远程服务器返回一个错误：(400)坏请求？

Question

我试图从url获得响应，它必须是JSON，如下所示：

{"request_status"：“失败”，"error_message"：“商人ID不正确”，"error_code"："0"，"unique_order_id"：""}

我在我的winForm中的单击事件处理程序中使用了这段代码(它有5个textbox控件每个处理一个特定的参数，我想在textbox textBoxResponse中接收JSON文件。

private void button1_Click(object sender, EventArgs e)
{
    WebRequest request = WebRequest.Create("http://test5.paymobsolutions.com/api/merchant/pay_order_online/");
    request.Method = WebRequestMethods.Http.Post;
    //request.Headers.Add("REF-1", "me1");
    //request.Headers.Add("REF-2", "me2");
    request.Proxy = null;
    using (var streamWriter = new StreamWriter(request.GetRequestStream()))
    {
        PaymentParamters paras = new PaymentParamters { c_cvv_U = textBoxCVV.Text, c_expiry_mm_U = textBoxExM.Text, c_expiry_yy_U = textBoxExY.Text, c_holder_name_U = textBoxHolderName.Text, c_pan_U = textBoxPAN.Text };

        string json = JsonConvert.SerializeObject(paras);
        streamWriter.Write(json);
        streamWriter.Flush();
        streamWriter.Close();
    }
    var response = request.GetResponse();
    using (var streamReader = new StreamReader(response.GetResponseStream()))
    {
        var result = streamReader.ReadToEnd();
        textBoxResponse.Text = result;
    }
}

但有一个例外情况：

远程服务器返回一个错误：(400)坏请求

这个html工作得很好，我想让我的winForm表现得像这样：

<form method="post" action="http://test5.paymobsolutions.com/api/merchant/pay_order_online/">
    <input type="text" placeholder="pan"            name="c_pan_U" value="" />
    <input type="text" placeholder="holder_name"    name="c_holder_name_U" value ="" />
    <input type="text" placeholder="expiry_mm"      name="c_expiry_mm_U" value="" />
    <input type="text" placeholder="expiry_yy"      name="c_expiry_yy_U" value="" />
    <input type="text" placeholder="cvv"            name="c_cvv_U" value="" />
    <input type="submit" />
</form>

Answer 1

HTML将是POSTing ( application/x-www-form-urlencoded或multipart/form-data )。您的服务调用正在尝试编写application/json。这很可能是你问题的症结所在。

服务会接受JSON (检查它的接受头)吗？如果是这样的话，您需要在请求头中设置它。

或者，将您的代码更改为post x-www-form-urlencoded。See this post for a sample，下面发布了一个片段供您参考。

var request = (HttpWebRequest)WebRequest.Create("http://www.example.com/recepticle.aspx");

var postData = "thing1=hello";
    postData += "&thing2=world";
var data = Encoding.ASCII.GetBytes(postData);

request.Method = "POST";
request.ContentType = "application/x-www-form-urlencoded";
request.ContentLength = data.Length;

using (var stream = request.GetRequestStream())
{
    stream.Write(data, 0, data.Length);
}

var response = (HttpWebResponse)request.GetResponse();

var responseString = new StreamReader(response.GetResponseStream()).ReadToEnd();