如何使用C#将JSON发布到服务器？

Question

这是我正在使用的代码:

// create a request
HttpWebRequest request = (HttpWebRequest)
WebRequest.Create(url); request.KeepAlive = false;
request.ProtocolVersion = HttpVersion.Version10;
request.Method = "POST";


// turn our request string into a byte stream
byte[] postBytes = Encoding.UTF8.GetBytes(json);

// this is important - make sure you specify type this way
request.ContentType = "application/json; charset=UTF-8";
request.Accept = "application/json";
request.ContentLength = postBytes.Length;
request.CookieContainer = Cookies;
request.UserAgent = currentUserAgent;
Stream requestStream = request.GetRequestStream();

// now send it
requestStream.Write(postBytes, 0, postBytes.Length);
requestStream.Close();

// grab te response and print it out to the console along with the status code
HttpWebResponse response = (HttpWebResponse)request.GetResponse();
string result;
using (StreamReader rdr = new StreamReader(response.GetResponseStream()))
{
    result = rdr.ReadToEnd();
}

return result;

当我运行它时,我总是得到500内部服务器错误.

我究竟做错了什么？

Answer 1

我这样做并且正在工作的方式是:

var httpWebRequest = (HttpWebRequest)WebRequest.Create("http://url");
httpWebRequest.ContentType = "application/json";
httpWebRequest.Method = "POST";

using (var streamWriter = new StreamWriter(httpWebRequest.GetRequestStream()))
{
    string json = "{\"user\":\"test\"," +
                  "\"password\":\"bla\"}";

    streamWriter.Write(json);
}

var httpResponse = (HttpWebResponse)httpWebRequest.GetResponse();
using (var streamReader = new StreamReader(httpResponse.GetResponseStream()))
{
    var result = streamReader.ReadToEnd();
}

我写了一个库来以更简单的方式执行这个任务,它在这里:https://github.com/ademargomes/JsonRequest

希望能帮助到你.

Answer 2

ADEMAR的溶液可以通过利用来改善JavaScriptSerializer的Serialize方法来提供该对象的JSON隐式转换.

此外,可以利用using语句的默认功能,以省略显式调用Flush和Close.

var httpWebRequest = (HttpWebRequest)WebRequest.Create("http://url");
httpWebRequest.ContentType = "application/json";
httpWebRequest.Method = "POST";

using (var streamWriter = new StreamWriter(httpWebRequest.GetRequestStream()))
{
    string json = new JavaScriptSerializer().Serialize(new
                {
                    user = "Foo",
                    password = "Baz"
                });

    streamWriter.Write(json);
}

var httpResponse = (HttpWebResponse)httpWebRequest.GetResponse();
using (var streamReader = new StreamReader(httpResponse.GetResponseStream()))
{
    var result = streamReader.ReadToEnd();
}

Answer 3

该HttpClient类型是比WebClient和更新的实现HttpWebRequest.

您只需使用以下行.

string myJson = "{'Username': 'myusername','Password':'pass'}";
using (var client = new HttpClient())
{
    var response = await client.PostAsync(
        "http://yourUrl", 
         new StringContent(myJson, Encoding.UTF8, "application/json"));
}

当您需要HttpClient多次时,建议仅创建一个实例并重复使用或使用新实例HttpClientFactory.

Answer 4

继Sean的帖子之后,没有必要嵌套using语句.通过usingStreamWriter,它将在块的末尾被刷新和关闭,因此不需要显式调用Flush()和Close()方法:

var request = (HttpWebRequest)WebRequest.Create("http://url");
request.ContentType = "application/json";
request.Method = "POST";

using (var streamWriter = new StreamWriter(request.GetRequestStream()))
{
    string json = new JavaScriptSerializer().Serialize(new
                {
                    user = "Foo",
                    password = "Baz"
                });

    streamWriter.Write(json);
}

var response = (HttpWebResponse)request.GetResponse();
using (var streamReader = new StreamReader(response.GetResponseStream()))
{
        var result = streamReader.ReadToEnd();
}

Answer 5

照顾您正在使用的内容类型:

application/json

资料来源:

RFC4627

其他帖子

Answer 6

如果需要异步调用则使用

var request = HttpWebRequest.Create("http://www.maplegraphservices.com/tokkri/webservices/updateProfile.php?oldEmailID=" + App.currentUser.email) as HttpWebRequest;
            request.Method = "POST";
            request.ContentType = "text/json";
            request.BeginGetRequestStream(new AsyncCallback(GetRequestStreamCallback), request);

private void GetRequestStreamCallback(IAsyncResult asynchronousResult)
    {
        HttpWebRequest request = (HttpWebRequest)asynchronousResult.AsyncState;
        // End the stream request operation

        Stream postStream = request.EndGetRequestStream(asynchronousResult);


        // Create the post data
        string postData = JsonConvert.SerializeObject(edit).ToString();

        byte[] byteArray = Encoding.UTF8.GetBytes(postData);


        postStream.Write(byteArray, 0, byteArray.Length);
        postStream.Close();

        //Start the web request
        request.BeginGetResponse(new AsyncCallback(GetResponceStreamCallback), request);
    }

    void GetResponceStreamCallback(IAsyncResult callbackResult)
    {
        HttpWebRequest request = (HttpWebRequest)callbackResult.AsyncState;
        HttpWebResponse response = (HttpWebResponse)request.EndGetResponse(callbackResult);
        using (StreamReader httpWebStreamReader = new StreamReader(response.GetResponseStream()))
        {
            string result = httpWebStreamReader.ReadToEnd();
            stat.Text = result;
        }

    }

Answer 7

我最近提出了一种更简单的发布JSON的方法,还有从我的应用程序中的模型转换的额外步骤.请注意,您必须为控制器创建模型[JsonObject]以获取值并进行转换.

请求:

 var model = new MyModel(); 

 using (var client = new HttpClient())
 {
     var uri = new Uri("XXXXXXXXX"); 
     var json = new JavaScriptSerializer().Serialize(model);
     var stringContent = new StringContent(json, Encoding.UTF8, "application/json");
     var response = await Client.PutAsync(uri,stringContent).Result;
     ...
     ...
  }

模型:

[JsonObject]
[Serializable]
public class MyModel
{
    public Decimal Value { get; set; }
    public string Project { get; set; }
    public string FilePath { get; set; }
    public string FileName { get; set; }
}

服务器端:

[HttpPut]     
public async Task<HttpResponseMessage> PutApi([FromBody]MyModel model)
{
    ...
    ... 
}

Answer 8

警告！我对这个问题有非常强烈的看法。

.NET 现有的 Web 客户端对开发人员不友好！ WebRequest和WebClient是“如何挫败开发人员”的主要示例。它们冗长而复杂；当您只想在 C# 中执行一个简单的 Post 请求时。HttpClient在某种程度上解决了这些问题，但它仍然不足。最重要的是，微软的文档很糟糕……真的很糟糕；除非你想筛选一页又一页的技术简介。

开源来拯救。有三个优秀的开源免费 NuGet 库作为替代。谢天谢地！这些都得到了很好的支持，记录在案，是的，很容易 - 更正......超级容易 - 使用。

• ServiceStack.Text - 快速、轻便且有弹性。
• RestSharp - 简单的 REST 和 HTTP API 客户端
• Flurl - 流畅、便携、可测试的 HTTP 客户端库

它们之间没有太多关系，但我会给 ServiceStack.Text 一点优势……

• Github star大致相同。
• 未解决的问题 & 重要的是任何问题的关闭速度有多快？ServiceStack 在这里因最快的问题解决和没有未解决的问题而获奖。
• 文档？都有很好的文档；然而，ServiceStack 将其提升到了一个新的水平，并以其文档的“黄金标准”而闻名。

好的 - 那么 ServiceStack.Text 中的 JSON 格式的 Post 请求是什么样的？

var response = "http://example.org/login"
    .PostJsonToUrl(new Login { Username="admin", Password="mypassword" });

那是一行代码。简洁大方！将上述内容与 .NET 的 Http 库进行比较。

Answer 9

未提及此选项:

using (var client = new HttpClient())
{
    client.BaseAddress = new Uri("http://localhost:9000/");
    client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));

    var foo = new User
    {
        user = "Foo",
        password = "Baz"
    }

    await client.PostAsJsonAsync("users/add", foo);
}

Answer 10

实现此目的的一些不同且干净的方法是使用 HttpClient 像这样：

public async Task<HttpResponseMessage> PostResult(string url, ResultObject resultObject)
{
    using (var client = new HttpClient())
    {
        HttpResponseMessage response = new HttpResponseMessage();
        try
        {
            response = await client.PostAsJsonAsync(url, resultObject);
        }
        catch (Exception ex)
        {
            throw ex
        }
        return response;
     }
}