1. 在Startup.cs文件中的ConfigureServices方法中添加以下代码：

services.AddScoped();

2. 在App.razor文件中添加以下代码：

@using Microsoft.AspNetCore.Components.Routing
@using Microsoft.AspNetCore.Components.WebAssembly.Authentication
@using Microsoft.AspNetCore.Components.WebAssembly.Hosting
@using Microsoft.Extensions.DependencyInjection
@using System.Net.Http
@namespace MyNamespace.Client

    
        
            
                @{
                    var returnUrl = $"{routeData.Page?.FullPath ?? "/"}{routeData.QueryString}";
                    var returnUrlWithFragment = $"{returnUrl}#{routeData.Fragment}";
                }
                
            
            
                

                    Loading...
                
            
            
                @if (routeData.PageType == null)
                {
                    
Sorry, there's nothing at this address.
                }
                else
                {
                    
                }
            
        
    
    
        
Sorry, there's nothing at this address.
    

注意：在添加代码后，需要重启应用程序才能使更改生效。