WPF使用MVVMLight的ViewModel 访问控件的属性方法事件以及多页面传递信息

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<Window x:Class="MVVMLightDemo.View.MainView"
        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:MVVMLightDemo.View" xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity"
        mc:Ignorable="d"
        Title="MainView" Height="450" Width="800">
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="100"/>
            <ColumnDefinition Width="*"/>
        </Grid.ColumnDefinitions>
        <StackPanel Grid.Column ="0">
            <Button Content="UI1" Command="{Binding UI1Command}" />
            <Button Content="UI2" Command="{Binding UI2Command}"/>
        </StackPanel>
        <GridSplitter Grid.Row="0" Grid.Column="1" Width="5" HorizontalAlignment="Left" VerticalAlignment="Stretch" Background="#FFC1BDC5" Grid.RowSpan="2" />
        <Grid Grid.Column="1">
            <Grid.RowDefinitions>
                <RowDefinition Height="*"/>
                <RowDefinition Height="100"/>
            </Grid.RowDefinitions>
            <GridSplitter Height="5" Grid.Row="0" Grid.Column="1" Background="#FFC1BDC5" HorizontalAlignment="Stretch" VerticalAlignment="Bottom"/>
            <Border  Grid.Row ="0"  BorderBrush="Gray" BorderThickness="1" >
                <ContentPresenter  Content="{Binding Content}" Margin="5,0"/>
                <!--使用内容呈现器来切换界面-->
            </Border>
            <Border Grid.Row ="1"  BorderBrush="Gray" BorderThickness="1">
                <TextBox x:Name="LogTextBox" Text="{Binding TextLog}" VerticalScrollBarVisibility="Auto" HorizontalScrollBarVisibility="Auto" >
                    <i:Interaction.Triggers>
                        <i:EventTrigger EventName="Loaded">
                            <i:InvokeCommandAction Command="{Binding Path=TextBoxLoadedCommand}"
                                   CommandParameter="{Binding ElementName=LogTextBox}">
                            </i:InvokeCommandAction>
                        </i:EventTrigger>
                    </i:Interaction.Triggers>
                </TextBox>
            </Border>
        </Grid>
    </Grid>
</Window>

MainView.xaml

<UserControl x:Class="MVVMLightDemo.View.UI1View"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
             xmlns:local="clr-namespace:MVVMLightDemo.View"
             mc:Ignorable="d" 
             d:DesignHeight="100" d:DesignWidth="200">
        <Button Content="UI1向日志界面传递信息" Command="{Binding BtnCommand}" HorizontalAlignment="Center" VerticalAlignment="Center"/>
    </Grid>
</UserControl>

UI1View.xaml

UI1界面里只有一个Button并绑定一个命令，单击这个按键会向日志里打印文本，UI2和UI1类似

<UserControl x:Class="MVVMLightDemo.View.UI2View"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
             xmlns:local="clr-namespace:MVVMLightDemo.View"
             mc:Ignorable="d" 
             d:DesignHeight="100" d:DesignWidth="200">
        <Button Content="UI2向日志界面传递信息" Command="{Binding BtnCommand}" HorizontalAlignment="Left" VerticalAlignment="Top"/>
    </Grid>
</UserControl>

UI2View.xaml

三个UI界面对应的三个ViewModel分别如下

using GalaSoft.MvvmLight;
using GalaSoft.MvvmLight.Command;
using GalaSoft.MvvmLight.Messaging;
using MVVMLightDemo.View;
using System;
using System.Windows.Controls;
namespace MVVMLightDemo.ViewModel
    /// <summary>
    /// This class contains properties that the main View can data bind to.
    /// <para>
    /// Use the <strong>mvvminpc</strong> snippet to add bindable properties to this ViewModel.
    /// </para>
    /// <para>
    /// You can also use Blend to data bind with the tool's support.
    /// </para>
    /// <para>
    /// See http://www.galasoft.ch/mvvm
    /// </para>
    /// </summary>
    public class MainViewModel : ViewModelBase
        /// <summary>
        /// Initializes a new instance of the MainViewModel class.
        /// </summary>
        #region 成员
        TextBox TextBoxLog = new TextBox();
        public UserControl UserUI1 = new UI1View();
        public UserControl UserUI2 = new UI2View();
        #endregion
        #region 构造方法
        public MainViewModel()
            ///Messenger：信使
            ///Recipient：收件人
            Messenger.Default.Register<string>(this, "Log", msg =>  //注册Log消息 其内容是向日志文本追加文本
                TextLog += msg;
        #endregion
        #region 绑定属性
        //主页面的内容呈现器
        private UserControl _content;
        public UserControl Content
            get { return _content; }
            set { _content = value;RaisePropertyChanged(() => Content);}
        //文本日志
        private string textlog;
        public string TextLog
            get { return textlog; }
            set { textlog = value; RaisePropertyChanged(() => TextLog); }
        #endregion
        #region Button UI1命令
        private RelayCommand ui1Command;
        public RelayCommand UI1Command
                if (ui1Command == null)
                    ui1Command = new RelayCommand(() => ExcuteUI1Command());
                return ui1Command;
            set { ui1Command = value; }
        private void ExcuteUI1Command()
            Content = UserUI1;
        #endregion
        #region Button UI2命令
        private RelayCommand ui2Command;
        public RelayCommand UI2Command
                if (ui2Command == null)
                    ui2Command = new RelayCommand(() => ExcuteUI2Command());
                return ui2Command;
            set { ui2Command = value; }
        private void ExcuteUI2Command()
            Content = UserUI2;
        #endregion
        #region TextBox 
        private RelayCommand<TextBox> textBoxLoadedCommand;
        public RelayCommand<TextBox> TextBoxLoadedCommand
                if (textBoxLoadedCommand == null)
                    textBoxLoadedCommand = new RelayCommand<TextBox>((p) => ExecuteTextBoxLoadedCommandCommand(p));
                return textBoxLoadedCommand;
            set { textBoxLoadedCommand = value; }
        private void ExecuteTextBoxLoadedCommandCommand(TextBox p)
            TextBoxLog = (System.Windows.Controls.TextBox)p;//TextBox加载的时候把自身最为参数传递到ViewModel里来，有了这个参数就可以在ViewModel中使用该控件的属性方法以及事件
            TextBoxLog.IsReadOnly = true;//设为只读（使用控件的属性）
            TextBoxLog.TextChanged += TextBoxLog_TextChanged;//添加文本发生改变的事件（使用控件的事件）
        private void TextBoxLog_TextChanged(object sender, TextChangedEventArgs e)
            TextBoxLog.ScrollToEnd();//文本发生改变的时候让文本自动滚到底部（使用控件的方法）
        #endregion
MainViewModel.cs
                <TextBox x:Name="LogTextBox" Text="{Binding TextLog}" VerticalScrollBarVisibility="Auto" HorizontalScrollBarVisibility="Auto" >
                    <i:Interaction.Triggers>
                        <i:EventTrigger EventName="Loaded">
                            <i:InvokeCommandAction Command="{Binding Path=TextBoxLoadedCommand}"
                                   CommandParameter="{Binding ElementName=LogTextBox}">
                            </i:InvokeCommandAction>
                        </i:EventTrigger>
                    </i:Interaction.Triggers>
                </TextBox>
在MainView.xaml中TextBox绑定了加载事件Loaded,这里绑定的事件命令的同时还传递了一个TextBox自身参数LogTextBox,这个参数会带到MainViewModel.cs文件中去




    

        private RelayCommand<TextBox> textBoxLoadedCommand;
        public RelayCommand<TextBox> TextBoxLoadedCommand
                if (textBoxLoadedCommand == null)
                    textBoxLoadedCommand = new RelayCommand<TextBox>((p) => ExecuteTextBoxLoadedCommandCommand(p));
                return textBoxLoadedCommand;
            set { textBoxLoadedCommand = value; }
        private void ExecuteTextBoxLoadedCommandCommand(TextBox p)
            TextBoxLog = (System.Windows.Controls.TextBox)p;//TextBox加载的时候把自身最为参数传递到ViewModel里来，有了这个参数就可以在ViewModel中使用该控件的属性方法以及事件
            TextBoxLog.IsReadOnly = true;//设为只读（使用控件的属性）
            TextBoxLog.TextChanged += TextBoxLog_TextChanged;//添加文本发生改变的事件（使用控件的事件）
        private void TextBoxLog_TextChanged(object sender, TextChangedEventArgs e)
            TextBoxLog.ScrollToEnd();//文本发生改变的时候让文本自动滚到底部（使用控件的方法）
在MainViewModel.cs中操作该参数就像在后台文件中操作MainView.xaml.cs中操作LogTextBox是一样的，有了这个参数就可以在MainViewModel.cs中任意位置使用该控件的属性和方法了，如果想使用控件的事件直接在加载命令中注册即可。
在MainViewModel.cs构造方法中注册了一个信使名字叫做Log
        public MainViewModel()
            ///Messenger：信使
            ///Recipient：收件人
            Messenger.Default.Register<string>(this, "Log", msg =>  //注册Log消息 其内容是向日志文本追加文本
                TextLog += msg;
注册了这个信使后，就可以在其他页面的ViewModel中直接发送消息，发送的消息除了是string类型还可以是自定义类类型
using GalaSoft.MvvmLight;
using GalaSoft.MvvmLight.Command;
using GalaSoft.MvvmLight.Messaging;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace MVVMLightDemo.ViewModel
    public class UI1ViewModel : ViewModelBase
        private RelayCommand btnCommand;
        public RelayCommand BtnCommand
                if (btnCommand == null)
                    btnCommand = new RelayCommand(() => ExcuteBtnCommand());
                return btnCommand;
            set { btnCommand = value; }
        private void ExcuteBtnCommand()
            Messenger.Default.Send<string>("我是UI1！\n", "Log");//向Log发送消息 （追加文本）
UI1ViewModel.cs
using GalaSoft.MvvmLight;
using GalaSoft.MvvmLight.Command;
using GalaSoft.MvvmLight.Messaging;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace MVVMLightDemo.ViewModel
    public class UI2ViewModel : ViewModelBase
        private RelayCommand btnCommand;
        public RelayCommand BtnCommand
                if (btnCommand == null)
                    btnCommand = new RelayCommand(() => ExcuteBtnCommand());
                return btnCommand;
            set { btnCommand = value; }
        private void ExcuteBtnCommand()
            Messenger.Default.Send<string>("我是UI2！\n", "Log");//向Log发送消息 （追加文本）
UI2ViewModel.cs
 源码下载地址lizhiqiang0204/MVVMLightDemo (github.com)