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我正在尝试制作我的第一个真正的应用程序，它会在一秒钟内变成地狱。首先，我试图通过制作一些教程来理解架构，但是不同的教程对数据库的说法不同，我有点困惑。我想向您说明我的实际位置：

我的数据库助手：

public class MySQLiteHelper extends SQLiteOpenHelper {

  public static final String TABLE_CATEGORIE = "categorie";
  public static final String TABLE_SONDAGGI = "sondaggi";
  public static final String TABLE_TESTORISPOSTE = "testo_risposte";
  public static final String TABLE_RISPOSTE = "risposte";    
  public static final String COLUMN_ID = "_id";
  public static final String COLUMN_NOME = "nome";
  public static final String COLUMN_PREF = "preferita"; 
  public static final String COLUMN_CATID = "catid";
  public static final String COLUMN_DOMANDA = "domanda";
  public static final String COLUMN_SONDID = "sondid";
  public static final String COLUMN_RISPOSTA = "risposta";
  public static final String COLUMN_RISID = "risid";
  public static final String COLUMN_SELEZIONATA = "selezionata";


  private static final String DATABASE_NAME = "democracy.db";
  private static final int DATABASE_VERSION = 2;

  // Database creation sql statement


  private static final String DATABASE_CREATE_CATEGORIE = "create table "
      + TABLE_CATEGORIE + "(" + COLUMN_ID
      + " integer primary key autoincrement, " + COLUMN_PREF
      + " integer null, " + COLUMN_NOME
      + " text not null);";

  private static final String DATABASE_CREATE_SONDAGGI = "create table "
          + TABLE_SONDAGGI + "(" + COLUMN_ID
          + " integer primary key autoincrement, " + COLUMN_CATID
          + " integer not null, "+ COLUMN_DOMANDA +" text not null);";


  private static final String DATABASE_CREATE_TESTORISPOSTE = "create table "
          + TABLE_TESTORISPOSTE + "(" + COLUMN_ID
          + " integer primary key autoincrement, " + COLUMN_SONDID
          + " integer not null, "+ COLUMN_SELEZIONATA
          + " integer, "+ COLUMN_RISPOSTA +" text not null);";


  public MySQLiteHelper(Context context) {
    super(context, DATABASE_NAME, null, DATABASE_VERSION);
  }

  @Override
  public void onCreate(SQLiteDatabase database) {
    database.execSQL(DATABASE_CREATE_CATEGORIE);
    database.execSQL(DATABASE_CREATE_SONDAGGI);
    database.execSQL(DATABASE_CREATE_TESTORISPOSTE);


  }

  @Override
  public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    Log.w(MySQLiteHelper.class.getName(),
        "Upgrading database from version " + oldVersion + " to "
            + newVersion + ", which will destroy all old data");
    db.execSQL("DROP TABLE IF EXISTS " + TABLE_CATEGORIE);
    db.execSQL("DROP TABLE IF EXISTS " + TABLE_SONDAGGI);
    db.execSQL("DROP TABLE IF EXISTS " + TABLE_TESTORISPOSTE);



    onCreate(db);
  }

}

我得到的表类之一：

public class categorie {
      private long id;
      private String nome;
      private long preferita;

      public long getId() {
        return id;
      }

      public void setId(long id) {
        this.id = id;
      }

      public String getNome() {
        return nome;
      }

      public void setNome(String nome) {
        this.nome = nome;
      }



      public long getPreferita() {
        return preferita;
    }

    public void setPreferita(long preferita) {
        this.preferita = preferita;
    }

    // Will be used by the ArrayAdapter in the ListView
      @Override
      public String toString() {
        return nome;
      }
    }

数据源：

public class pollDataSource {
    // Database fields
      private SQLiteDatabase database;
      private MySQLiteHelper dbHelper;
      private String[] allCategorieColumns = { MySQLiteHelper.COLUMN_ID,
          MySQLiteHelper.COLUMN_PREF, MySQLiteHelper.COLUMN_NOME };   
      private String[] allSondaggiColumns = { MySQLiteHelper.COLUMN_ID,
              MySQLiteHelper.COLUMN_CATID, MySQLiteHelper.COLUMN_DOMANDA };   
      private String[] allRisposteColumns = { MySQLiteHelper.COLUMN_ID, 
              MySQLiteHelper.COLUMN_SONDID, MySQLiteHelper.COLUMN_RISPOSTA, 
              MySQLiteHelper.COLUMN_SELEZIONATA };


      public pollDataSource(Context context) {
            dbHelper = new MySQLiteHelper(context);
          }

      public void open() throws SQLException {
            database = dbHelper.getWritableDatabase();
          }

      public void close() {
            dbHelper.close();
          }

      public categorie createCategoria(String categoria) {
            ContentValues values = new ContentValues();
            values.put(MySQLiteHelper.COLUMN_NOME, categoria);
            values.put(MySQLiteHelper.COLUMN_PREF, 0);
            long insertId = database.insert(MySQLiteHelper.TABLE_CATEGORIE, null,
                values);
            Cursor cursor = database.query(MySQLiteHelper.TABLE_CATEGORIE,
                allCategorieColumns, MySQLiteHelper.COLUMN_ID + " = " + insertId, null,
                null, null, null);
            cursor.moveToFirst();
            categorie newCategoria = cursorToCategorie(cursor);
            cursor.close();
            return newCategoria;
          } 

      public void deleteCategoria(categorie categoria) {
            long id = categoria.getId();
            System.out.println("Categoria cancellata, id: " + id);
            database.delete(MySQLiteHelper.TABLE_CATEGORIE, MySQLiteHelper.COLUMN_ID
                + " = " + id, null);
          }

      public sondaggi createSondaggio(String domanda, int catid) {
            ContentValues values = new ContentValues();
            values.put(MySQLiteHelper.COLUMN_DOMANDA, domanda);
            values.put(MySQLiteHelper.COLUMN_CATID, catid);
            long insertId = database.insert(MySQLiteHelper.TABLE_SONDAGGI, null,
                values);
            Cursor cursor = database.query(MySQLiteHelper.TABLE_SONDAGGI,
                allSondaggiColumns, MySQLiteHelper.COLUMN_ID + " = " + insertId, null,
                null, null, null);
            cursor.moveToFirst();
            sondaggi newSondaggio = cursorToSondaggi(cursor);
            cursor.close();
            return newSondaggio;
          }


      public void deleteSondaggio(sondaggi sondaggio) {
            long id = sondaggio.getId();
            System.out.println("Sondaggio cancellato, id: " + id);
            database.delete(MySQLiteHelper.TABLE_SONDAGGI, MySQLiteHelper.COLUMN_ID
                + " = " + id, null);
          } 

      public Cursor getAllCategorie() {
            List<categorie> categorie = new ArrayList<categorie>();

            Cursor cursor = database.query(MySQLiteHelper.TABLE_CATEGORIE,
                allCategorieColumns, null, null, null, null, null);

            cursor.moveToFirst();
            while (!cursor.isAfterLast()) {
              categorie categoria = cursorToCategorie(cursor);
              categorie.add(categoria);
              cursor.moveToNext();
            }
            // Make sure to close the cursor
           // cursor.close();
            return cursor;
          }


      private categorie cursorToCategorie(Cursor cursor) {
          categorie categorie = new categorie();
          categorie.setId(cursor.getLong(0));
          categorie.setPreferita(cursor.getLong(1));
          categorie.setNome(cursor.getString(2));
            return categorie;
          }
      private sondaggi cursorToSondaggi(Cursor cursor) {
          sondaggi sondaggi = new sondaggi();
          sondaggi.setId(cursor.getLong(0));
          sondaggi.setDomanda(cursor.getString(1));
          sondaggi.setCatid(cursor.getLong(2));
          return sondaggi;
          }


}

最后，主要活动：

public class MainActivity extends ListActivity {
     private pollDataSource datasource;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        datasource = new pollDataSource(this);
        datasource.open();

        Cursor values = datasource.getAllCategorie();

        String[] categorieColumns =
            {
                MySQLiteHelper.COLUMN_NOME   // Contract class constant containing the word column name

            };


            int[] mWordListItems = { R.id.categoria_label };


        SimpleCursorAdapter adapter = new SimpleCursorAdapter(
                getApplicationContext(),               // The application's Context object
                R.layout.single_list_item,             // A layout in XML for one row in the ListView
                values,                                // The result from the query
                categorieColumns,                      // A string array of column names in the cursor
                mWordListItems,                        // An integer array of view IDs in the row layout
                0);                                    // Flags (usually none are needed)

    // Sets the adapter for the ListView
        setListAdapter(adapter);
    }


       // Will be called via the onClick attribute
      // of the buttons in main.xml

      public void onClick(View view) {

        switch (view.getId()) {
        case R.id.add:


          break;

        }

      }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }



}

我实际上是在尝试了解在何处以及如何添加方法以将内容添加到我的类别表中...我想我应该创建一个“插入”方法，或者我不得不调用类别类并使用 setNome .. .但我真的很困惑......谁能指出我正确的方向？

4

2 回答 2

2

你可以用很多不同的方式做到这一点。这是一个：

助手类：

 new Database(getWriteableDatabase()).save(someCategorie);

SQL 常量：

public static final String TABLE_NAME = "Categorie"

public static final String SAVE = "INSERT INTO "+ TABLE_NAME +
            " VALUES (NULL, ?, ?);";

数据库类：

public Database(SQLiteDatabase database) {
        this.database = database;
    }

public void save(Categorie categorie) {
        SQLiteStatement statement = database.compileStatement(SAVE);

        statement.bindString(1, categorie.getSomething());
        statement.bindLong(2, categorie.getSomethingElse());

        statement.execute();

        statement.close();
    }

这是另一个：

使用库https://github.com/novoda/SQLiteProvider

于 2012-12-19T11:56:04.097 回答
1

这些是帮助我学习的教程，但您可能需要返回一两个视频。本质上，您可以将要插入的值添加到内容值中，这些值将类别名称作为第一个参数，将值作为第二个参数。

于 2012-12-19T12:05:15.857 回答