任务：
从数据库中获得Person对象，，通过继承BaseAdapter类，显示ListView，如下所示：
（此处我们数据库操作的代码略，因为主要讲解的是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;//数据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显示的数据 * @param resource 一个Item的布局 */public PersonAdapter(Context context,List<Person>persons,int resource){this.context = context;this.persons = persons;this.resource = resource;}/* * 获得数据总数 * */@Overridepublic int getCount() {return persons.size();}/* * 根据索引为position的数据 * */@Overridepublic Object getItem(int position) {return persons.get(position);}/* * 根据索引值获得Item的Id * */@Overridepublic long getItemId(int position) {return position;}/* *通过索引值position将数据映射到视图 *convertView具有缓存功能，在第一页时为null，在第二第三….页时不为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);//为了减少开销，则只在第一页时调用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;@Overridepublic 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);}}
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