知識點(diǎn)13 sqlite數(shù)據(jù)庫綁定

數(shù)據(jù)綁定是指將界面和數(shù)據(jù)進(jìn)行綁定在界面和數(shù)據(jù)之間建立綁定模式有助于數(shù)據(jù)的呈現(xiàn)Adapter其實就是界面和數(shù)據(jù)之間綁定的橋梁將視圖和數(shù)據(jù)綁定后將會降低維護(hù)數(shù)據(jù)的復(fù)雜度SimpleCursorAdapter提供了數(shù)據(jù)層的數(shù)據(jù)綁定橋梁數(shù)據(jù)綁定的必要性SimpleCursorAdapter可以將數(shù)據(jù)庫層的數(shù)據(jù)提供給列表1、準(zhǔn)備一個列表項的布局用于ListView的展現(xiàn)SimpleCursorAdapter<LinearLayoutxmlns:android=""android:layout_width="match_parent"android:layout_height="match_parent"android:orientation="horizontal">

<TextViewandroid:id="@+id/nametextview“android:layout_width="0dp“android:layout_height="40dp“android:layout_weight="1"/><TextViewandroid:id="@+id/agetextview“android:layout_width="80dp"android:layout_height="40dp"/></LinearLayout>SimpleCursorAdapter可以將數(shù)據(jù)庫層的數(shù)據(jù)提供給列表2、使用SimpleCursorAdapter展現(xiàn)數(shù)據(jù)SimpleCursorAdapter2ListViewbookListView=(ListView)findViewById(R.id.booklist);String[]from=newString[]{"_name","_age“};int[]to=newint[]{R.textview,R.id.agetextview};Cursorcursor=db.rawQuery(“select*frombooks”,null);SimpleCursorAdapteradapter=newSimpleCursorAdapter(MainActivity.this,R.layout.book_list_item,cursor,from,to,0);bookListView.setAdapter(adapter);修改綁定數(shù)據(jù)有時候直接展現(xiàn)的數(shù)據(jù)可能不符合要求，需要轉(zhuǎn)變后展示可以通過SimpleCursorAdapter.ViewBinder接口來實現(xiàn)修改的步驟如下：1、編寫一個類實現(xiàn)SimpleCursorAdapter.ViewBinder接口修改綁定數(shù)據(jù)SimpleCursorAdapter.ViewBinderviewBinder=newSimpleCursorAdapter.ViewBinder(){publicbooleansetViewValue(Viewview,Cursorcursor,intcolumnIndex){if(cursor.getColumnIndex("_name")==columnIndex){TextViewv=(TextView)view;v.setText("N:"+cursor.getString(columnIndex));returntrue;}returnfalse;}};修改綁定數(shù)據(jù)修改的步驟如下：2、使用ViewBinder修改數(shù)據(jù)修改綁定數(shù)據(jù)2ListViewbookListView=(ListView)findViewById(R.id.booklist);String[]from=newString[]{"_name","_age“};int[]to=newint[]{R.textview,R.id.agetextview};Cursorcursor=db.rawQuery(“select*frombooks”,null);SimpleCursorAdapteradapter=newSimpleCursorAdapter(MainActivity.this,R.l