主要参考学习张善友大神的提示，使用Blazored.LocalStorage包本地cookie方式 

本文将以Server Side的方式介绍，WASM方式仅需修改少数代码即可完成移植，不再赘述。下文介绍的是基于Token的内网用户名/密码认证，出于登录演示机制的考虑，并不保证代码在安全逻辑层面是可靠的。不要使用未加改造的本文代码，使用在生产网络中！

1. Nuget安装Blazored.LocalStorage包。此包使用JS与客户端环境交互，保存/读取本地数据。

2. 注册认证和授权服务。

    1 //ConfigureServices
    2 services.AddAuthentication();
    3 services.AddAuthorization();
    4 services.AddControllers();
    5 services.AddHttpClient();
    6 services.AddBlazoredLocalStorage();
    7 //Configure
    8 app.UseAuthentication();
    9 app.UseAuthorization();
   10 app.UseEndpoints(endpoints => {
   11 //...
   12     endpoints.MapControllers();
   13 //...
   14 })

   　　

3. Data新建CurrentUser.cs

    1 using Blazored.LocalStorage;
    2 using System;
    3 using System.Collections.Generic;
    4 using System.Linq;
    5 using System.Threading.Tasks;
    6 
    7 namespace BlazorAuthoriation.Data
    8 {
    9     public class CurrentUser
   10     {
   11         static string LOCAL_STORAGE_KEY = "stweily";
   12         public static async Task<CurrentUser> Load(ILocalStorageService localStorage)
   13         {
   14             var s = await localStorage.GetItemAsync<string>(LOCAL_STORAGE_KEY);
   15             return FromStorageString(s);
   16         }
   17         public static CurrentUser FromStorageString(string s)
   18         {
   19             if (s == null)
   20                 return null;
   21             return new CurrentUser() { UserName= s };
   22             //return null;
   23         }
   24         public static async Task Remove(Blazored.LocalStorage.ILocalStorageService localStorage)
   25         {
   26             await localStorage.RemoveItemAsync(LOCAL_STORAGE_KEY);
   27         }
   28         public static async Task Login(Blazored.LocalStorage.ILocalStorageService localStorage,string name, string pwd)
   29         {
   30             await localStorage.SetItemAsync<string>(LOCAL_STORAGE_KEY, name);
   31         }
   32         public string UserName { set; get; }
   33     }
   34 }

    

4. 增加Login.razor

    1 @page "/login"
    2 @using BlazorAuthoriation.Data
    3 @inject NavigationManager nav
    4 @*@inject Blazored.SessionStorage.ISessionStorageService storage*@
    5 @inject Blazored.LocalStorage.ILocalStorageService storage
    6 
    7 @if (null == currUser)
    8 {
    9     <h3>
   10         账号：<input />
   11         密码：<input />
   12         <button @onclick="login">确定</button>
   13     </h3>
   14 }
   15 else
   16 {
   17     <h3>
   18         Welcome,<b> @currUser.UserName </b>!
   19         <button @onclick="logout">退出</button>
   20     </h3>
   21 }
   22 @code {
   23     [CascadingParameter]
   24     protected CurrentUser currUser { get; set; }
   25 
   26     [Parameter]
   27     public EventCallback<string> LoginEvents { get; set; }
   28     [Parameter]
   29     public EventCallback LogoutEvents { get; set; }
   30     private async Task RaiseLoginEvent()
   31     {
   32         if (LoginEvents.HasDelegate)
   33         {
   34             await LoginEvents.InvokeAsync(null);
   35             StateHasChanged();
   36         }
   37     }
   38     private async Task RaiseLogoutEvent()
   39     {
   40         if (LogoutEvents.HasDelegate)
   41         {
   42             await LogoutEvents.InvokeAsync(null);
   43             StateHasChanged();
   44         }
   45     }
   46 
   47     private async Task logout()
   48     {
   49         await CurrentUser.Remove(storage);
   50         await RaiseLogoutEvent();
   51         nav.NavigateTo("/");
   52     }
   53     private async void login()
   54     {
   55         await CurrentUser.Login(storage, "stweily", "123");
   56         await RaiseLoginEvent();
   57         nav.NavigateTo("/");
   58     } 
   59 }

    

5. 修改Mainlayout.razor

    1 @inherits LayoutComponentBase
    2 @inject NavigationManager nav
    3 @inject Blazored.LocalStorage.ILocalStorageService storage
    4 @using BlazorAuthoriation.Data
    5 @using BlazorAuthoriation.Pages
    6 
    7 <div class="sidebar">
    8     <NavMenu />
    9 </div>
   10 <CascadingValue Value="currUser">
   11     <div class="main">
   12         <div class="top-row px-4">
   13             @*<a href="https://docs.microsoft.com/aspnet/" target="_blank">About</a>*@
   14             <Login LoginEvents="(e)=>LoginEvent(e)" LogoutEvents="(e)=>LogoutEvent(e)" />
   15         </div>
   16         <div class="content px-4">
   17             @if (currUser == null)
   18             {
   19                 <h3>请登录以后再操作内容！！</h3>
   20             }
   21             else
   22                 @Body
   23         </div>
   24     </div>
   25 </CascadingValue>
   26 @code{
   27     /// <summary>
   28     /// 强制刷新标志
   29     /// </summary>
   30     private bool forceRender { get; set; } = false;
   31     private void LogoutEvent(object username)
   32     {
   33         //msg.Info($"See you later {(string)username}");
   34         //通过 LoginControl 组件回调 接收强制刷新消息
   35         //loginControl.ChildEvents.InvokeAsync("this is key");
   36         //currUser = null;
   37         forceRender = true;
   38     }
   39     private void LoginEvent(object username)
   40     {
   41         //msg.Info($"See you later {(string)username}");
   42         //通过 LoginControl 组件回调 接收强制刷新消息
   43         //loginControl.ChildEvents.InvokeAsync("this is key");
   44         //currUser = null;
   45         forceRender = true;
   46     }
   47 
   48     protected override async Task OnAfterRenderAsync(bool firstRender)
   49     {
   50         base.OnAfterRender(firstRender);
   51         if (firstRender || forceRender)
   52         {
   53             forceRender = false;
   54 
   55             currUser = await CurrentUser.Load(storage);
   56             if (null == currUser)
   57                 nav.NavigateTo("/Login");
   58             else
   59                 StateHasChanged();
   60         }
   61     }
   62     /// <summary>
   63     /// 有 CascadingValue 加持, 所有子组件可以通过 [CascadingParameter] 继承读取
   64     /// </summary>
   65     private CurrentUser currUser { get; set; }
   66 }