Android心得4.5--SQLite数据库--事务处理、ListView列表显示
1. 使用SQLiteDatabase的beginTransaction()方法可以开启一个事务，程序执行到endTransaction() 方法时会检查事务的标志是否为成功，如果程序执行到endTransaction()之前调用了setTransactionSuccessful() 方法设置事务的标志为成功则提交事务，如果没有调用setTransactionSuccessful() 方法则回滚事务。使用例子如下：
SQLiteDatabase db = ....;
db.beginTransaction();//开始事务
try {
db.execSQL("insert into person(name, age) values(?,?)", new Object[]{"传智播客", 4});
db.execSQL("update person set name=? where personid=?", new Object[]{"传智", 1});
db.setTransactionSuccessful();//调用此方法会在执行到endTransaction() 时提交当前事务，如果不调用此方法会回滚事务
} finally {
db.endTransaction();//由事务的标志决定是提交事务，还是回滚事务
}
db.close();
上面两条SQL语句在同一个事务中执行。
2.ListView列表显示
先在Layout文件夹下创建一个item.xml文件，水平线性布局显示文件，然后在main.xml文件下引用<ListView/>.
网格显示跟列表显示基本上一样。
有三种方法可以完成操作，分别是下面代码的show()、show2()、show3()，show3()是自定义的适配器，某些特殊情况下会用到。
代码如下：
package cn.itcast.db;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import cn.itcast.adapter.PersonAdapter;
import cn.itcast.domain.Person;
import cn.itcast.service.PersonService;
import android.app.Activity;
import android.database.Cursor;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.SimpleCursorAdapter;
import android.widget.Toast;
public class MainActivity extends Activity {
private ListView listView;
private PersonService personService;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
personService = new PersonService(this);
listView = (ListView) this.findViewById(R.id.listView);
listView.setOnItemClickListener(new ItemClickListener());
show2();
}
private final class ItemClickListener implements OnItemClickListener{
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
ListView lView = (ListView)parent;
/* 自定义适配器
Person person = (Person) lView.getItemAtPosition(position);
Toast.makeText(getApplicationContext(), person.getId().toString(), 1).show();*/
Cursor cursor = (Cursor) lView.getItemAtPosition(position);
int personid = cursor.getInt(cursor.getColumnIndex("_id"));
Toast.makeText(getApplicationContext(), personid+ "", 1).show();
}
}
//自定义适配器
private void show3() {
List<Person> persons = personService.getScrollData(0, 20);
PersonAdapter adapter = new PersonAdapter(this, persons, R.layout.item);
listView.setAdapter(adapter);
}
private void show2() {
Cursor cursor = personService.getCursorScrollData(0, 20);
SimpleCursorAdapter adapter = new SimpleCursorAdapter(this, R.layout.item, cursor,
new String[]{"name", "phone", "amount"}, new int[]{R.id.name, R.id.phone, R.id.amount});
listView.setAdapter(adapter);
}
private void show() {
List<Person> persons = personService.getScrollData(0, 20);
List<HashMap<String, Object>> data = new ArrayList<HashMap<String,Object>>();
for(Person person : persons){
HashMap<String, Object> item = new HashMap<String, Object>();
item.put("name", person.getName());
item.put("phone", person.getPhone());
item.put("amount", person.getAmount());
item.put("id", person.getId());
data.add(item);
}
SimpleAdapter adapter = n
补充：移动开发 , Android ,
