如何在C＃中设置HttpWebRequest的内容？

Question

HttpWebRequest具有ContentLength和ContentType属性，但是如何实际设置请求的内容？

Answer 1

The following should get you started

byte[]  buffer = ...request data as bytes
var webReq = (HttpWebRequest) WebRequest.Create("http://127.0.0.1/target");

webReq.Method = "REQUIRED METHOD";
webReq.ContentType = "REQUIRED CONTENT TYPE";
webReq.ContentLength = buffer.Length;

var reqStream = webReq.GetRequestStream();
reqStream.Write(buffer, 0, buffer.Length);
reqStream.Close();

var webResp = (HttpWebResponse) webReq.GetResponse();

Answer 2

.NET 4.5 (or .NET 4.0 by adding the Microsoft.Net.Http package from NuGet) provides a lot of additional flexibility in setting the request content. Here is an example:

private System.IO.Stream Upload(string actionUrl, string paramString, Stream paramFileStream, byte [] paramFileBytes)
{
    HttpContent stringContent = new StringContent(paramString);
    HttpContent fileStreamContent = new StreamContent(paramFileStream);
    HttpContent bytesContent = new ByteArrayContent(paramFileBytes);
    using (var client = new HttpClient())
    using (var formData = new MultipartFormDataContent())
    {
        formData.Add(stringContent, "param1", "param1");
        formData.Add(fileStreamContent, "file1", "file1");
        formData.Add(bytesContent, "file2", "file2");
        var response = client.PostAsync(actionUrl, formData).Result;
        if (!response.IsSuccessStatusCode)
        {
            return null;
        }
        return response.Content.ReadAsStreamAsync().Result;
    }
}

Answer 3

Here's a different option for posting info without messing with Bytes and Streams. I personally find it easier to follow, read, and debug.

// Convert Object to JSON
var requestMessage = JsonConvert.SerializeObject(requestObject);
var content = new StringContent(requestMessage, Encoding.UTF8, "application/json");

// Create the Client
var client = new HttpClient();
client.DefaultRequestHeaders.Add(AuthKey, AuthValue);

// Post the JSON
var responseMessage = client.PostAsync(requestEndPoint, content).Result;
var stringResult = responseMessage.Content.ReadAsStringAsync().Result;

// Convert JSON back to the Object
var responseObject = JsonConvert.DeserializeObject<ResponseObject>(stringResult);

Answer 4

HttpWebRequest's RequestStream is where the action is at - rough code...

//build the request object
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(http://someapi.com/);
//write the input data (aka post) to a byte array
byte[] requestBytes = new ASCIIEncoding().GetBytes(inputData);
//get the request stream to write the post to
Stream requestStream = request.GetRequestStream();
//write the post to the request stream
requestStream.Write(requestBytes, 0, requestBytes.Length);

If you're sending extended chars, use UTF8Encoding, make sure you set the right content-type/charset header too.

Answer 5

HttpWebRequest.GetRequestStream() gets the request Stream. After you have set the headers, use GetRequestStream() and write the content to the stream.

This post explains how to transmit files using HttpWebRequest , which should provide a good example of how to send content.

But, basically the format would be

 var stream = request.GetRequestStream();
 stream.Write( stuff );
 stream.Close();
 var response = request.GetResponse();