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Android -- CursorAdapter

2024-08-01 15:18:59   215人阅读

CursorAdapter                                                                       

CursorAdapter继承于BaseAdapter,它是个虚类,它为cursor和ListView提供了连接的桥梁。  

public abstract class CursorAdapter extends BaseAdapter

注意cursor的必须要有个命名为"_id"的列。比如Contacts._ID就为"_id"

必须实现以下函数：

abstract View newView(Context  context, Cursor  cursor, ViewGroup  parent)    abstract void  bindView(View  view, Context  context, Cursor  cursor)

newView该函数第一次回调用后，如果数据增加后也会再调用，但是重绘是不会调用的。
数据增加后,回调用该函数来生成与新增数据相对应的view。
bindView函数第一次回调用后，如果数据更新也会再调用，但重绘会再次调用的。

总的来说应该是在调用bindView如果发现view为空会先调用newView来生成view。

Code                                                                                    

public class MySqliteOpenhelper extends SQLiteOpenHelper {                                                                        public MySqliteOpenhelper(Context context,  int version)     {         super(context, "dianhuaben.db", null, version);     }     @Override    public void onCreate(SQLiteDatabase db)     {//注意：使用CursorAdapter时，创建表必须有以_id为列名的列         String sql = "CREATE TABLE dhb (_id INTEGER PRIMARY KEY AUTOINCREMENT,name VARCHAR(20),phone VARCHAR(20))";         db.execSQL(sql);     }     @Override    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion)     {     } }
public void createCursorAdapter(Cursor cursor)     { //游标适配器,构造方法，传入cursor         mAdapter = new CursorAdapter(this, cursor)         {//重写两个方法             @Override            public View newView(Context context, Cursor cursor, ViewGroup parent)             {//找到布局和控件                 ViewHolder holder = new ViewHolder();                 LayoutInflater inflater = getLayoutInflater();                 View inflate = inflater.inflate(R.layout.listview_item, null);                 holder.item_tv_name = (TextView) inflate.findViewById(R.id.item_tv_name);                 holder.item_tv_phone = (TextView) inflate.findViewById(R.id.item_tv_phone);                 inflate.setTag(holder);                 return inflate;//返回的view传给bindView。             }                                                                           @Override            public void bindView(View view, Context context, Cursor cursor)             {//                把数据设置到界面上                 ViewHolder holder = (ViewHolder) view.getTag();                 String name = cursor.getString(cursor.getColumnIndex("name"));                 String phone = cursor.getString(cursor.getColumnIndex("phone"));                 holder.item_tv_name.setText(name);                 holder.item_tv_phone.setText(phone);             }                                                                   };                                                         };

SimpleCursorAdapter                                                                

简单提及一下

public void createSimpleCursorAdapter(Cursor cursor)     {// SimpleCursorAdapter继承了CursorAdapter继承了BaseAdapter         String[] from = {TABLE_NAME_NAME,TABLE_NAME_PHONE};//列名与控件id一一对应         int[] to = {R.id.item_tv_name,R.id.item_tv_phone};         //用的是SimpleCursorAdapter，用法和simpleAdapter相似         mAdapter = new SimpleCursorAdapter(MainActivity.this, R.layout.listview_item, cursor, from, to);     }

使用SimpleCursorAdapter，时，创建表必须有以_id为列名的列

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Android -- CursorAdapter


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