这几天在调用第三方的接口遇到了GET请求并且还要带有body参数，并且参数类型还得是Json，在我的记忆力GET都是URL传参，网上找了好多方法都不行。用Postman调用可以请求到数据，但是C#代码怎么弄都不行，用Postman生成得代码也不行。一直Http verb GET does not support body。之后找到了一个博文。分享给大家。可以使用，原为转载自https://www.cnblogs.com/wonder223/p/13853864.html#!comments

 try
{
    ///URL接口地址
    HttpWebRequest request = (HttpWebRequest)WebRequest.Create(URL);
    request.Proxy = null;
    request.KeepAlive = false;
    request.Method = "GET";
    request.ContentType = "application/json; charset=UTF-8";
    request.AutomaticDecompression = DecompressionMethods.GZip;
    string Data = "{\"CorpId\":\"300014\"}";///Json参数

        var type = request.GetType();
        var currentMethod = type.GetProperty("CurrentMethod", BindingFlags.NonPublic | BindingFlags.Instance).GetValue(request);
        var methodType = currentMethod.GetType();
        methodType.GetField("ContentBodyNotAllowed", BindingFlags.NonPublic | BindingFlags.Instance).SetValue(currentMethod, false);
 
        using (var streamWriter = new StreamWriter(request.GetRequestStream()))
        {
            streamWriter.Write(Data);
        }
 
    HttpWebResponse response = (HttpWebResponse)request.GetResponse();
    Stream myResponseStream = response.GetResponseStream();
    StreamReader myStreamReader = new StreamReader(myResponseStream, Encoding.UTF8);
    string retString = myStreamReader.ReadToEnd();
 
    myStreamReader.Close();
    myResponseStream.Close();
 
    if (response != null)
    {
        response.Close();
    }
    if (request != null)
    {
        request.Abort();
    }
 
    return retString;
}
catch (Exception ex)
{
    return ("ERROR:" + ex.Message + ":" + ex.InnerException.Message);
}