Android开始之 数据存储CursorAdapter游标适配器&Loader和AsyncLoader的使用

-------------PersonService-----------------------

public interface PersonService {
    public Cursor listPersonCursor();
    
    public boolean addPerson(ContentValues values);

}

-----------------------DBHelper-------------------------------------------------------

public class DBHelper extends SQLiteOpenHelper {

    private static final int VERSION = 1;// 数据库版本号
    private static final String NAME = "MYDB.DB";// 数据库名称

    public DBHelper(Context context) {
        super(context, NAME, null, VERSION);
        // TODO Auto-generated constructor stub
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        // TODO Auto-generated method stub
        //!!用SQLite数据库完成UI界面的显示，表中必须包含：_id

        String sql = "create table person(_id integer primary key autoincrement,name varchar(64),address varchar(64))";
        db.execSQL(sql);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        // TODO Auto-generated method stub

    }

}

---------------------------DBManger----------------------------------------------

public class DBManger {
    private DBHelper helper;
    private SQLiteDatabase database;
    public DBManger(Context context) {
        // TODO Auto-generated constructor stub
        helper=new DBHelper(context);
        database=helper.getWritableDatabase();
    }
    
    //插入
    public boolean insert(String tableName,String nullColumnHack,ContentValues values){
        boolean flag=false;
        long count=database.insert(tableName, nullColumnHack, values);
        flag=count>0?true:false;
        return flag;
    }
    //查询
    public Cursor queryByCursor(String table, String[] columns, String selection,
            String[] selectionArgs, String groupBy, String having,
            String orderBy){
        Cursor cursor=null;
        cursor=database.query(table, columns, selection, selectionArgs, groupBy, having, orderBy);
        
        return cursor;
        
        
    }
    //关闭数据库
    public void closeConn(){
        if(database!=null){database.close();}
        
    }
    
    

}

----------------------PersonServiceImp----------------------------------------------

public class PersonServiceImp implements PersonService {
private DBManger manger;
    public PersonServiceImp(Context context) {
        // TODO Auto-generated constructor stub
        manger=new DBManger(context);
    }

    @Override
    public Cursor listPersonCursor() {
        // TODO Auto-generated method stub
        return manger.queryByCursor("person", null,  null,  null,  null,  null,  null);
    }

    @Override
    public boolean addPerson(ContentValues values) {
        // TODO Auto-generated method stub
        boolean flag=false;
        flag=manger.insert("person", null, values);
        return flag;
    }

}

--------------------------MyTest()---------------------------------------------

public class MyTest extends AndroidTestCase {

    public MyTest() {
        // TODO Auto-generated constructor stub
    }

    public void insert(){
    
        
        PersonService service=new PersonServiceImp(getContext());
        ContentValues values=new ContentValues();
        values.put("name", "zy");
        values.put("address", "重庆");
        
        service.addPerson(values);
        
    }



}

----------------------MainActivity------------------------------------

public class MainActivity extends Activity implements LoaderCallbacks<Cursor> {
    private ListView listView;
    private android.widget.SimpleCursorAdapter adapter;
    private static PersonService service;
    private LoaderManager manager;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.fragment_main);
        service = new PersonServiceImp(this);
        Cursor cursor = service.listPersonCursor();
        listView = (ListView) this.findViewById(R.id.listView1);
        // String[]from={"name","address"};
        // int[]to={R.id.listView1,R.id.textView2};
        // adapter = new android.widget.SimpleCursorAdapter(this ,
        // R.layout.fragment_main, cursor,
        // from, to);
        // listView.setAdapter(adapter);

        manager = getLoaderManager();// 获得Loader的管理类
        manager.initLoader(1001, null, this);
        // 主线程调用loader
        manager.getLoader(1001).onContentChanged();

    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {

        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }

    /**
     * A placeholder fragment containing a simple view.
     */
    public static class PlaceholderFragment extends Fragment {

        public PlaceholderFragment() {
        }

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                Bundle savedInstanceState) {
            View rootView = inflater.inflate(R.layout.fragment_main, container,
                    false);
            return rootView;
        }
    }

    @Override
    public Loader<Cursor> onCreateLoader(int id, Bundle args) {
        // TODO Auto-generated method stub
        // 完成查询操作，把结果返回给调用者

        return new MyAsyncLoader(this);
    }

    // 更新UI操作
    @Override
    public void onLoadFinished(Loader<Cursor> loader, Cursor data) {
        // TODO Auto-generated method stub
        adapter = new android.widget.SimpleCursorAdapter(this,
                R.layout.fragment_main, data,
                new String[] { "name", "address" }, new int[] { R.id.textView1,
                        R.id.textView2 });
        listView.setAdapter(adapter);
        adapter.notifyDataSetChanged();
    }

    @Override
    public void onLoaderReset(Loader<Cursor> loader) {
        // TODO Auto-generated method stub

    }

    // 异步加载数据
    public static class MyAsyncLoader extends AsyncTaskLoader<Cursor> {

        public MyAsyncLoader(Context context) {
            super(context);
            // TODO Auto-generated constructor stub
        }

        @Override
        protected void onStartLoading() {
            // TODO Auto-generated method stub
            super.onStartLoading();
            // 如果内容改变，通知调用者
            if (takeContentChanged()) {
                forceLoad();

            }

        }

        // 完成查询操作
        @Override
        public Cursor loadInBackground() {
            // TODO Auto-generated method stub
            Cursor cursor = service.listPersonCursor();
            return cursor;
        }

    }

}