Flurl4.0 应用handler

https://github.com/tmenier/Flurl/issues/346

handler定义:

public class PollyHandler : DelegatingHandler
{
    private readonly IAsyncPolicy<HttpResponseMessage> _policy;

    public PollyHandler(IAsyncPolicy<HttpResponseMessage> policy) {
        _policy = policy;
    }

    protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken) {
        return _policy.ExecuteAsync(ct => base.SendAsync(request, ct), cancellationToken);
    }
}

配置

var policy = Policy
    .Handle<HttpRequestException>()
    .OrResult<HttpResponseMessage>(r => !r.IsSuccessStatusCode)
    .RetryAsync(5);
FlurlHttp.Clients.WithDefaults(clientBuilder => clientBuilder.AddMiddleware(() => new PollyHandler (policy)));