java - 操作 SQLite 数据库中的数据

Question

我是 SQL Lite 数据库操作的新手。

我根据本教程编写了一个数据库处理类 SQL Lite tutorial

public class DatabaseHandler extends SQLiteOpenHelper {

// All Static variables
// Database Version
private static final int DATABASE_VERSION = 1;

// Database Name
private static final String DATABASE_NAME = "PersonalAssistant";

// TASKS table name
private static final String TABLE_TASKS = "TASKS";

// Tasks Table Columns names
private static final String KEY_ID = "id";
private static final String UUID = "uuid";
private static final String ACTION = "action";
private static final String TIME = "time";
private static final String DAY = "day";
private static final String RECEPIENTS = "receipients";
private static final String BODY = "body";
private static final String SUBJECT = "subject";
private static final String STATUS = "status";

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

// Creating Tables
@Override
public void onCreate(SQLiteDatabase db) {
    String CREATE_CONTACTS_TABLE = "CREATE TABLE IF NOT EXISTS " + TABLE_TASKS + "("
            + KEY_ID + " INTEGER PRIMARY KEY autoincrement," +UUID + " TEXT,"+ ACTION + " TEXT,"
            + TIME + " TEXT," + DAY + " TEXT," + RECEPIENTS+  " TEXT," +BODY + " TEXT," + " TEXT," +SUBJECT + " TEXT,"  +SUBJECT + " TEXT," +")";
    db.execSQL(CREATE_CONTACTS_TABLE);
}

// Upgrading database
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    // Drop older table if existed
    db.execSQL("DROP TABLE IF EXISTS " + TABLE_TASKS);

    // Create tables again
    onCreate(db);
}
// add task to table
public void addTask(Task task) 
{
    SQLiteDatabase db = this.getWritableDatabase();

    ContentValues values = new ContentValues();
    values.put(ACTION, task.getAction());

    values.put(UUID, task.getUuid());

    values.put(TIME, task.getTime());
    values.put(DAY, task.getDay());
    values.put(RECEPIENTS, task.getReceipients());
    values.put(BODY, task.getBody());
    values.put(SUBJECT, task.getSubject());
    values.put(STATUS, task.getStatus());

    // Inserting Row
    db.insert(TABLE_TASKS, null, values);
    db.close(); // Closing database connection
}        .............

我的问题是如何从我的应用程序 Activity 中调用此类进行数据库操作？

如何从不扩展 SQLiteOpenHelper 的其他 Activity 中实例化我的类？

我可以将类和方法定义为静态，但这是一个好的做法吗？

Answer 1

您只需从 DatabaseHandler 类实例化对象即可做到这一点，如下所示:

DabataseHandler dbHandler;
dbHandler = new DatabaseHandler(getApplicationContext());

然后您可以通过 dbHandler 使用 Databasehandler 类中的方法。

例如:

Task myTask = new Task();
dbHandler.addTask(myTask);