使用DbContext时无法分隔代码

public interface IRepository<TEntity> where TEntity : class
{
    IEnumerable<TEntity> GetAll();
    TEntity GetById(int id);
    void Add(TEntity entity);
    void Update(TEntity entity);
    void Delete(int id);
}

public class Repository<TEntity> : IRepository<TEntity> where TEntity : class
{
    private readonly DbContext _context;
    private readonly DbSet<TEntity> _entities;

    public Repository(DbContext context)
    {
        _context = context;
        _entities = context.Set<TEntity>();
    }

    public IEnumerable<TEntity> GetAll() => _entities.ToList();
    public TEntity GetById(int id) => _entities.Find(id);
    public void Add(TEntity entity) => _entities.Add(entity);
    public void Update(TEntity entity) => _entities.Update(entity);
    public void Delete(int id)
    {
        var entity = _entities.Find(id);
        if (entity != null)
        {
            _entities.Remove(entity);
        }
    }
}

public void ConfigureServices(IServiceCollection services)
{
    services.AddDbContext<ApplicationDbContext>(options =>
        options.UseSqlServer(Configuration.GetConnectionString("DefaultConnection")));

    services.AddScoped(typeof(IRepository<>), typeof(Repository<>));
}

public class UserService
{
    private readonly IRepository<User> _userRepository;

    public UserService(IRepository<User> userRepository)
    {
        _userRepository = userRepository;
    }

    public User GetUserById(int id) => _userRepository.GetById(id);
    // 其他业务逻辑...
}