在 C# 中通过 POST 发送 JSON 并接收返回的 JSON？

Question

这是我第一次在我的任何应用程序中使用 JSON 以及 System.Net 和 WebRequest。我的应用程序应该向身份验证服务器发送一个类似于下面的 JSON 有效负载：

{
  "agent": {                             
    "name": "Agent Name",                
    "version": 1                                                          
  },
  "username": "Username",                                   
  "password": "User Password",
  "token": "xxxxxx"
}

为了创建这个有效载荷，我使用了JSON.NET 库。我如何将此数据发送到身份验证服务器并接收其 JSON 响应？这是我在一些示例中看到的，但没有 JSON 内容：

var http = (HttpWebRequest)WebRequest.Create(new Uri(baseUrl));
http.Accept = "application/json";
http.ContentType = "application/json";
http.Method = "POST";

string parsedContent = "Parsed JSON Content needs to go here";
ASCIIEncoding encoding = new ASCIIEncoding();
Byte[] bytes = encoding.GetBytes(parsedContent);

Stream newStream = http.GetRequestStream();
newStream.Write(bytes, 0, bytes.Length);
newStream.Close();

var response = http.GetResponse();

var stream = response.GetResponseStream();
var sr = new StreamReader(stream);
var content = sr.ReadToEnd();

但是，与我过去使用过的其他语言相比，这似乎是很多代码。我这样做正确吗？以及如何获取 JSON 响应以便进行解析？

谢谢，精英。

更新代码

// Send the POST Request to the Authentication Server
// Error Here
string json = await Task.Run(() => JsonConvert.SerializeObject(createLoginPayload(usernameTextBox.Text, password)));
var httpContent = new StringContent(json, Encoding.UTF8, "application/json");
using (var httpClient = new HttpClient())
{
    // Error here
    var httpResponse = await httpClient.PostAsync("URL HERE", httpContent);
    if (httpResponse.Content != null)
    {
        // Error Here
        var responseContent = await httpResponse.Content.ReadAsStringAsync();
    }
}

Answer 1

我发现自己使用HttpClient 库来查询 RESTful API，因为代码非常简单且完全异步。要发送此 JSON 有效负载：

{
  "agent": {                             
    "name": "Agent Name",                
    "version": 1                                                          
  },
  "username": "Username",                                   
  "password": "User Password",
  "token": "xxxxxx"
}

有两个类代表您发布的 JSON 结构，可能如下所示：

public class Credentials
{
    public Agent Agent { get; set; }
    
    public string Username { get; set; }
    
    public string Password { get; set; }
    
    public string Token { get; set; }
}

public class Agent
{
    public string Name { get; set; }
    
    public int Version { get; set; }
}

您可以使用这样的方法来执行您的 POST 请求：

var payload = new Credentials { 
    Agent = new Agent { 
        Name = "Agent Name",
        Version = 1 
    },
    Username = "Username",
    Password = "User Password",
    Token = "xxxxx"
};

// Serialize our concrete class into a JSON String
var stringPayload = JsonConvert.SerializeObject(payload);

// Wrap our JSON inside a StringContent which then can be used by the HttpClient class
var httpContent = new StringContent(stringPayload, Encoding.UTF8, "application/json");

var httpClient = new HttpClient()
    
// Do the actual request and await the response
var httpResponse = await httpClient.PostAsync("http://localhost/api/path", httpContent);

// If the response contains content we want to read it!
if (httpResponse.Content != null) {
    var responseContent = await httpResponse.Content.ReadAsStringAsync();
    
    // From here on you could deserialize the ResponseContent back again to a concrete C# type using Json.Net
}

Answer 2

使用 JSON.NET NuGet 包和匿名类型，您可以简化其他发帖人的建议：

// ...

string payload = JsonConvert.SerializeObject(new
{
    agent = new
    {
        name    = "Agent Name",
        version = 1,
    },

    username = "username",
    password = "password",
    token    = "xxxxx",
});

var client = new HttpClient();
var content = new StringContent(payload, Encoding.UTF8, "application/json");

HttpResponseMessage response = await client.PostAsync(uri, content);

// ...

Answer 3

您可以使用JObject 的组合来构建您的HttpContent 来避免和JProperty，然后在构建StringContent 时调用ToString()：

        /*{
          "agent": {                             
            "name": "Agent Name",                
            "version": 1                                                          
          },
          "username": "Username",                                   
          "password": "User Password",
          "token": "xxxxxx"
        }*/

        JObject payLoad = new JObject(
            new JProperty("agent", 
                new JObject(
                    new JProperty("name", "Agent Name"),
                    new JProperty("version", 1)
                    ),
                new JProperty("username", "Username"),
                new JProperty("password", "User Password"),
                new JProperty("token", "xxxxxx")    
                )
            );

        using (HttpClient client = new HttpClient())
        {
            var httpContent = new StringContent(payLoad.ToString(), Encoding.UTF8, "application/json");

            using (HttpResponseMessage response = await client.PostAsync(requestUri, httpContent))
            {
                response.EnsureSuccessStatusCode();
                string responseBody = await response.Content.ReadAsStringAsync();
                return JObject.Parse(responseBody);
            }
        }

Answer 4

您还可以使用 HttpClient() 中提供的 PostAsJsonAsync() 方法

var requestObj= JsonConvert.SerializeObject(obj);
HttpResponseMessage response = await client.PostAsJsonAsync($"endpoint",requestObj);