WPF技术的最显著的特点是实现了UI和逻辑业务的分离，并用数据绑定来关联两者。本文通过一个简单的实例来总结一下WPF中数据绑定的方法，本例还用到了数据库操作和泛型集合的使用方法。
1. UI和功能
左上方Border区域内有三个Label控件、三个TextBox控件和三个Button控件，TextBox控件用于接收用户输入和显示选择的内容，Button控件分别实现数据库的添加、删除、修改操作。右上Border区域内有两个Label控件、一个Combo控件、一个TextBox控件和一个Button控件，左下为DataGrid控件，右下为ListView控件。程序启动时DataGrid控件显示数据库tb_User表中所有的元素，ListView控件显示按条件查询的结果，鼠标可以从DataGrid控件、ListView控件中选择条目，显示在左上的TextBox控件中，从而进行修改和删除操作。
代码如下，其中数据绑定部分关键代码加粗标出，后面再解释。
<Window
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:WPF" x:Class="WPF.MainWindow"
Title="用户设置" Height="720"Width="1024"Background="{DynamicResource{x:StaticSystemColors.ControlBrushKey}}" ResizeMode="NoResize"FontSize="14">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="265*"/>
<ColumnDefinition Width="243*"/>
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="330*"/>
<RowDefinition Height="359*"/>
</Grid.RowDefinitions>
<TextBox x:Name="tbx_User"HorizontalAlignment="Left" Height="35"Margin="160,80,0,0"TextWrapping="Wrap"VerticalAlignment="Top" Width="150"FontSize="16" BorderBrush="{DynamicResource {x:Static SystemColors.ControlDarkDarkBrushKey}}"/>
<TextBox x:Name="tbx_KeyWord"HorizontalAlignment="Left" Height="35"Margin="160,160,0,0"TextWrapping="Wrap"VerticalAlignment="Top" Width="150"FontSize="16" BorderBrush="{DynamicResource {x:Static SystemColors.ControlDarkDarkBrushKey}}"/>
<TextBox x:Name="tbx_Auth"HorizontalAlignment="Left" Height="35"Margin="160,240,0,0"TextWrapping="Wrap" VerticalAlignment="Top"Width="150" FontSize="16"BorderBrush="{DynamicResource{x:StaticSystemColors.ControlDarkDarkBrushKey}}"/>
<Button x:Name="btn_Add" Content="添加用户"HorizontalAlignment="Left" Height="40"Margin="360,80,0,0"VerticalAlignment="Top" Width="120"FontSize="16" Click="btn_Add_Click"/>
<Button x:Name="btn_Remove"Content="删除用户"HorizontalAlignment="Left" Height="40"Margin="360,160,0,0"VerticalAlignment="Top" Width="120"FontSize="16" Click="btn_Remove_Click"/>
<Button x:Name="btn_Upate"Content="编辑用户"HorizontalAlignment="Left" Height="40"Margin="360,240,0,0"VerticalAlignment="Top" Width="120"FontSize="16" Click="btn_Upate_Click"/>
<Label Content="用户名"HorizontalAlignment="Left" Height="40"Margin="60,75,0,0"VerticalAlignment="Top" Width="80"FontSize="16"/>
<Label Content="密码"HorizontalAlignment="Left" Height="40"Margin="60,155,0,0"VerticalAlignment="Top" Width="80"FontSize="16"/>
<Label Content="权限"HorizontalAlignment="Left" Height="40"Margin="60,235,0,0"VerticalAlignment="Top" Width="80"FontSize="16"/>
<Border BorderBrush="Black"BorderThickness="1" HorizontalAlignment="Left"Height="305" Margin="20,20,0,0"VerticalAlignment="Top" Width="490"/>
<ComboBox x:Name="cbx_condition"Grid.Column="1" HorizontalAlignment="Left"Height="35" Margin="200,80,0,0"VerticalAlignment="Top" Width="165"FontSize="16">
<ComboBoxItem Content="按用户名"/>
<ComboBoxItem Content="按用户权限"/>
</ComboBox>
<Label Content="查询条件"Grid.Column="1" HorizontalAlignment="Left"Height="40" Margin="60,80,0,0"VerticalAlignment="Top" Width="100"FontSize="16"/>
<Button x:Name="btn_Select"Content="查询"Grid.Column="1" HorizontalAlignment="Left"Height="40" Margin="200,235,0,0"VerticalAlignment="Top" Width="160"FontSize="16" Click="btn_Select_Click"/>
<TextBox x:Name="tbx_forselect"Grid.Column="1" HorizontalAlignment="Left"Height="40" Margin="200,160,0,0"TextWrapping="Wrap"VerticalAlignment="Top" Width="160"FontSize="16"/>
<Label Content="关键字"Grid.Column="1" HorizontalAlignment="Left"Height="40" Margin="60,160,0,0"VerticalAlignment="Top" Width="100"FontSize="16"/>
<Border BorderBrush="Black"BorderThickness="1" Grid.Column="1"HorizontalAlignment="Left" Height="305"Margin="5,20,0,0"VerticalAlignment="Top" Width="460"/>
<DataGrid x:Name="GridView1"HorizontalAlignment="Left" Margin="20,50,0,0"Grid.Row="1" VerticalAlignment="Top"Height="290" Width="490"BorderBrush="{DynamicResource{x:StaticSystemColors.ActiveCaptionTextBrushKey}}"IsReadOnly="True"SelectionChanged="GridView1_SelectionChanged" <strong><span style="color:#ff0000;">ItemsSource="{Binding LT,RelativeSource={RelativeSource FindAncestor,AncestorType={x:Type local:MainWindow}}}" ></span></strong>
<DataGrid.ItemBindingGroup>
<BindingGroup/>
</DataGrid.ItemBindingGroup>
</DataGrid>
<Label Content="用户列表"HorizontalAlignment="Left" Height="40"Margin="25,10,0,0" Grid.Row="1"VerticalAlignment="Top" Width="135"FontSize="16"/>
<Label Content="查询结果"HorizontalAlignment="Left" Height="40"Margin="20,15,0,0" Grid.Row="1"VerticalAlignment="Top" Width="135"FontSize="16" Grid.Column="1"/>
<ListView x:Name="ListView1"Grid.Column="1" HorizontalAlignment="Left"Height="290" Margin="5,50,0,0"Grid.Row="1" VerticalAlignment="Top"Width="460" BorderBrush="{DynamicResource {x:Static SystemColors.ActiveCaptionTextBrushKey}}"<span style="color:#ff0000;"><strong>ItemsSource="{Binding DataList,RelativeSource={RelativeSource FindAncestor,AncestorType={x:Type local:MainWindow}}}"</strong></span>SelectionChanged="ListView1_SelectionChanged">
<ListView.View>
<GridView>
<GridViewColumn Header="UserID"Width="230"<span style="color:#ff0000;"><strong>DisplayMemberBinding="{BindingUserID}"</strong></span>/>
<GridViewColumnHeader="Auth" Width="230"<strong><span style="color:#ff0000;">DisplayMemberBinding="{Binding Auth}"</span></strong>/>
</GridView>
</ListView.View>
</ListView>
</Grid>
</Window>
2. 数据库定义
数据库用Microsoft SQL Server 2008创建，名为db_Nord，其中有一个表tb_User，字段和初始内容如下图，后面程序只对本表操作。
3. 类设计
3.1 首先将数据库操作相关的方法封装为类DatabaseClass，其代码如下：
using System;
using System.Collections.Generic;
using System.Data;
using System.Data.SqlClient;
using System.Windows;
namespace WPF.ClassLib
{
public class DatabaseClass
{
private string ConnectionString=Properties.Settings.Default.ConnectionString;
#region 连接数据库
private SqlConnection GetConnection()
{
try
{
SqlConnection sqlcon = new SqlConnection("Data Source=WIN-01410121400\\SQLEXPRESS;Initial Catalog=db_Nord;User ID=sa;Password=admin2016");
return sqlcon;
}
catch (Exception ex)
{
MessageBox.Show(ex.Message, "数据库连接失败");
return null;
}
}
#endregion
#region 从SqlDataReader对象生成类成员列表
private List<UserClass> GetList(SqlDataReader sdr)
{
List<UserClass> lt =new List<UserClass>();
while (sdr.Read())
{
lt.Add(new UserClass(sdr[0].ToString(),sdr[1].ToString(),sdr[2].ToString()));
}
return lt;
}
#endregion
#region 增加记录
public void Add(UserClass user)
{
SqlConnection sc = GetConnection();
try
{
sc.Open();
SqlCommand cmd = new SqlCommand();
cmd.Connection = sc;
cmd.CommandType = CommandType.Text;
cmd.CommandText = "INSERT INTO tb_User(UserID,KeyWord,Auth)VALUES(@UserID,@KeyWord,@Auth)";
cmd.Parameters.Add("@UserID",SqlDbType.VarChar).Value=user.UserID;
cmd.Parameters.Add("@KeyWord", SqlDbType.VarChar).Value = user.KeyWord;
cmd.Parameters.Add("@Auth", SqlDbType.VarChar).Value = user.Auth;
cmd.ExecuteNonQuery();
}
catch(Exception ex)
{
MessageBox.Show(ex.Message, "添加记录失败");
}
finally
{
if (sc.State==ConnectionState.Open)
{
sc.Close();
}
}
}
#endregion
#region 删除记录
public void Remove(string UserID)
{
SqlConnection sc = GetConnection();
try
{
sc.Open();
SqlCommand cmd = new SqlCommand();
cmd.Connection = sc;
cmd.CommandType = CommandType.Text;
cmd.CommandText = "DELETE FROM tb_user WHERE UserID=@UserID";
cmd.Parameters.Add("@UserID",SqlDbType.VarChar).Value=UserID;
cmd.ExecuteNonQuery();
}
catch(Exception ex)
{
MessageBox.Show(ex.Message, "删除记录失败");
}
finally
{
if (sc.State==ConnectionState.Open)
{
sc.Close();
}
}
}
#endregion
#region 更新记录
public void Update(UserClass User)
{
SqlConnection sc = GetConnection();
try
{
sc.Open();
SqlCommand cmd = new SqlCommand();
cmd.Connection = sc;
cmd.CommandType = CommandType.Text;
cmd.CommandText = "UPDATE tb_user SET UserID=@UserID,KeyWord=@KeyWord,Auth=@Auth WHERE UserID=@UserID";
cmd.Parameters.Add("@UserID", SqlDbType.VarChar).Value = User.UserID;
cmd.Parameters.Add("@KeyWord", SqlDbType.VarChar).Value = User.KeyWord;
cmd.Parameters.Add("@Auth", SqlDbType.VarChar).Value = User.Auth;
cmd.ExecuteNonQuery();
}
catch (Exception ex)
{
MessageBox.Show(ex.Message, "更改记录失败");
}
finally
{
if (sc.State == ConnectionState.Open)
{
sc.Close();
}
}
}
#endregion
# region 查询全部记录
public List<UserClass> Select()
{
SqlConnection sc = GetConnection();
try
{
sc.Open();
SqlCommand cmd = new SqlCommand();
cmd.Connection = sc;
cmd.CommandType = CommandType.Text;
cmd.CommandText = "SELECT * FROM tb_user";
return GetList(cmd.ExecuteReader());
}
catch (Exception ex)
{
MessageBox.Show(ex.Message, "查找记录失败");
return null;
}
finally
{
if (sc.State == ConnectionState.Open)
{
sc.Close();
}
}
}
#endregion
# region 按SQL语句查询记录
public List<UserClass> ConditionSelect(SqlCommand SQLstr)
{
SqlConnection sc = GetConnection();
try
{
sc.Open();
SqlCommand cmd =SQLstr;
cmd.Connection = sc;
return GetList(cmd.ExecuteReader());
}
catch (Exception ex)
{
MessageBox.Show(ex.Message, "查找记录失败");
return null;
}
finally
{
if (sc.State == ConnectionState.Open)
{
sc.Close();
}
}
}
#endregion
}
}
3.2 将数据实体对象封装为UserClass类，提供给WPF绑定数据源，代码如下：
namespace WPF.ClassLib
{
public class UserClass
{
private string userid;
private string keyword;
private string auth;
public string UserID
{
get { return userid; }
set { userid = value; }
}
public string KeyWord
{
get { return keyword; }
set { keyword = value; }
}
public string Auth
{
get { return auth; }
set { auth = value; }
}
public UserClass(string userid, string keyword, string auth)
{
this.UserID = userid;
this.KeyWord = keyword;
this.Auth = auth;
}
}
}
4. 主程序代码
主程序代码启动时读取数据库tb_User表中所有的内容并显示在DataGrid控件中，还要实现文本框的一些操作。另外数据绑定必须定义依赖属性，因此定义了ObservableCollection<T>泛型集合和List <T>泛型列表公共属性，ListView、DataGrid控件分别绑定到其公共属性上。代码如下：
using System;
using System.Collections.Generic;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using WPF.ClassLib;
using System.Data;
using System.Data.SqlClient;
using System.Collections.ObjectModel;
namespace WPF
{
/// <summary>
/// MainWindow.xaml 的交互逻辑
/// </summary>
public partial class MainWindow : Window
{
DatabaseClass dt = new DatabaseClass();
private ObservableCollection<UserClass> datalist = new ObservableCollection<UserClass>();
public ObservableCollection<UserClass> DataList
{
get { return this.datalist; }
}
private List<UserClass> lt = new List<UserClass>();
public List<UserClass> LT
{
get { return this.lt; }
}
public MainWindow()
{
InitializeComponent();
lt = dt.Select();
cbx_condition.SelectedIndex=0;
}
private void btn_Add_Click(object sender, RoutedEventArgs e)
{
if (tbx_User.Text != "" && tbx_KeyWord.Text != "" && tbx_Auth.Text != "")
{
UserClass uc = new UserClass(tbx_User.Text, tbx_KeyWord.Text, tbx_Auth.Text);
dt.Add(uc);
}
else
{
MessageBox.Show("请输入完整","添加失败");
}
GridView1.ItemsSource = dt.Select();
}
private void btn_Remove_Click(object sender, RoutedEventArgs e)
{
string userid=tbx_User.Text;
UserClass uc = new UserClass(tbx_User.Text, tbx_KeyWord.Text, tbx_Auth.Text);
if (userid!="")
{
dt.Remove(uc.UserID);
}
else
{
MessageBox.Show("请选择要删除的用户", "操作失败");
}
GridView1.ItemsSource = dt.Select();
}
private void btn_Upate_Click(object sender, RoutedEventArgs e)
{
if (tbx_User.Text != "" && tbx_KeyWord.Text != "" && tbx_Auth.Text != "")
{
UserClass uc1 = new UserClass(tbx_User.Text, tbx_KeyWord.Text, tbx_Auth.Text);
dt.Update(uc1);
}
else
{
MessageBox.Show("请输入完整", "更新失败");
}
GridView1.ItemsSource = dt.Select();
}
private void btn_Select_Click(object sender, RoutedEventArgs e) { List<UserClass> ltt = new List<UserClass>(); int cbx = cbx_condition.SelectedIndex; SqlCommand cmd = new SqlCommand(); cmd.CommandType = CommandType.Text; datalist.Clear(); if (cbx==0) { //按用户名查询 cmd.CommandText = "SELECT * FROM tb_User WHERE UserID = @UserID"; cmd.Parameters.Add("@UserID", SqlDbType.VarChar).Value = tbx_forselect.Text; } else { //按权限查询 cmd.CommandText = "SELECT * FROM tb_User WHERE Auth = @Auth"; cmd.Parameters.Add("@Auth", SqlDbType.VarChar).Value = tbx_forselect.Text; } ltt = dt.ConditionSelect(cmd); if (lt.Count != 0) { for (int i = 0; i <= ltt.Count-1; i++) { datalist.Add(new UserClass(ltt[i].UserID,ltt[i].KeyWord,ltt[i].Auth )); } } // ListView1.ItemsSource = this.DataList; //xaml中已经绑定 } private void GridView1_SelectionChanged(object sender, SelectionChangedEventArgs e) { UserClass ul = this.GridView1.SelectedItem as UserClass; if (ul!=null) { tbx_User.Text = ul.UserID; tbx_KeyWord.Text = ul.KeyWord; tbx_Auth.Text = ul.Auth; } } private void ListView1_SelectionChanged(object sender, SelectionChangedEventArgs e) { UserClass ul = this.ListView1.SelectedItem as UserClass; if (ul != null) { tbx_User.Text = ul.UserID; tbx_KeyWord.Text = ul.KeyWord; tbx_Auth.Text = ul.Auth; } } }}
5. 数据绑定
从上面MainWindow.cs代码中可以看到，DataGrid控件和ListView控件只添加了一个SelectionChanged事件处理方法，用于将选择的条目显示在左上的文本框中，除此没有任何事件处理方法，其内容通过数据绑定来呈现。
绑定前先要指定数据源命名空间，前面在WPF命名空间中定义了ObservableCollection<T>泛型集合和List <T>泛型列表，本例可以在UI代码中看到Visual Studio自动添加了它们所在的命名空间和类的位置：
xmlns:local="clr-namespace:WPF"x:Class="WPF.MainWindow"
如果数据源定义不在内容控件所在的命名空间，就需要指定其所在的命名空间。如下：
xmlns:my="namespace:myNameSpace "
其中my为自定义标识，myNameSpace为数据源所在命名空间名称。接着需要在MainWindow类中定义资源：
<MainWindow.Resoures>
<my:myClass x:Key="myData"/>
</MainWindow.Resoures>
myClass为数据源所在命名空间中的类名，这样内容控件就可以绑定到myData上，如后面的LT用myData.LT替换即可。
先来看DataGrid控件数据的绑定，DataGrid控件派生自List类，因此需要为其指定ItemsSource，这里将其绑定到LT上，LT是在MainWindow类中定义的泛型列表List<UserClass>数据集合,RelativeSource用来指定绑定源相对于绑定目标的位置，获取或设置绑定源。这里的绑定实际上是用“数据绑定”向导实现的，不需要手工添加代码。
ItemsSource="{Binding LT, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type local:MainWindow}}}"
再来看ListView控件，ListView控件派生自ListBox类，它可以显示多列数据。经尝试不能将其绑定到List<UserClass>数据源，但可以绑定到ObservableCollection<UserClass>数据源上。首先指定ItemsResource数据源，方法如前使用向导实现。代码如下：
ItemsSource="{Binding DataList, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type local:MainWindow}}}"
接着添加要显示的数据列，表中数据共有3列，这里只显示2列，列名为UserID和Auth，并为列指定数据源路径DisplayMemberBinding，UserID和Auth是ItemsSource数据源DataList下的数据路径。
<GridViewColumn Header="UserID" Width="230" DisplayMemberBinding="{Binding UserID}"/>
<GridViewColumn Header="Auth" Width="230" DisplayMemberBinding="{Binding Auth}"/>
至此，DataGrid控件和ListView控件的数据绑定已经完成。通常文本框也可以通过数据绑定来显示数据，但左上文本框的数据源可能是DataGrid控件或ListView控件，WPF不能实现一对多的绑定。
LeiZhanfang
2016-02-14