在Android中,处理数据库操作通常使用SQLite数据库。SQLite是一个轻量级、可嵌入式的数据库引擎,适用于Android移动设备。要在Android中实现数据库操作,请遵循以下步骤:
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创建数据库帮助类: 首先,创建一个名为DatabaseHelper的类,该类继承自SQLiteOpenHelper。这个类将负责创建和管理数据库。
import android.content.Context; import android.database.sqlite.SQLiteDatabase; import android.database.sqlite.SQLiteOpenHelper; public class DatabaseHelper extends SQLiteOpenHelper { private static final String DATABASE_NAME = "myDatabase.db"; private static final int DATABASE_VERSION = 1; public static final String TABLE_NAME = "myTable"; public static final String COLUMN_ID = "_id"; public static final String COLUMN_NAME = "name"; private static final String CREATE_TABLE = "CREATE TABLE " + TABLE_NAME + " (" + COLUMN_ID + " INTEGER PRIMARY KEY AUTOINCREMENT, " + COLUMN_NAME + " TEXT)"; public DatabaseHelper(Context context) { super(context, DATABASE_NAME, null, DATABASE_VERSION); } @Override public void onCreate(SQLiteDatabase db) { db.execSQL(CREATE_TABLE); } @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { db.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME); onCreate(db); } }
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在Activity中使用数据库帮助类: 在你的Activity中,实例化DatabaseHelper类,并使用它来执行数据库操作,如插入、查询、更新和删除。
import android.database.Cursor; import android.os.Bundle; import android.widget.TextView; import androidx.appcompat.app.AppCompatActivity; public class MainActivity extends AppCompatActivity { private DatabaseHelper dbHelper; private TextView textView; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); textView = findViewById(R.id.textView); dbHelper = new DatabaseHelper(this); // 插入数据 insertData(); // 查询数据 queryData(); } private void insertData() { SQLiteDatabase db = dbHelper.getWritableDatabase(); String name = "John Doe"; db.insert(DatabaseHelper.TABLE_NAME, null, DatabaseHelper.createValueList(DatabaseHelper.COLUMN_NAME, name)); db.close(); } private void queryData() { SQLiteDatabase db = dbHelper.getReadableDatabase(); Cursor cursor = db.rawQuery("SELECT * FROM " + DatabaseHelper.TABLE_NAME, null); if (cursor.moveToFirst()) { do { int id = cursor.getInt(cursor.getColumnIndex(DatabaseHelper.COLUMN_ID)); String name = cursor.getString(cursor.getColumnIndex(DatabaseHelper.COLUMN_NAME)); textView.setText("ID: " + id + ", Name: " + name); } while (cursor.moveToNext()); } cursor.close(); db.close(); } }
这个示例展示了如何在Android中创建一个SQLite数据库,并向其中插入和查询数据。你可以根据需要扩展这个示例,以实现更新和删除操作。