WindowsPhone 中SQL CE数据库的使用
在WindowsPhone中有时候我们会一些数据的存储，这个时候我们有两种选择，一种是选择存在的独立存储文件中，一种是存储在数据库中。存储在独立存储文件中，这个相信很多用都会使用，这里不作为重点，本文主要讲一下在WindowsPhone中使用数据库SQL CE。
下面开始一步一步的带领大家实现在WindowsPhone 中使用SQL CE数据库。（该示例引自WindowsPhone 7应用开发）
一、首先，我们需要创建一个EmployeeTable类，映射为数据库中的Employee表
如下：
在创建之前需要添加引用：System.Data.Linq；
同时引入命名空间：using System.Data.Linq.Mapping;
[Table]//特性标识该类为映射为数库中的表
//该类实现了INotifyPropertyChanged和INotifyPropertyChanging接口
public class EmployeeTable:INotifyPropertyChanged,INotifyPropertyChanging
{
private int _employeeId;
//将EmployeeID映射为表的主键，特性Column里的含义分别为：主键，自增，int型不为空，不为空等
[Column(IsPrimaryKey = true, IsDbGenerated = true,DbType = "INT NOT NULL Identity", CanBeNull = false, AutoSync = AutoSync.OnInsert)]
public int EmployeeID
{
get
{
return _employeeId;
}
set
{
if (_employeeId != value)
{
NotifyPropertyChanging("EmployeeID");
_employeeId = value;
NotifyPropertyChanged("EmployeeID");
}
}
}
private string _employeeName;
[Column]//EmployeeName属性为表中EmployeeName字段
public string EmployeeName
{
get
{
return _employeeName;
}
set
{
if (_employeeName != value)
{
NotifyPropertyChanging("EmployeeName");
_employeeName = value;
NotifyPropertyChanged("EmployeeName");
}
}
}
private string _employeeDesc;
[Column]//将EmployeeDesc属性映射为表中EmployeeDesc字段
public string EmployeeDesc
{
get
{
return _employeeDesc;
}
set
{
if (_employeeDesc != value)
{
NotifyPropertyChanging("EmployeeDesc");
_employeeDesc = value;
NotifyPropertyChanged("EmployeeDesc");
}
}
}
//定义PropertyChanged事件用来通知页面，表字段数据发生了改变
public event PropertyChangedEventHandler PropertyChanged;
private void NotifyPropertyChanged(string propertyName)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
//定义PropertyChanging事件通知数据上下文表的字段数据将要发生改变
public event PropertyChangingEventHandler PropertyChanging;
private void NotifyPropertyChanging(string propertyname)
{
if (PropertyChanging != null)
{
PropertyChanging(this, new PropertyChangingEventArgs(propertyname));
}
}
}
通过以上的这些操作，我们已经基本上完成了Employee表的创建，映射为数据库中的EmployeeTable表
二、下面我们来新建一个EmployeeDataContext.cs类文件，创建数据库的DataContent，该类继承自DataContent,在该类中定义连接字符串，如下：
首先需要引入命名空间：using system.data.Linq;
public class EmployeeDataContext:DataContext
{
//数据库连接字符串
public static string DBConnectionString = "Data Source=isostore:/Employee.sdf";
//传递数据库连接字符串到DataContext基类
public EmployeeDataContext(string connectionString):base(connectionString)
{
}
//定义员工信息表
public Table<EmployeeTable> Employees;
}
三、创建EmployeeCollection类，该类的主要作用为页面数据绑定的集合。如下：
//绑定页面，进行显示用
public class EmployeeCollection:INotifyPropertyChanged
{
//用于通知属性的改变
public event PropertyChangedEventHandler PropertyChanged;
public void NotifyPropertyChanged(string propertyName)
{
if (PropertyChanged != null)
{
PropertyChanged(this,new PropertyChangedEventArgs (propertyName));
}
}
private ObservableCollection<EmployeeTable> _employeeTables;
//创建EmployeeTables属性用来绑定页面数据
public ObservableCollection<EmployeeTable> EmployeeTables
{
get
{
return _employeeTables;
}
set
{
if (_employeeTables != value)
{
_employeeTables = value;
NotifyPropertyChanged("EmployeeTables");
}
}
}
}
四、这样一个完整的数据库就创建完毕了，那么我们该如何使用呢？一般的情况下我们都是在程序启动的时候加载数据库，为此我们可以在App.xaml文件的Launching事件中做如下处理：
using (EmployeeDataContext db=new EmployeeDataContext(EmployeeDataContext.DBConnectionString))
{
if (db.DatabaseExists() == false)
{
db.CreateDatabase();
}
}
五、下面做一个实例进行演示：
页面布局如下：
<phone:PhoneApplicationPage.Resources>
<DataTemplate x:Key="listitem">
<Grid HorizontalAlignment="Stretch" Width="440">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="50"/>
<ColumnDefinition Width="*"/>
<ColumnDefinition Width="100"/>
</Grid.ColumnDefinitions>
<TextBlock Text="{Binding EmployeeName}" FontSize="{StaticResource PhoneFontSizeLarge}" Grid.Column="1"
VerticalAlignment="Center"/>
<Button Grid.Column="2" Click="deleteButton_Click" x:Name="deleteButton" BorderThickness="0" Margin="0" Content="删除" ></Button>
<Button Grid.Column="1" x:Name="editButton" Click="editButton_Click"BorderThickness="0" Margin="209,0,81,0" Content="编辑"
Grid.ColumnSpan="2"></Button>
</Grid>
</DataTemplate>
</phone:PhoneApplicationPage.Resources>
<!--LayoutRoot 是包含所有页面内容的根网格-->
<Grid x:Name="LayoutRoot" Background="Transparent">
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
<RowDefinition Height="*"/>
</Grid.RowDefinitions>
<!--TitlePanel 包含应用程序的名称和页标题-->
<StackPanel x:Name="TitlePanel" Grid.Row="0" Margin="12,17,0,28">
<TextBlock x:Name="ApplicationTitle" Text="我的应用程序" Style="{StaticResource PhoneTextNormalStyle}"/>
<TextBlock x:Name="PageTitle" Text="EmployeeShow" Margin="9,-7,0,0" Style="{StaticResource PhoneTextTitle1Style}"/>
</StackPanel>
<!--ContentPanel - 在此处放置其他内容-->
<Grid x:Name="ContentPanel" Grid.Row="1" Margin="12,0,12,0">
<TextBlock FontSize="24" Name="textBlock1" Text="员工名字：
" Margin="12,22,330,544" />
<TextBlock FontSize="24" Margin="12,93,330,473" Name="textBlock2" Text="简介：" />
<TextBox Height="72" HorizontalAlignment="Left" Margin="132,6,0,0" Name="txtname" Text=""
VerticalAlignment="Top" Width="281" />
<TextBox Height="72" HorizontalAlignment="Left" Margin="132,78,0,0" Name="txtdesc" Text=""
VerticalAlignment="Top" Width="281" />
<Button Content="保存" Height="72" HorizontalAlignment="Left" Margin="243,150,0,0" Name="button2"
VerticalAlignment="Top" Width="160" Click="button2_Click" />
<ListBox Height="293" HorizontalAlignment="Left" Margin="-12,228,0,0" Name="listBox1" VerticalAlignment="Top"
Width="460" ItemTemplate="{StaticResource listitem}" />
</Grid>
</Grid>
</phone:PhoneApplicationPage>
.cs页的处理代码如下：
public partial class EmployeeShow : PhoneApplicationPage
{
//创建DataContext用于操作独立的数据库
private EmployeeDataContext employeeDB;
private EmployeeCollection employeeCol = new EmployeeCollection();
public EmployeeShow()
{
InitializeComponent();
//创建EmployeeDataContext实例
employeeDB = new EmployeeDataContext(EmployeeDataContext.DBConnectionString);
var employeeInDB = from EmployeeTable employee in employeeDB.Employees
select employee;
//为页面创建数据绑定源
employeeCol.EmployeeTables = new System.Collections.ObjectModel.ObservableCollection<EmployeeTable>(employeeInDB);
listBox1.ItemsSource = employeeCol.EmployeeTables;
}
//删除信息
private void deleteButton_Click(object sender, RoutedEventArgs e)
{
var button = sender as Button;
if (button != null)
{
EmployeeTable edelete = button.DataContext as EmployeeTable;
//
employeeCol.EmployeeTables.Remove(edelete);
employeeDB.Employees.DeleteOnSubmit(edelete);
employeeDB.SubmitChanges();
}
}
//保存信息
private void button2_Click(object sender, RoutedEventArgs e)
{
if (txtname.Text != "" && txtdesc.Text != "")
{
//编辑状态
if (State.Count > 0 && State["employee"] != null)
{
EmployeeTable employee = (EmployeeTable)State["employee"];
employee.EmployeeName = txtname.Text;
employee.EmployeeDesc = txtdesc.Text;
employeeDB.SubmitChanges();
employeeCol.EmployeeTables.Add(employee);
State["employee"] = null;
}
Else//添加新的信息
{
EmployeeTable newEmployee = new EmployeeTable
{
EmployeeName = txtname.Text,
EmployeeDesc = txtdesc.Text
};
employeeCol.EmployeeTables.Add(newEmployee);
employeeDB.Employees.InsertOnSubmit(newEmployee);
employeeDB.SubmitChanges();
txtname.Text = "";
txtdesc.Text = "";
}
listBox1.ItemsSource = employeeCol.EmployeeTables;
}
else
{
MessageBox.Show("姓名和简介不能为空！");
}
}
//编辑信息
private void editButton_Click(object sender, RoutedEventArgs e)
{
var button = sender as Button;
if (button != null)
{
EmployeeTable eedit = button.DataContext as EmployeeTable;
txtname.Text = eedit.EmployeeName;
txtdesc.Text = eedit.EmployeeDesc;
State["employee"] = eedit;
employeeCol.EmployeeTables.Remove(eedit)；
}
}
}
效果如图：
好了，到这里我们已经基本上实现了在WindowsPhone手机中使用SQLCE数据库了，希望可以对朋友们有所帮助。