Android入門：ListView(繼承BaseAdapter實現)

任務：

從資料庫中獲得Person對象，通過繼承BaseAdapter類，顯示ListView，如下所示：

（此處我們資料庫操作的代碼略，因為主要講解的是ListView）

PersonAdapter.java

package org.xiazdong.db.domain;import java.util.List;import org.xiazdong.db.R;import android.content.Context;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.widget.BaseAdapter;import android.widget.TextView;public class PersonAdapter extends BaseAdapter {private List<Person> persons;//資料private int resource;//item的布局private Context context;private LayoutInflater inflator;private TextView nameTextView;private TextView ageTextView;private TextView idTextView;/** *  * @param context mainActivity * @param persons顯示的資料 * @param resource 一個Item的布局 */public PersonAdapter(Context context,List<Person>persons,int resource){this.context = context;this.persons = persons;this.resource = resource;}/* * 獲得資料總數 * */@Overridepublic int getCount() {return persons.size();}/* * 根據索引為position的資料 * */@Overridepublic Object getItem(int position) {return persons.get(position);}/* * 根據索引值獲得Item的Id * */@Overridepublic long getItemId(int position) {return position;}/* *通過索引值position將資料對應到視圖 *convertView具有緩衝功能，在第一頁時為null，在第二第三....頁時不為null * */@Overridepublic View getView(int position, View convertView, ViewGroup parent) {if(convertView==null){inflator = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);convertView = inflator.inflate(resource, null);nameTextView = (TextView)convertView.findViewById(R.id.name);//為了減少開銷，則只在第一頁時調用findViewByIdageTextView =(TextView) convertView.findViewById(R.id.age);idTextView = (TextView)convertView.findViewById(R.id.id1);}Person person = persons.get(position);nameTextView.setText(person.getName());idTextView.setText(person.getId()+"");ageTextView.setText(person.getAge()+"");return convertView;}}

MainActivity.java

package org.xiazdong.db;import java.util.List;import org.xiazdong.db.domain.Person;import org.xiazdong.db.domain.PersonAdapter;import org.xiazdong.db.service.DBService;import android.app.Activity;import android.os.Bundle;import android.widget.ListView;public class MainActivity extends Activity {private ListView listView;@Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.main);        listView = (ListView)this.findViewById(R.id.listview);        DBService service = new DBService(this);        List<Person> persons = service.pageQuery(0, 10);        PersonAdapter adapter = new PersonAdapter(this,persons, R.layout.item);        listView.setAdapter(adapter);}}