我想用依赖注入创建一个类的对象。如果我手动设置参数,则会出现异常Cannot access a disposed of the object.
。
此应用程序是带有 Dotnet 核心 3.1 的 Blazor wasm。我创建了一个应该连接到查询控制台的中间件。所以我有一个包含所有查询客户端的静态列表。如果缺少客户端,则会创建它。
在中间件中调用 Async:
public async Task InvokeAsync(HttpContext context,
IConfiguration configuration,
IInstanceControlRepository instanceControlRepository,
IServiceProvider serviceProvider)
{
_configuration = configuration;
_instanceControlRepository = instanceControlRepository;
long timestamp = new DateTimeOffset(DateTime.Now).ToUnixTimeSeconds();
var instances = _instanceControlRepository.GetAllInstances();
if (_time + 3 <= timestamp)
{
_time = timestamp;
// Remove
foreach(var client in TeamspeakInstanceQueryClients.ToList())
{
var cl = instances.ToList().Find(el => el.Id == client.Instance.Id);
if(cl == null)
{
client.Dispose();
TeamspeakInstanceQueryClients.RemoveAll(el => el.Instance.Equals(client.Instance));
}
}
// Create & Update
foreach (var instance in instances)
{
var queryClient = TeamspeakInstanceQueryClients.Find(el => el.Instance.Id == instance.Id);
if(queryClient == null)
{
//var test = ActivatorUtilities.CreateInstance<ApplicationDbContext>(serviceProvider);
//var dbContext = serviceProvider.GetService<ApplicationDbContext>();
//queryClient = new TeamspeakInstanceQueryClient(new InstancesControlRepository(ActivatorUtilities.CreateInstance<ApplicationDbContext>(serviceProvider)));
queryClient = new TeamspeakInstanceQueryClient(serviceProvider);
_ = queryClient.Connect(instance);
TeamspeakInstanceQueryClients.Add(queryClient);
}
else
{
_ = queryClient.CheckInstanceData(instance);
}
}
}
await _next(context);
}
TeamspeakInstanceQueryClient.cs
public partial class TeamspeakInstanceQueryClient : ITeamspeakInstanceQueryClient
{
private IInstanceControlRepository _instanceControlRepository;
private const short MAX_RETRYS = 3;
private const short TIME_TO_RETRY = 10;
private EventHandler OnConnected;
public Instance Instance { get; internal set; }
public TeamSpeakClient Client { get; internal set; }
public bool IsSelected { get; internal set; }
private short _connectionTrys = 0;
public TeamspeakInstanceQueryClient(IServiceProvider serviceProvider)
{
_instanceControlRepository = new InstancesControlRepository(ActivatorUtilities.CreateInstance<ApplicationDbContext>(serviceProvider));
Init();
}
}
InstancesControlRepository.cs
public class InstancesControlRepository : IInstanceControlRepository
{
private readonly ApplicationDbContext _applicationDbContext;
public InstancesControlRepository(ApplicationDbContext applicationDbContext)
{
_applicationDbContext = applicationDbContext;
}
}
启动文件
public void ConfigureServices(IServiceCollection services)
{
services.AddDbContext<ApplicationDbContext>(option =>
option.UseMySql(
Configuration.GetConnectionString("DefaultConnection"),
mySqlOptions => mySqlOptions.ServerVersion(new System.Version(10, 4, 13), ServerType.MariaDb)
)
);
services.AddScoped<IInstanceControlRepository, InstancesControlRepository>();
services.AddScoped<IServerQueryRepository, ServerQueryRepository>();
Cannot access a disposed of the object. Object name: 'IServiceProvider'.
似乎实例IServiceProvider
是一个作用域,它在作用域结束时被处理(在我假设的请求结束时)。您可以尝试为您定义单例工厂TeamspeakInstanceQueryClient
并使用它:
class ClientFactory
{
private IServiceProvider _sp { get; set; }
private IServiceScope _scope { get; set; }
public MyClass(IServiceProvider sp)
{
_sp = sp;
_scope = sp.CreateScope();
}
public TeamspeakInstanceQueryClient Create() => new TeamspeakInstanceQueryClient(_scope.ServiceProvider);
}
// register it as singleton
services.AddSingleton<ClientFactory>();
并将其用于InvokeAsync
:
var factory = serviceProvider.GetRequiredService<ClientFactory>();
queryClient = factory.Create();
PS 此代码可以大大改进,仅用于演示目的。
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