PhoneApplicationService的任务在于控制Windows Phone 7 application 在任何状态下的寿命，包括Application在idle阶段时该处理的任务，管理Application状态改变时触发的事件，常用来保存Application的状态和设置。
1.首先我们需要建一个PhoneApplicationService对象，用来管理状态。
PhoneApplicationService phoneAppServeice = PhoneApplicationService.Current;
2.在App.cs中添加俩个方法，用来加载Application状态和保存Application状态。
1）加载方法如下：
private void LoadState()
{ PhoneApplicationService phoneAppServeice = PhoneApplicationService.Current; IsolatedStorageSettings settings = IsolatedStorageSettings.ApplicationSettings;string myValue;
if (settings.TryGetValue<string>("MyValue",out myValue))
{ phoneAppServeice.State["MyValue"]=myValue; } }2）保存方法如下：
private void SaveState()
{ PhoneApplicationService phoneAppServeice = PhoneApplicationService.Current; IsolatedStorageSettings settings = IsolatedStorageSettings.ApplicationSettings;if (phoneAppServeice.State.ContainsKey("MyValue"))
{ settings["MyValue"] = phoneAppServeice.State["MyValue"]; } }3.在App.cs事件中使用上诉俩个方法
private void Application_Launching(object sender, LaunchingEventArgs e)
{ LoadState(); } private void Application_Activated(object sender, ActivatedEventArgs e) { LoadState(); } private void Application_Deactivated(object sender, DeactivatedEventArgs e) { SaveState(); } private void Application_Closing(object sender, ClosingEventArgs e) { SaveState(); }
4.在MainPage.xaml.cs中获取值和保存值
1）保存如下
private void myTextBox_TextChanged(object sender, TextChangedEventArgs e)
{ phoneAppServeice.State["MyValue"] = myTextBox.Text;}
2）获取如下
private void PhoneApplicationPage_Loaded(object sender, RoutedEventArgs e)
{ object myValue;if (phoneAppServeice.State.ContainsKey("MyValue"))
{ if (phoneAppServeice.State.TryGetValue("MyValue", out myValue)) { this.myTextBox.Text = myValue.ToString(); } }}
5.测试方法
1)启动Application，在文本域中输入数据。
2)按"back"键退出Application。
3)再次进入Application，你会看到你输入的数据是一致的。
4)再按"start"键退出Application。
5）再次进入和上诉3一样
这说明值保存成功！
效果图如下
6.