小程序源码 学习相关 操作数据库实例.rar

package com.test; 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; }}