Android入门：ListView(继承BaseAdapter实现)

任务：

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
* */
@Override
public int getCount() {
return persons.size();
}
/*
* 根据索引为position的数据
* */
@Override
public Object getItem(int position) {
return persons.get(position);
}
/*
* 根据索引值获得Item的Id
* */
@Override
public 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
* */
@Override
public 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findViewById
ageTextView =(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;
}
}

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);
}
}