如何在 C# 中使用 HttpClient 读取 webapi 响应

我开发了一个小型 webapi，它有一些操作并返回我的自定义类，名为Response.

The Response class

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

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

我的带有操作的 webapi

[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));
    }
}

现在我陷入困境的是，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。得到 json 后我怎么能deserialize该 json 到客户类。

这是我调用 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();   
}

问题

1. 如何获取webapi在客户端返回的响应类

2. 如何从响应类中提取 json

3. 如何在客户端将json反序列化为客户类

我使用这段代码但仍然收到错误。

    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);
            }
        }
    }

错误是：

Newtonsoft.Json.dll 中发生“Newtonsoft.Json.JsonSerializationException”类型的异常，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？

在客户端上，包括内容的读取：

    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
    }

更改您的 WebApi 不使用您的 Response 类，而是使用IEnumerable of Customer。使用HttpResponseMessage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;
}

根据评论中的讨论添加了通用响应类的代码，尽管我仍然建议您不要这样做并避免调用您的类 Response。你应该返回HTTP 状态代码 http://en.wikipedia.org/wiki/List_of_HTTP_status_codes而不是你自己的。 200 Ok，401 Unauthorized，等等。这个帖子 https://stackoverflow.com/questions/10655350/returning-http-status-code-from-web-api-controller关于如何返回 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;
        }
    }