ContentView类定义了一个View类型的Content属性，它表示ContentView的内容。此属性由BindableProperty对象支持，这意味着它可以成为数据绑定的目标，并具有样式。
ContentView类本身提供的功能很少，但可用于创建自定义控件。创建自定义控件的过程是：

• 创建从ContentView类派生的类。
• 在自定义控件的代码隐藏文件中定义任何控件属性或事件。
• 定义自定义控件的UI。

有关更多信息，您可以查看官方文档：创建自定义控件。

注：

您也可以在这里查看示例ContentView Demos，它将帮助您了解如何使用ContentView创建自定义控件。虽然此示例是Xamarin表单的应用程序，但它也适用于MAUI。

我做了这样的事情，它的工作，但它是最好的做法，使用我不确定。
这里是页面：

<ContentPage    
    xmlns:viewmodel="clr-namespace:V7.UIS.MauiMobile.ViewModels"
    x:DataType="viewmodel:AboutViewModel"
    Title="About">
    <VerticalStackLayout>

        <controls:ItemBarcodeSearchView HttpClient="{Binding HttpClient}" />

        <Entry Text="Count" />
        <Button
            Grid.Row="1"
            Grid.Column="1"
            Text="Add"/>
    </VerticalStackLayout>
</ContentPage>

using V7.UIS.MauiMobile.Constants;

namespace V7.UIS.MauiMobile.ViewModels
{
    public class AboutViewModel : BaseViewModel
    {
        private readonly HttpClient _client;

        public const string ViewName = "AboutPage";

        public AboutViewModel(IHttpClientFactory factory)
        {
            Title = "About";
            _client = factory?.CreateClient(AppConstants.ApiName);
        }
        public HttpClient HttpClient => _client;
    }
}

下面是自定义控件：

using CommunityToolkit.Mvvm.Input;
using V7.BaseApplication.AppModels.Erp.Cards.Item.ItemBarcode.Queries;
using V7.BaseApplication.AppModels.Erp.Cards.Item.ItemBarcode.ViewModel;
using V7.UIS.MauiMobile.Helpers;
using V7.UIS.MauiMobile.Models;

namespace V7.UIS.MauiMobile.Controls.Views;

public partial class ItemBarcodeSearchView : ContentView
{
    public ItemBarcodeSearchView()
    {
        InitializeComponent();
        IsVisibleButtonGrid = "true";
        IsVisibleDetailGrid = "false";
    }

    public event EventHandler<ItemBarcodeDetail> BarcodeDetailsReady;

    #region PropertyDefinition 

    public static readonly BindableProperty BarcodeProperty =
        BindableProperty.Create(nameof(Barcode), typeof(string), typeof(ItemBarcodeSearchView));
    public static readonly BindableProperty ItemDescriptionProperty =
        BindableProperty.Create(nameof(ItemDescription), typeof(string), typeof(ItemBarcodeSearchView));
    public static readonly BindableProperty ItemUnitProperty =
        BindableProperty.Create(nameof(ItemUnit), typeof(string), typeof(ItemBarcodeSearchView));
    public static readonly BindableProperty ItemLotProperty =
        BindableProperty.Create(nameof(ItemLot), typeof(string), typeof(ItemBarcodeSearchView));
    public static readonly BindableProperty ItemSerialNumberProperty =
        BindableProperty.Create(nameof(ItemSerialNumber), typeof(string), typeof(ItemBarcodeSearchView));
    public static readonly BindableProperty QuantityProperty =
        BindableProperty.Create(nameof(Quantity), typeof(string), typeof(ItemBarcodeSearchView));
    public static readonly BindableProperty IsVisibleButtonGridProperty =
        BindableProperty.Create(nameof(IsVisibleButtonGrid), typeof(string), typeof(ItemBarcodeSearchView));
    public static readonly BindableProperty IsVisibleDetailGridProperty =
        BindableProperty.Create(nameof(IsVisibleDetailGrid), typeof(string), typeof(ItemBarcodeSearchView));
    public static readonly BindableProperty HttpClientProperty =
            BindableProperty.Create(nameof(HttpClient), typeof(HttpClient), typeof(ItemBarcodeSearchView));
    public HttpClient HttpClient
    {
        get => (HttpClient)GetValue(HttpClientProperty);
        set => SetValue(HttpClientProperty, value);
    }
    public string IsVisibleButtonGrid
    {
        get => (string)GetValue(IsVisibleButtonGridProperty);
        set => SetValue(IsVisibleButtonGridProperty, value);
    }
    public string IsVisibleDetailGrid
    {
        get => (string)GetValue(IsVisibleDetailGridProperty);
        set => SetValue(IsVisibleDetailGridProperty, value);
    }
    public string Barcode
    {
        get => (string)GetValue(BarcodeProperty);
        set => SetValue(BarcodeProperty, value);
    }
    public string ItemDescription
    {
        get => (string)GetValue(ItemDescriptionProperty);
        set => SetValue(ItemDescriptionProperty, value);
    }
    public string ItemUnit
    {
        get => (string)GetValue(ItemUnitProperty);
        set => SetValue(ItemUnitProperty, value);
    }
    public string ItemLot
    {
        get => (string)GetValue(ItemLotProperty);
        set => SetValue(ItemLotProperty, value);
    }
    public string ItemSerialNumber
    {
        get => (string)GetValue(ItemSerialNumberProperty);
        set => SetValue(ItemSerialNumberProperty, value);
    }
    public string Quantity
    {
        get => (string)GetValue(QuantityProperty);
        set => SetValue(QuantityProperty, value);
    }
    #endregion

    private void ShowView(object sender, EventArgs e)
    {
        IsVisibleButtonGrid = "false";
        IsVisibleDetailGrid = "true";
    }

    [RelayCommand]
    public void ClearFields()
    {
        Barcode = string.Empty;
        ItemDescription = string.Empty;
        ItemUnit = string.Empty;
        ItemLot = string.Empty;
        ItemSerialNumber = string.Empty;
        Quantity = string.Empty;
    }
    [RelayCommand]
    public async Task Search()
    {
        await FindItemDetails(Barcode, HttpClient);
    }

    public async Task FindItemDetails(string barcode, HttpClient client)
    {
        if (!string.IsNullOrEmpty(barcode))
        {
            GetBarcodeDetailQuery query = new()
            {
                Barcode = barcode
            };
            await client.GetDataFromApi<GetBarcodeDetailQuery, GetBarcodeDetailViewModel>("Cards/ItemBarcode/GetBarcodeDetail", query, FindBarcodeCallBack);
        }
        else
        {
            await Shell.Current.DisplayAlert("Hata", "Lütfen bir barkod giriniz.", "Ok");
        }
    }

    void FindBarcodeCallBack(GetBarcodeDetailViewModel vm)
    {
        ItemDescription = vm.Item.Description;
        ItemUnit = vm.ItemUnits.FirstOrDefault().ToString();
        ItemLot = vm.Lot.ToString();
        ItemSerialNumber = vm.SerialNumber.ToString();
        Quantity = "0";
    }

    private void SendBarcodeDetails(object sender, EventArgs e)
    {
        ItemBarcodeDetail itemBarcodeDetail = new()
        {
            Barcode = Barcode,
            ItemDescription = ItemDescription,
            ItemUnit = ItemUnit,
            ItemLot = ItemLot,
            ItemSerialNumber = ItemSerialNumber,
            Quantity = Quantity,
        };
        BarcodeDetailsReady?.Invoke(sender, itemBarcodeDetail);
        IsVisibleButtonGrid = "true";
        IsVisibleDetailGrid = "false";
    }
}