程序内使用SQLite数据库是通过SQLiteOpenHelper进行操作
1. 自己写个类继承SQLiteOpenHelper,重写以下3个方法
public void onCreate(SQLiteDatabase db)
{//创建数据库时的操作,如建表}
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion)
{
//版本更新的操作
}
2. 通过SQLiteOpenHelper的getWritableDatabase()获得一个SQLiteDatabase数据库,以后的操作都是对SQLiteDatabase进行操作。
3. 对得到的SQLiteDatabase对象进行增,改,删,查等操作。
代码
package cx.myNote;
import android.content.ContentValues; import android.content.Context; import android.content.Intent; import android.database.Cursor; import android.database.sqlite.SQLiteDatabase; import android.database.sqlite.SQLiteOpenHelper;
//DBOptions for login public class DBOptions { private static final String DB_NAME = "notes.db"; private static final String DB_CREATE="create table logininf(name text,pwd text)"; public class DBHelper extends SQLiteOpenHelper {
public DBHelper(Context context) { super(context,DB_NAME, null, 1); }
@Override public void onCreate(SQLiteDatabase db) { // TODO Auto-generated method stub //建表 db.execSQL(DB_CREATE); }
@Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { // TODO Auto-generated method stub db.execSQL("drop table if exists logininf"); onCreate(db); }
} private Context context; private SQLiteDatabase db; private DBHelper dbHelper; public DBOptions(Context context) { this.context = context; dbHelper = new DBHelper(context); db=dbHelper.getReadableDatabase();
} //自己写的方法,对数据库进行操作 public String getName() {
Cursor cursor = db.rawQuery("select name from logininf", null); cursor.moveToFirst(); return cursor.getString(0); } public int changePWD(String oldP,String pwd) { ContentValues values = new ContentValues(); values.put("pwd", pwd); return db.update("logininf", values,"pwd="+oldP, null); } } |