C#_WPF_MVVM_实现登录功能

创建Model（模型）
首先定义一个LoginModel模型来表示登录信息。

namespace Login.Model
{
 public class LoginModel
 {
     public string Username { get; set; }
     public string Password { get; set; }
 }
}

创建ViewModel（视图模型）
ViewModel作为View和Model之间的桥梁，包含用户输入的数据和命令绑定。

using System;
using System.ComponentModel;
using System.Windows.Input;
using Login.Command;
using Login.Model;

namespace Login.ViewModel
{
 public class LoginViewModel : INotifyPropertyChanged
 {

     private LoginModel loginModel;

     public String Username
     {
         get { return loginModel.Username; }
         set
         { 
             this.loginModel.Username = value;
             OnPropertyChanged(nameof(Username));
         }
     }

     public String Password
     { 
         get { return loginModel.Password; }
         set
         { 
             this.loginModel.Password = value;
             OnPropertyChanged("Password");
         }
     }

     public ICommand LoginCommand { get; private set; }

     public LoginViewModel()
     {
         loginModel = new LoginModel();
         LoginCommand = new RelayCommand(Login, CanLogin);
     }

     private void Login(object parameter)
     {
         // 在这里添加登入逻辑
         if (CanLogin(null))
         {
             Console.WriteLine($"登录成功：用户名={Username}, 密码={Password}");
         }
     }

     private bool CanLogin(object parameter)
     {
         // 在这里添加验证逻辑
         return !string.IsNullOrEmpty(Username) && !string.IsNullOrEmpty(Password);
     }

     public event PropertyChangedEventHandler PropertyChanged;
     protected virtual void OnPropertyChanged(string propertyName)
     {
         PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
     }
 }
}

创建View（视图）
接下来创建XAML界面用于用户输入和触发登录命令。

<Window x:Class="Login.MainWindow"
     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"
     xmlns:local="clr-namespace:Login"
     mc:Ignorable="d"
     Title="MainWindow" Height="450" Width="800">
 <Grid>
     <StackPanel Margin="20">
         <Label Content="Username:"/>
         <TextBox Text="{Binding Username, UpdateSourceTrigger=PropertyChanged}" Margin="0,5"/>
         <Label Content="Password:"/>
         <TextBox Text="{Binding Password, UpdateSourceTrigger=PropertyChanged}" Margin="0,5"/>
         <Button Content="Login" Command="{Binding LoginCommand}" Width="100" Height="30" Margin="0,15"/>
     </StackPanel>
 </Grid>
</Window>

4.创建RelayCommand
RelayCommand是一个实现了ICommand接口的类，用于绑定View中的命令到ViewModel的命令处理方法

using System;
using System.Windows.Input;

namespace Login.Command
{
 public class RelayCommand : ICommand
 {
     private readonly Action<object> _execute;
     private readonly Func<object, bool> _canExecute;

     public RelayCommand(Action<object> execute, Func<object, bool> canExecute = null)
     {
         _execute = execute ?? throw new ArgumentNullException(nameof(execute));
         _canExecute = canExecute;
     }

     public event EventHandler CanExecuteChanged
     {
         add { CommandManager.RequerySuggested += value; }
         remove { CommandManager.RequerySuggested -= value; }
     }

     public bool CanExecute(object parameter)
     {
         return _canExecute == null || _canExecute(parameter);
     }

     public void Execute(object parameter)
     {
         _execute(parameter);
     }
 }
}

5.绑定DataContext
建立视图（UI）与视图模型（ViewModel）之间的数据绑定关系

using System.Windows.Data;
using Login.ViewModel;

namespace Login
{
 /// <summary>
 /// MainWindow.xaml 的交互逻辑
 /// </summary>
 public partial class MainWindow : Window
 {
     public MainWindow()
     {
         InitializeComponent();
         DataContext = new LoginViewModel();
     }
 }
}