如何在C#中使用HttpClient读取webapi响应

Question

我对webapi相当陌生，已经开发了一个小型webapi，它有一些操作并返回我的自定义类Response。

public class Response
{
    bool IsSuccess=false;
    string Message;
    object ResponseData;

    public Response(bool status, string message, object data)
    {
        IsSuccess = status;
        Message = message;
        ResponseData = data;
    }
}

[RoutePrefix("api/customer")]
public class CustomerController : ApiController
{
    static readonly ICustomerRepository repository = new CustomerRepository();

    [HttpGet, Route("GetAll")]
    public Response GetAllCustomers()
    {
        return new Response(true, "SUCCESS", repository.GetAll());
    }

    [HttpGet, Route("GetByID/{customerID}")]
    public Response GetCustomer(string customerID)
    {
        Customer customer = repository.Get(customerID);
        if (customer == null)
        {
            throw new HttpResponseException(HttpStatusCode.NotFound);
        }
        return new Response(true, "SUCCESS", customer);
        //return Request.CreateResponse(HttpStatusCode.OK, response);
    }

    [HttpGet, Route("GetByCountryName/{country}")]
    public IEnumerable<Customer> GetCustomersByCountry(string country)
    {
        return repository.GetAll().Where(
            c => string.Equals(c.Country, country, StringComparison.OrdinalIgnoreCase));
    }
}

现在我遇到的困难是，我不知道如何读取从webapi操作返回的响应数据，并从我的响应类中提取json。在获得json之后，如何将该json 发送到customer类。

这就是我调用webapi函数的方式:

private void btnLoad_Click(object sender, EventArgs e)
{
    HttpClient client = new HttpClient();
    client.BaseAddress = new Uri("http://localhost:8010/");
    // Add an Accept header for JSON format.  
    //client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
    // List all Names.  
    HttpResponseMessage response = client.GetAsync("api/customer/GetAll").Result;  // Blocking call!  
    if (response.IsSuccessStatusCode)
    {
        Console.WriteLine("Request Message Information:- \n\n" + response.RequestMessage + "\n");
        Console.WriteLine("Response Message Header \n\n" + response.Content.Headers + "\n");
    }
    else
    {
        Console.WriteLine("{0} ({1})", (int)response.StatusCode, response.ReasonPhrase);
    }
    Console.ReadLine();   
}

null

1）如何在客户端获取webapi返回的响应类

2）如何从响应类中提取json

3）如何在客户端将json反序列化为customer类

谢谢

我使用了这段代码，但仍然得到一个错误。

    var baseAddress = "http://localhost:8010/api/customer/GetAll";
    using (var client = new HttpClient())
    {
        using (var response =  client.GetAsync(baseAddress).Result)
        {
            if (response.IsSuccessStatusCode)
            {
                var customerJsonString = await response.Content.ReadAsStringAsync();
                var cust = JsonConvert.DeserializeObject<Response>(customerJsonString);
            }
            else
            {
                Console.WriteLine("{0} ({1})", (int)response.StatusCode, response.ReasonPhrase);
            }
        }
    }

null

newtonSoft.json.dll中发生类型为“newtonSoft.json.JsonSerializationException"的异常，但未在用户代码中处理

附加信息:无法将当前JSON对象（例如name:value}）反序列化为类型“webapiclient.response'，因为该类型需要JSON数组（例如[1，2，3])才能正确反序列化。

为什么响应会导致此错误？

Answer 1

也可以在同一呼叫上进行转换

  TResponse responseobject = response.Content.ReadAsAsync<TResponse>().Result;
            responseJson += "hostResponse: " + JsonParser.ConvertToJson(responseobject);
            //_logger.Debug($"responseJson : {responseJson}", correlationId);

Answer 2

在客户端上，包括对内容的读取:

    HttpResponseMessage response = client.GetAsync("api/customer/GetAll").Result;  // Blocking call!  
    if (response.IsSuccessStatusCode)
    {
        Console.WriteLine("Request Message Information:- \n\n" + response.RequestMessage + "\n");
        Console.WriteLine("Response Message Header \n\n" + response.Content.Headers + "\n");
        // Get the response
        var customerJsonString = await response.Content.ReadAsStringAsync();
        Console.WriteLine("Your response data is: " + customerJsonString);

        // Deserialise the data (include the Newtonsoft JSON Nuget package if you don't already have it)
        var deserialized = JsonConvert.DeserializeObject<IEnumerable<Customer>>(custome‌​rJsonString);
        // Do something with it
    }

更改WebApi，不使用响应类，而是使用 的 。使用 响应类。

您的WebAPI应该只需要:

[HttpGet, Route("GetAll")]
public IEnumerable<Customer> GetAllCustomers()
{
    var allCustomers = repository.GetAll();
    // Set a breakpoint on the line below to confirm
    // you are getting data back from your repository.
    return allCustomers;
}

根据注释中的讨论添加了泛型响应类的代码，但我仍然建议您不要这样做，并避免调用您的类响应。您应该返回HTTP状态代码，而不是您自己的状态代码。一个200 Ok，一个401未经授权，等等。这篇文章还介绍了如何返回HTTP状态代码。

    public class Response<T>
    {
        public bool IsSuccess { get; set; }
        public string Message { get; set; }
        public IEnumerable<T> ResponseData { get; set; }

        public Response(bool status, string message, IEnumerable<T> data)
        {
            IsSuccess = status;
            Message = message;
            ResponseData = data;
        }
    }