Android 数据库开发实例

package eoe.demo;  
import android.app.Activity;  
import android.database.Cursor;  
import android.database.sqlite.SQLiteCursor;  
import android.os.Bundle;  
import android.view.Menu;  
import android.view.MenuItem;  
import android.view.View;
import android.widget.AdapterView;  
import android.widget.EditText;  
import android.widget.ListView;  
import android.widget.SimpleCursorAdapter;  

public class DBActivity extends Activity {  
  private ToDoDB myToDoDB;  
  private Cursor myCursor;  
  private ListView myListView;  
  private EditText myEditText;  
  private int _id;  
  protected final static int MENU_ADD = Menu.FIRST;  
  protected final static int MENU_EDIT = Menu.FIRST + 1;  
  protected final static int MENU_DELETE = Menu.FIRST + 2;  
public boolean onOptionsItemSelected(MenuItem item)  
  
{  
super.onOptionsItemSelected(item);  
switch (item.getItemId())  
  
{  
  
case MENU_ADD:  
    this.addTodo();  
    break;  
case MENU_EDIT:  
    this.editTodo();  
    break;  
case MENU_DELETE:  
    this.deleteTodo();  
    break;  
}  
return true;  
}  
  
  
  
public boolean onCreateOptionsMenu(Menu menu)  
{  
super.onCreateOptionsMenu(menu);  
menu.add(Menu.NONE, MENU_ADD, 0, R.string.strAddButton);  
menu.add(Menu.NONE, MENU_EDIT, 0, R.string.strEditButton);  
menu.add(Menu.NONE, MENU_DELETE, 0, R.string.strDeleteButton);  
return true;  
}  
public void onCreate(Bundle savedInstanceState)  
{  
super.onCreate(savedInstanceState);  
setContentView(R.layout.main);  
myListView = (ListView) this.findViewById(R.id.myListView);  
myEditText = (EditText) this.findViewById(R.id.myEditText);  
myToDoDB = new ToDoDB(this);  
/** 取得DataBase里的数据 */
myCursor = myToDoDB.select();  
/** new SimpleCursorAdapter并将myCursor传入，
显示数据的字段为todo_text */  
SimpleCursorAdapter adapter =   
new SimpleCursorAdapter    
(this, R.layout.list, myCursor, new String[]  
{ ToDoDB.FIELD_TEXT }, new int[]  
{ R.id.listTextView1 });  
myListView.setAdapter(adapter);  
/** 将myListView添加OnItemClickListener */  
myListView.setOnItemClickListener  
(new AdapterView.OnItemClickListener()  
{  
public void onItemClick  
(AdapterView<?> arg0, View arg1, int arg2, long arg3)  
{  
/** 将myCursor移到所点击的值 */  
myCursor.moveToPosition(arg2);  
/** 取得字段_id的值 */  
_id = myCursor.getInt(0);  
/** 取得字段todo_text的值 */  
myEditText.setText(myCursor.getString(1));  
}  
});  
  
myListView.setOnItemSelectedListener  
(new AdapterView.OnItemSelectedListener()  
{  
public void onItemSelected  
(AdapterView<?> arg0, View arg1, int arg2, long arg3)  
{  
/** getSelectedItem所取得的是SQLiteCursor */  
SQLiteCursor sc = (SQLiteCursor) arg0.getSelectedItem();  
_id = sc.getInt(0);  
myEditText.setText(sc.getString(1));  
}  
  
public void onNothingSelected(AdapterView<?> arg0)  
{  
}  
});  
}  
  
private void addTodo()  
{  
if (myEditText.getText().toString().equals(""))  
return;  
/** 添加数据到数据库 */  
myToDoDB.insert(myEditText.getText().toString());  
/** 重新查询 */  
myCursor.requery();  
/** 重新整理myListView */  
myListView.invalidateViews();  
myEditText.setText("");  
_id = 0;  
}  
  
private void editTodo()  
{  
if (myEditText.getText().toString().equals(""))  
return;  
/** 修改数据 */  
myToDoDB.update(_id, myEditText.getText().toString());  
myCursor.requery();  
myListView.invalidateViews();  
myEditText.setText("");  
_id = 0;  
}  
  
private void deleteTodo()  
{  
if (_id == 0)  
return;  
/** 删除数据 */  
myToDoDB.delete(_id);  
myCursor.requery();  
myListView.invalidateViews();  
myEditText.setText("");  
_id = 0;  
}  
}