simpleAdapter，cursorAdapter，arrayAdapter学习

package cn.itcast.db;import java.util.ArrayList;import java.util.HashMap;import java.util.List;import java.util.Map;import cn.itcast.db.dao.PersonDBDao;import cn.itcast.db.domain.Person;import android.app.Activity;import android.database.Cursor;import android.database.DataSetObserver;import android.os.Bundle;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.widget.AdapterView;import android.widget.AdapterView.OnItemClickListener;import android.widget.ArrayAdapter;import android.widget.BaseAdapter;import android.widget.ListAdapter;import android.widget.ListView;import android.widget.SimpleAdapter;import android.widget.SimpleCursorAdapter;import android.widget.TextView;import android.widget.Toast;public class DbActivity extends Activity {private ListView mListView;private List<Person> persons;private LayoutInflater inflater; // 打气筒 ,充气泵@Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);// inflater 是系统的一个服务 初始化服务inflater = (LayoutInflater) this.getSystemService(LAYOUT_INFLATER_SERVICE);setContentView(R.layout.main);// 第一步得到 组件的id的引用mListView = (ListView) this.findViewById(R.id.lv_all_person);PersonDBDao dao = new PersonDBDao(this);persons = dao.findAll();// 第二步 设置组件要显示的内容// listview 显示的东西 比较复杂,需要数据的适配器// mListView.setAdapter(new MyAdatper());List<Map<String, String>> data = new ArrayList<Map<String, String>>();for (Person person : persons) {HashMap<String, String> map = new HashMap<String, String>();map.put("name", person.getName());map.put("age", person.getAge() + "");data.add(map);}String [] personarr = new String[persons.size()];for(int i=0;i<persons.size();i++){personarr[i]= persons.get(i).getName();}/*mListView.setAdapter(new SimpleAdapter(DbActivity.this, data, R.layout.item,new String[]{"name","age"}, new int[]{R.id.tv_name,R.id.tv_age}));*///mListView.setAdapter(new ArrayAdapter<String>(DbActivity.this, R.layout.item, R.id.tv_name, personarr));Cursor c = dao.findAllbyCursor();mListView.setAdapter(new SimpleCursorAdapter(this, R.layout.item, c,new String[] { "name", "age" }, new int[] { R.id.tv_name,R.id.tv_age }));mListView.setOnItemClickListener(new OnItemClickListener() {/** * parent 代表的是当前的listview view 代表的当前被点击条目对应的view对象 position * 当前条目在listview中的位置 id 行号 一般与position 相同的 */public void onItemClick(AdapterView<?> parent, View view,int position, long id) {/* * 方法1 TextView tv_name = (TextView) * view.findViewById(R.id.tv_name); String name = * tv_name.getText().toString(); Toast.makeText(DbActivity.this, * name, Toast.LENGTH_LONG).show(); *//* * 方法2 String name = persons.get(position).getName(); * Toast.makeText(DbActivity.this, name, * Toast.LENGTH_LONG).show(); */Person object = (Person) parent.getItemAtPosition(position);String name = object.getName();Toast.makeText(DbActivity.this, name, Toast.LENGTH_LONG).show();}});}// BaseAdapter 是 google的工程师 给ListAdapter的默认实现public class MyAdatper extends BaseAdapter {/** * 返回当前listview有多少个条目 */public int getCount() {return persons.size();}/** * 返回当前position位置对应的条目 的object对象 */public Object getItem(int position) {return persons.get(position);}/** * 返回当前position位置 某个条目的id */public long getItemId(int position) {return position;}/** * 返回每一个条目显示的具体内容 *  * 计算当前界面 会有多少个条目出现 1.得到每一个textview的高度 2.得到listview的高度 3. listview高度/ * textview高度 = 得到了一个屏幕显示的textview的个数 *  * listview的每一个条目的显示 都需要调用一次getview的方法 屏幕上有多个item显示 就会调用多少getview的方法 * parent 代表的是 当前的这个listview */public View getView(int position, View convertView, ViewGroup parent) {/* * TextView tv = new TextView(DbActivity.this); * //tv.setText("我是第"+position+"个文本"); Person person = * persons.get(position); tv.setText(person.getName() +" | "+ * person.getAge() ); System.out.println("我被调用了 "+ position); return * tv; */View view = inflater.inflate(R.layout.item, null);Person person = persons.get(position);TextView tv_age = (TextView) view.findViewById(R.id.tv_age);TextView tv_name = (TextView) view.findViewById(R.id.tv_name);tv_age.setText("年龄为 " + person.getAge());tv_name.setText("姓名:" + person.getName());System.out.println("我被调用了 " + position);return view;}}}