创建数据库以及dao方法使用

public class NewsSqliteOpenHelper extends SQLiteOpenHelper {

    public NewsSqliteOpenHelper(@Nullable Context context) {
        super(context, "news.db", null, 1);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL("create table news(_id INTEGER primary key autoincrement, url TEXT, json TEXT)");
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

    }
 

 

 

 

 

 

 

 

 

public class NewDao  {

  private NewsSqliteOpenHelper helper;
  private SQLiteDatabase db;

  public NewDao(Context context){
        helper = new NewsSqliteOpenHelper(context);
        db=helper.getWritableDatabase();
  }

  public void replace(NewsBean bean){

      ContentValues values = new ContentValues();
      values.put("url",bean.url);
      values.put("json",bean.json);

      db.replace("news",null,values);
  }
    /**
     * 查询
     *
     * @param url
     * @return
     */
    public NewsBean load(String url) {
        NewsBean newsBean = null;
        Cursor cursor = db.rawQuery("select * from news where url = ?", new String[]{url});
        if (cursor.moveToNext()) {
            newsBean = new NewsBean();
            newsBean.url = cursor.getString(cursor.getColumnIndex("url"));
            newsBean.json = cursor.getString(cursor.getColumnIndex("json"));
        }
        return newsBean;
    }

}