WPF写一个用户选择控件，从下拉框中选择用户，每一个用户都显示出来

下面是一个简单的WPF用户选择控件的示例代码，其中使用了ComboBox和ListBox控件：

XAML代码：

<UserControl x:Class="UserSelectorControl.UserSelector"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
             mc:Ignorable="d"
             d:DesignHeight="300" d:DesignWidth="300">
    <Grid>
        <ComboBox x:Name="UserComboBox" SelectionChanged="UserComboBox_SelectionChanged">
            <ComboBox.ItemTemplate>
                <DataTemplate>
                    <TextBlock Text="{Binding UserName}" />
                </DataTemplate>
            </ComboBox.ItemTemplate>
        </ComboBox>
        <ListBox x:Name="SelectedUsersListBox" Grid.Row="1">
            <ListBox.ItemTemplate>
                <DataTemplate>
                    <TextBlock Text="{Binding UserName}" />
                </DataTemplate>
            </ListBox.ItemTemplate>
        </ListBox>
    </Grid>
</UserControl>

C#代码：

using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Windows;
using System.Windows.Controls;

namespace UserSelectorControl
{
    public partial class UserSelector : UserControl
    {
        public static readonly DependencyProperty UsersProperty =
            DependencyProperty.Register("Users", typeof(ObservableCollection<User>), typeof(UserSelector), new PropertyMetadata(null));

        public ObservableCollection<User> Users
        {
            get { return (ObservableCollection<User>)GetValue(UsersProperty); }
            set { SetValue(UsersProperty, value); }
        }

        public static readonly DependencyProperty SelectedUsersProperty =
            DependencyProperty.Register("SelectedUsers", typeof(ObservableCollection<User>), typeof(UserSelector), new PropertyMetadata(null));

        public ObservableCollection<User> SelectedUsers
        {
            get { return (ObservableCollection<User>)GetValue(SelectedUsersProperty); }
            set { SetValue(SelectedUsersProperty, value); }
        }

        public UserSelector()
        {
            InitializeComponent();
            Users = new ObservableCollection<User>();
            SelectedUsers = new ObservableCollection<User>();
        }

        private void UserComboBox_SelectionChanged(object sender, SelectionChangedEventArgs e)
        {
            if (UserComboBox.SelectedItem != null)
            {
                var user = (User)UserComboBox.SelectedItem;
                if (!SelectedUsers.Contains(user))
                {
                    SelectedUsers.Add(user);
                }
            }
        }
    }

    public class User
    {
        public string UserName { get; set; }
    }
}

在使用该控件时，需要为Users属性设置一个包含所有用户的ObservableCollection，例如：

<Window x:Class="UserSelectorControl.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:userSelector="clr-namespace:UserSelectorControl"
        Title="MainWindow" Height="450" Width="800">
    <Grid>
        <userSelector:UserSelector Users="{Binding AllUsers}" SelectedUsers="{Binding SelectedUsers}" />
    </Grid>
</Window>

其中，AllUsers和SelectedUsers都是在ViewModel中定义的ObservableCollection。