Android SQLite,JSON,List 用于存储常量对象
创始人
2024-08-15 20:30:10
0

要实现将常量对象存储在Android SQLite数据库中,并以JSON格式存储在List中,可以按照以下步骤进行:

  1. 创建一个常量对象类,包含常量的属性和方法。例如,假设我们要存储一个名为Constant的常量对象,它具有id、name和value属性,可以定义如下:
public class Constant {
    private int id;
    private String name;
    private String value;

    // 构造函数和getter/setter方法省略
}
  1. 创建一个SQLiteOpenHelper子类,用于创建和管理SQLite数据库。例如,假设我们创建一个名为ConstantDatabaseHelper的类,可以定义如下:
public class ConstantDatabaseHelper extends SQLiteOpenHelper {
    private static final String DATABASE_NAME = "constants.db";
    private static final int DATABASE_VERSION = 1;

    private static final String TABLE_NAME = "constants";
    private static final String COLUMN_ID = "id";
    private static final String COLUMN_NAME = "name";
    private static final String COLUMN_VALUE = "value";

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

    @Override
    public void onCreate(SQLiteDatabase db) {
        String createTableQuery = "CREATE TABLE " + TABLE_NAME + " (" +
                COLUMN_ID + " INTEGER PRIMARY KEY AUTOINCREMENT, " +
                COLUMN_NAME + " TEXT, " +
                COLUMN_VALUE + " TEXT)";
        db.execSQL(createTableQuery);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        db.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME);
        onCreate(db);
    }
}
  1. 创建一个数据访问对象(DAO)类,用于执行数据库操作。例如,假设我们创建一个名为ConstantDAO的类,可以定义如下:
public class ConstantDAO {
    private SQLiteDatabase database;
    private ConstantDatabaseHelper dbHelper;

    public ConstantDAO(Context context) {
        dbHelper = new ConstantDatabaseHelper(context);
    }

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

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

    public void insert(Constant constant) {
        ContentValues values = new ContentValues();
        values.put(ConstantDatabaseHelper.COLUMN_NAME, constant.getName());
        values.put(ConstantDatabaseHelper.COLUMN_VALUE, constant.getValue());
        database.insert(ConstantDatabaseHelper.TABLE_NAME, null, values);
    }

    public List getAllConstants() {
        List constants = new ArrayList<>();
        Cursor cursor = database.query(ConstantDatabaseHelper.TABLE_NAME, null, null, null, null, null, null);
        cursor.moveToFirst();
        while (!cursor.isAfterLast()) {
            Constant constant = new Constant();
            constant.setId(cursor.getInt(cursor.getColumnIndex(ConstantDatabaseHelper.COLUMN_ID)));
            constant.setName(cursor.getString(cursor.getColumnIndex(ConstantDatabaseHelper.COLUMN_NAME)));
            constant.setValue(cursor.getString(cursor.getColumnIndex(ConstantDatabaseHelper.COLUMN_VALUE)));
            constants.add(constant);
            cursor.moveToNext();
        }
        cursor.close();
        return constants;
    }
}
  1. 在需要存储常量对象的地方,可以按照以下方式使用ConstantDAO类:
// 创建ConstantDAO对象
ConstantDAO constantDAO = new ConstantDAO(context);

// 打开数据库连接
constantDAO.open();

// 创建常量对象
Constant constant1 = new Constant();
constant1.setName("Constant1");
constant1.setValue("Value1");

// 插入常量对象到数据库
constantDAO.insert(constant1);

// 获取所有常量对象
List constants = constantDAO.getAllConstants();

// 关闭数据库连接
constantDAO.close();

通过以上步骤,我们可以将常量对象存储在Android SQLite数据库中,并以JSON格式存储在List中。

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