NAME = "android.db"; 

    private SQLiteDatabase myDataBase; 

    private final Context myContext; 

    /** 
    * Constructor Takes and keeps a reference of the passed context in order to 
    * access to the application assets and resources. 
    * 
    * @param context 
    */ 
    public DataBaseHelper(Context context) { 

     super(context, DB_NAME, null, 1); 
     this.myContext = context; 
    } 

    /** 
    * Creates a empty database on the system and rewrites it with your own 
    * database. 
    */ 
    public void createDataBase() throws IOException { 

     boolean dbExist = checkDataBase(); 

     if (dbExist) { 
      // do nothing - database already exist 
      Log.v("Database","Database Exists"); 
     } else { 
      Log.v("Database","Data base needs creating"); 
      // By calling this method and empty database will be created into 
      // the default system path 
      // of your application so we are gonna be able to overwrite that 
      // database with our database. 
      this.getReadableDatabase(); 

      try { 

       Log.v("Database","CopyDataBase"); 
       copyDataBase(); 

      } catch (IOException e) { 

       throw new Error("Error Copying Database"); 

      } 
     } 

    } 

    /** 
    * Check if the database already exist to avoid re-copying the file each 
    * time you open the application. 
    * 
    * @return true if it exists, false if it doesn't 
    */ 
    private boolean checkDataBase() { 

     SQLiteDatabase checkDB = null; 

     try { 
      String myPath = DB_PATH + DB_NAME; 
      checkDB = SQLiteDatabase.openDatabase(myPath, null, 
        SQLiteDatabase.OPEN_READWRITE); 

     } catch (SQLiteException e) { 

      // database does't exist yet. 

     } 

     if (checkDB != null) { 

      checkDB.close(); 

     } 

     return checkDB != null ? true : false; 
    } 

    /** 
    * Copies your database from your local assets-folder to the just created 
    * empty database in the system folder, from where it can be accessed and 
    * handled. This is done by transfering bytestream. 
    */ 
    private void copyDataBase() throws IOException { 

     // Open your local db as the input stream 
     InputStream myInput = myContext.getAssets().open(DB_NAME); 

     // Path to the just created empty db 
     String outFileName = DB_PATH + DB_NAME; 

     // Open the empty db as the output stream 
     OutputStream myOutput = new FileOutputStream(outFileName); 

     // transfer bytes from the inputfile to the outputfile 
     byte[] buffer = new byte[1024]; 
     int length; 
     while ((length = myInput.read(buffer)) > 0) { 
      myOutput.write(buffer, 0, length); 
     } 

     // Close the streams 
     myOutput.flush(); 
     myOutput.close(); 
     myInput.close(); 

     Log.v("Log","Database copied sucsessfully"); 
    } 

    public void openDataBase() throws SQLException { 

     // Open the database 
     String myPath = DB_PATH + DB_NAME; 
     myDataBase = SQLiteDatabase.openDatabase(myPath, null,SQLiteDatabase.OPEN_READWRITE); 

     Log.v("Logger","Database Opened"); 

    } 

    @Override 
    public synchronized void close() { 

     if (myDataBase != null) 
      myDataBase.close(); 

     super.close(); 

    } 

    @Override 
    public void onCreate(SQLiteDatabase db) { 

    } 

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

    } 

    public Cursor get() { 
     return myDataBase.query("AwayMessages", null, null, null, null, null,null); 
    } 

    public SQLiteDatabase returnDatabase() { 
     return myDataBase; 
    } 

} 

隨着該SQLite數據庫將時間提前準備，前啓動應用程序，並保存在假設資產文件夾

至於GPS，嘗試here

然後，啓動攝像頭和得到的圖片回來到應用程序中，檢查出this question